release_notes.xml

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<doc>
   <title>Release notes</title>
   <body>


<release_notes>

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<current>
New Stuff:
   - Added the check_sub_option() method to the command line parser check
     object.
   - Added match_endings to the dir_nav utils.
   - Added a set_current_dir() function.
   - Added the distance_to_rect_edge() routine.
   - Added support for user drawn rectangle overlays and selectable overlays
     to the image_display widget.

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a bug in the image_display widget.  If you switched it between
     images of a different size while any kind of zoom was in effect
     it could cause a segmentation fault.

Other:

</current>

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<old name="17.41" date="Jun 12, 2011">
New Stuff:
   - You can now add tasks to a thread_pool by value, using the new
     add_task_by_value() method.

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a bug which caused multiply defined symbol errors during linking
     if the PNG saving routine was #included.

Other:
   - Optimized the threaded and distributed structural svm solvers for the
     case where there are many data samples and the separation oracle is
     quick to evaluate.

</old>

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<old name="17.40" date="Jun 05, 2011">
New Stuff:
   - Added a function for saving to the PNG image format.
   - Added Austin Appleby's excellent MurmurHash3 hashing code and setup some
     additional convenience functions.  These functions are murmur_hash3() and
     various overloads of hash().

Non-Backwards Compatible Changes:
   - Made get_pixel_intensity() more efficient.  However, the value returned
     is slightly different than it used to be for RGB pixel types.

Bug fixes:
   - Setup proper error handling for libpng in the png_loader.  Now if the PNG
     file is corrupted in the middle it won't just print a message and abort
     the program.
   - Fixed a bug in assign_pixel_intensity() that happened when the target pixel
     was an RGB pixel with an alpha channel.

Other:
   - Added a Frequently Asked Questions page
   - Changed the array2d object so you don't have to say array2d&lt;type&gt;::kernel_1a
     anymore to declare it.  Now you just say array2d&lt;type&gt;.

</old>

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<old name="17.39" date="May 22, 2011">
New Stuff:
   - Added tools for distributing the work involved in solving a structured
     SVM problem over many computers and CPUs.
   - Added the bridge.  It allows a dlib::pipe to be used for networked
     communication.

Non-Backwards Compatible Changes:
   - Removed the DLIB_REVISION macro and replaced it with DLIB_MAJOR_VERSION and
     DLIB_MINOR_VERSION.

Bug fixes:

Other:
   - dlib's version control system has switched from Subversion to Mercurial.

</old>

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<old name="17.38" date="May 7, 2011">
New Stuff:
   - Added the max_sum_submatrix() function to the optimization tools.
   - Upgraded the pyramid_down function object so it can create color pyramids.
     Also, added some functions which define the coordinate transforms between
     different layers in an image pyramid.

Non-Backwards Compatible Changes:
   - Changed the oca_problem interface to the oca optimizer.  Now the
     optimization_status() function reports back the current risk and risk gap
     in addition to the overall objective value and objective gap.
   - Changed the stopping condition for the structured svm to the one suggested
     by the Joachims paper.  Now it stops when the risk gap is below a user
     supplied epsilon.

Bug fixes:

Other:
   - Various usability improvements.
   - Improved the feature vector caching in the structural_svm_problem object.
   - Some objects were setup as multi-implementation objects but only had one
     implementation.  I went through dlib and switched these to single implementation
     objects.  So for example, to use the dlib crc32 module you used to declare an
     object of type "crc32::kernel_1a" but now you can just say "crc32".  Note that
     I did this change in a way that maintains backwards compatibility with previous
     versions.  So crc32::kernel_1a is still allowed but that form is officially
     deprecated.  The modified objects are as follows:
      - base64
      - byte_orderer
      - config_reader
      - crc32
      - pipe
      - rand

</old>

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<old name="17.37" date="Mar 24, 2011">
New Stuff:
   - Added a multiclass support vector machine.
   - Added a tool for solving the optimization problem associated with
     structural support vector machines.
   - Added new functions for dealing with sparse vectors: add_to(),
     subtract_from(), max_index_plus_one(), fix_nonzero_indexing(), a
     more flexible dot(), and I renamed assign_dense_to_sparse() to assign()
     and made it more flexible.

Non-Backwards Compatible Changes:
   - Renamed max_index_value_plus_one() (a function for working with graphs) to
     max_index_plus_one() so that it uses the same name as the essentially
     identical function for working with sparse vectors.
   - I simplified the cross_validate_multiclass_trainer(), cross_validate_trainer(),
     test_binary_decision_function(), and test_multiclass_decision_function()
     routines.  They now always return double matrices regardless of any other
     consideration.  This only breaks previous code if you had been assigning
     the result into a float or long double matrix.
   - Renamed assign_dense_to_sparse() to assign()

Bug fixes:
   - Fixed a bug in load_libsvm_formatted_data().  I had forgotten to clear the
     contents of the labels output vector before adding the loaded label data.
   - Fixed a bug in the kernel_matrix() function.  It didn't compile when used
     with sparse samples which were of type std::vector&lt;std::pair&lt;&gt; &gt;.
     Moreover, some of the trainers have a dependency on kernel_matrix() so this
     fix makes those trainers also work with this kind of sparse sample.

Other:
   - Added a value_type typedef to matrix_exp so it's easier to write templates
     which operate on STL containers and matrix objects.
</old>

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<old name="17.36" date="Mar 2, 2011">
New Stuff:
   - Added an implementation of the Hungarian algorithm for solving the optimal
     assignment problem (in the new max_cost_assignment() routine).

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a problem which prevented the any_function unit test from compiling
     in visual studio 2008.

Other:
   - Changed the oca optimizer so that it warm starts the QP subproblem
     rather than resolving it from scratch during each iteration. This
     improves the speed and stability of the algorithm.
</old>

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<old name="17.35" date="Feb 10, 2011">
New Stuff:
   - Added the rr_trainer.  It is a version of krr_trainer which is optimized
     for use with the linear_kernel.
   - Added the approximate_distance_function() routine.  It is the core optimizer
     behind the reduced2() trainer adapter.
   - Added an any_function which supports the same functionality as std::function
     from the upcoming C++0x standard.  I added this so dlib can be modified to
     easily support lambda functions while still being compilable with compilers
     which don't support the new std::function.
   - Added overloads of all the GUI event handlers so you can use general functions
     as callbacks (via any_function).  This way, if you have a C++0x compiler, you
     can use lambda functions with the event handlers.
   - Added the split() function for splitting up strings.

Non-Backwards Compatible Changes:
   - Improved the distance_function object by turning it into a properly
     encapsulated class rather than just a simple struct.  I also added
     overloaded +, -, *, and / operators for this object so you can do the
     kind of arithmetic you would expect on an object which represents a
     point in a vector space.  This breaks backwards compatibility with
     the previous interface though as the member variables are now private.

Bug fixes:
   - Fixed a compile-time error in the kernel_matrix().
   - Fixed a bug in an assert in the spatially_filter_image() function.
   - Applied a patch from Nils Labugt which fixes a runtime bug in the gui_core
     component.  The bug caused a crash when using X11 and Ubuntu 10.10 in
     certain cases.
   - Updated code so that it compiles with the clang compiler.

Other:
   - Updated the image_display widget so you can zoom in and out using the
     mouse wheel.
</old>

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<old name="17.34" date="Jan 03, 2011">
New Stuff:
   - General Stuff
      - Added the promote template
      - Added the basic_type template
      - Added the assign_image_scaled() function
      - Added the unordered_pair object.
      - Added the symmetric_matrix_cache() function
      - Added two new quadratic program solvers.  The solve_qp2_using_smo
        and solve_qp3_using_smo objects.

   - Machine Learning Stuff
      - Added the svm_c_trainer object.  It implements C-SVM classification and
        allows the user to set different C values for each class.
      - Added the svm_one_class_trainer object.
      - Added the svr_trainer object.  It implements epsilon-insensitive
        support vector regression.
      - Added two new any objects.  The any_decision_function for containing
        decision function style objects and the any_trainer for trainers.
      - Added cross_validate_regression_trainer()
      - Added test_regression_function()
      - Added the probabilistic() function.  It is a trainer adapter that
        simply calls train_probabilistic_decision_function().
      - Added tools for multiclass classification
         - Added one_vs_one_trainer
         - Added one_vs_all_trainer
         - Added cross_validate_multiclass_trainer()
         - Added test_multiclass_decision_function()

Non-Backwards Compatible Changes:
  - invalid_svm_nu_error has been renamed to invalid_nu_error.
  - Changed the pixel_traits so that signed grayscale pixel types are allowed.
    This involved adding a few new fields to pixel_traits.  I also changed the
    get_pixel_intensity() function so that its return value is of the same type
    as the basic pixel type rather than always being unsigned long.
  - Removed the kernel_type typedef from the normalized function since this
    meta-object should be capable of working with non-kernel decision functions.
  - train_probabilistic_decision_function() no longer accepts column vectors of
    samples and labels.  Now it only accepts std::vectors of samples and labels.

Bug fixes:
  - Fixed a bug in the deserialization code for the sparse kernels.  The bug
    prevented code which used the deserialize() routine from compiling.

Other:
  - Changed the image display GUI widgets to use the assign_image_scaled()
    function internally.  Now they will accept just about any image and
    do the right thing.
  - Modified the type_safe_union so that you can call apply_to_contents() on const
    type_safe_unions.
  - Added serialization support for std::pair objects.
  - Made the train_probabilistic_decision_function() more general by making it work
    with any kind of trainer object rather than only ones which produce
    dlib::decision_function objects.  I also made it work with trainers that only
    take std::vectors.
  - Added overloads to the config_reader's methods to allow it to load directly
    from a file name given as a string in addition to taking istream objects.
</old>

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<old name="17.33" date="Dec 05, 2010">
New Stuff:
  - Added the ability to add/subtract scalar values to/from all the elements
    of a matrix using the - and + operators.
  - Added a trust region optimizer.
  - Added Levenberg-Marquardt and LM/quasi-newton hybrid methods for solving
    non-linear least squares problems.
  - Added an any container object.

Non-Backwards Compatible Changes:

Bug fixes:
  - Fixed a compiler warning and also a runtime bug in sort_basis_vectors().
    The bug triggered when all the basis vectors were included in the final
    answer.

Other:
  - Added a bunch of overloads to catch operations on diagonal matrices
    and use more efficient code paths for them.  For example, inv(diagm(d))
    turns into diagm(reciprocal(d)).  Multiplication by a diagonal matrix
    is now also handled efficiently.

</old>

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<old name="17.32" date="Nov 13, 2010">
New Stuff:
  - Added a class for reading JPEG image files.
  - Added scale_rows(), flipud() and fliplr() matrix functions.
  - Added console_progress_indicator.  It is a tool for measuring how long a
    task will take.
  - Added sort_basis_vectors().  It is a function for performing supervised
    basis selection.

Non-Backwards Compatible Changes:
   - Renamed the linearly_independent_subset_finder's dictionary_size() member
     function to size().  This way, linearly_independent_subset_finder objects
     can be used in many templated functions which expect objects which look
     like arrays.

Bug fixes:
  - Changed the assert macros so that they don't use __PRETTY_FUNCTION__
    with gcc 4.4.5 since, on Ubuntu at least, this version of gcc segfaults
    when __PRETTY_FUNCTION__ is used within certain template constructs.
  - Improved the alias detection capability of kernel_matrix() expressions.
    Now statements of the form: sample = kernel_matrix(kern, *, sample) can
    be used since the aliasing of sample will be handled.

Other:
  - Generally tried to make things more usable.
  - Optimized matrix expressions such as mat*diagm(vect)
  - Made the code in chol() more robust to indefinite matrices.

</old>

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<old name="17.31" date="Sep 15, 2010">
New Stuff:
   - Added the running_scalar_covariance object.
   - All the matrix decomposition routines now use LAPACK when DLIB_USE_LAPACK
     is #defined.

Non-Backwards Compatible Changes:
   - Removed the dlib::EOTHER constant since it conflicts with visual
     studio 2010.
   - Changed the svd functions so you can't supply output matrices which use
     both column and row major layouts.  Now all the output matrices need to
     use the same memory layout.
   - Removed the qr_decomposition::get_householder() function.

Bug fixes:
   - Minor fixes so that dlib compiles in Visual Studio 2010

Other:
   - Added an overloaded matrix_assign() that handles symmetric kernel_matrix()
     expressions more efficiently by only evaluating the upper triangular part
     of the matrix.

</old>

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<old name="17.30" date="Jul 28, 2010">
New Stuff:

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a compile-time bug in the matrix related to multiplication by
     subm() expressions when the BLAS bindings were enabled.
   - Fixed a bug in train_probabilistic_decision_function() which could
     cause it to go into an infinite loop when working with very large
     datasets.

Other:

</old>

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<old name="17.29" date="Jul 25, 2010">
New Stuff:
  - Added a reference_wrapper implementation and modified the thread_function
    slightly so it works with it.
  - Added an implementation of kernel ridge regression.
  - Added a simple newton search strategy for optimizing functions.

Non-Backwards Compatible Changes:
  - If you have created your own matrix expressions then its possible this
    new release will cause them to not compile.

Bug fixes:
  - Fixed a bug in scale_columns.  It said it didn't have any destructive aliasing
    when in fact it destructively aliased its second argument.
  - Fixed a bug in the random number generator where setting the seed back to ""
    didn't result in the object going back to it's initial state.

Other:
  - Reorganized the matrix expression code.  It's now much simpler and the
    library includes a new example program which details the steps needed to
    create new matrix expressions.
  - Changed the train_probabilistic_decision_function() routine so that it uses
    a more numerically stable method to perform its maximum likelihood optimization.
  - Added missing get/set epsilon functions to the RVM training objects.
    I also changed the default epsilon from 0.0005 to 0.001.
</old>

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<old name="17.28" date="Jun 14, 2010">
New Stuff:
   - Added the simplify_linear_decision_function() routines.
   - Added the find_approximate_k_nearest_neighbors() function.
   - Added the fill_lisf() function.

Non-Backwards Compatible Changes:
   - Made the sample_pair have a default distance of infinity instead of
     the max floating point value.  I also reworked the graph creation functions
     to make them a little more versatile.  Now you can use infinite distances to
     indicate that certain nodes are not connected at all.
   - Changed the linear_manifold_regularizer to normalize the regularization
     parameter by the sum of edge weights instead of the sum of edges.

Bug fixes:
   - Fixed a bug in the timer_kernel_2 object.  In certain rare cases it would
     stop calling the action function and essentially shut down without being
     told to do so.

Other:
   - Made the reduced() and reduced2() functions more efficient.
   - Many small usability improvements here and there.

</old>

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<old name="17.27" date="May 16, 2010">
New Stuff:
   - Added the svm_c_ekm_trainer.  It is a kernelized version of the fast
     linear trainer svm_c_linear_trainer.
   - Added the linear_manifold_regularizer and some supporting tools.
   - Added the sum_rows(), sum_cols(), join_rows(), join_cols(), reshape(),
     and pointer_to_matrix() functions.
   - Added the randomly_subsample() function.

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed some minor compile time bugs on certain older compilers.

Other:
   - Updated the += and -= matrix operators to be a little more flexible.  Now
     if you try to apply them to a matrix of the wrong size it will automatically
     resize the target matrix and just do a normal assignment.
   - Removed the requirement that you load dng files into an image of the exact
     pixel type that created the file.  Now you can use any pixel type.  I also
     changed the code so that grayscale pixels with more than 16 bits get saved as
     16 bit grayscale images instead of 8 bit images.

</old>

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<old name="17.26" date="Mar 07, 2010">
New Stuff:
   - Added the solve_qp_using_smo() function to solve certain quadratic
     programs.
   - Added the oca object.  It is an implementation of the Optimized Cutting
     Plane Algorithm.
   - Added a linear SVM trainer that uses oca.
   - Added an implementation of the Histogram of Oriented Gradients algorithm
   - Added a simple tool for making image pyramids
   - Added the running_covariance object
   - Added a simple linear (i.e. non-kernelized) kmeans implementation
   - Added support for serializing dlib::int64
   - Added some functions to load and save LIBSVM formatted data files.

Non-Backwards Compatible Changes:
   - Changed the definition of dlib's sparse vector format to require
     unsigned integral keys.  Having this requirement is nice because it
     creates a simple correspondence between dense vector index values and
     sparse vector keys.  The previous sparse vector definition was
     excessively generic.
   - Renamed sparse_vector::dot_product() to sparse_vector::dot() so that
     both dense and sparse vectors have a global function with the same
     name (i.e. dot()).

Bug fixes:
   - Fixed a bug discovered by Mitchell Peabody.  In some instances trying to
     deserialize a std::vector would fail to compile.

Other:
   - Increased the number of template arguments of the type_safe_union from 10
     to 20.  Additionally, I made the get_id() function public and renamed it
     to get_type_id().  I also added a comment explaining the serialization
     format of type_safe_union objects.
   - Moved the optimization algorithms into their own page in the documentation.
   - Added a Suggested Books page to the documentation

</old>

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<old name="17.25" date="Feb 05, 2010">
New Stuff:
   - Added the ability to compute transformation matrices that map between
     the representations used by different empirical_kernel_maps.  Also added
     the ability to compute projection error.
   - Added the random_subset_selector object.
   - Added the compute_mean_squared_distance() function.

Non-Backwards Compatible Changes:
   - Modified the logger's hook implementation so that it uses a special stream
     buffer instead of an std::ostringstream.  This way logging doesn't cause
     memory allocations.  This breaks backwards compatibility with the previous
     hook function API but only slightly.  The new hook functions must take a
     const char* instead of std::string.
   - Added the const_ret_type typedef to the matrix_exp.  It is now required that
     all matrix expressions define this type.  This enables the expressions to
     return elements by constant reference when appropriate rather than always
     returning by value.

Bug fixes:
   - Fixed a bug in the matrix BLAS bindings that caused BLAS to return an invalid
     argument error.  The error occurred when general matrix multiply expressions
     were transposed and didn't result in a square matrix.  E.g. mat = trans(a*b)
     where mat isn't square.
   - Fixed potential compile time bugs in the comparison operators for futures.
   - Added a missing check for division by zero in the SURF feature extractor.
   - Modified the find_min_single_variable() function so that it is more
     robust when working with functions that are made up of a bunch of
     constant value strips.  Previously, these kinds of functions could
     cause the optimization to fail.

Other:
   - Changed the regression test suite so that when it sets the logging level
     it now sets it for all loggers.  Not just ones that start with "test."


</old>

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<old name="17.24" date="Jan 04, 2010">
New Stuff:
   - Added some MATLAB style thresholding relational operators to the matrix.
   - Added the kernel_matrix() functions.
   - Added the empirical_kernel_map object.
   - Added the discriminant_pca object.
   - Added the read_write_mutex object.

Non-Backwards Compatible Changes:
   - Renamed the support_vectors member of the decision_function and
     distance_function classes to basis_vectors.  This name more appropriately
     reflects how these two classes are used within the library.
   - Changed the matrix_exp interface slightly.  This could only impact users
     who created their own custom matrix expressions.  If you don't get a
     compiler error then you don't have to worry about it.

Bug fixes:
   - Fixed a minor error in the LBFGS code.
   - Added a missing check for division by zero to the kcentroid, krls,
     and linearly_independent_subset_finder classes.  If someone added
     the zero vector to them as the first training example a division by zero
     could result.
   - There were a few cases where the code wouldn't compile when using
     matrices of complex numbers.  There was also a runtime bug that triggered
     when a rank 1 update was performed where one of the vectors was conjugated
     and two or more transposes were used in certain positions.  This bug
     caused the wrong output to be computed if the BLAS bindings were used.
     Both of these bugs have been fixed.
   - Fixed a bug in the http server that affected cookies with certain kinds of
     data.  The result was invalid data being sent back to the web browser.

Other:
   - Generally improved the BLAS bindings for the matrix object.

</old>

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<old name="17.23" date="Oct 20, 2009">
New Stuff:
   - Added the pointer_to_column_vector function.
   - Added the BOBYQA algorithm for derivative-free optimization.
   - Added some functions to make it easy to do a line search on a function
     of a single variable when derivatives are not available.

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a bug in the cpp pretty printer.  It wasn't parsing
     exponentiated numbers like 1e100 correctly.

Other:
   - Added a model selection example program using grid search
     and the new BOBYQA algorithm.

</old>

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<old name="17.22" date="Sep 10, 2009">
New Stuff:
   - Added an implementation of the L-BFGS algorithm for unconstrained non-linear
     optimization.

Non-Backwards Compatible Changes:
   - Refactored the optimization code.  It is now much more flexible but
     this resulted in changes to the API.  See the optimization example program
     for a discussion of the new API.

Bug fixes:
   - Fixed a bug in the get_filesystem_roots() roots function that
     prevented it from compiling.

Other:

</old>

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<old name="17.21" date="Aug 30, 2009">
New Stuff:
   - Added the ability to use a kernel cache to the batch_trainer object.
   - svm_pegasos can now be configured to use two different lambda arguments
     for use with unbalanced data.
   - Added the reciprocal_max() and dot() matrix functions.
   - Added the bgr_pixel and cv_image objects so that OpenCV images can
     be easily used with dlib routines.

Non-Backwards Compatible Changes:
   - I changed the batch trainers so that they always call clear() on the
     trainer being used before training begins.
   - Modified the svm_pegasos class so that the user can set independent lambda
     parameters for each class.  This breaks backwards compatibility with
     the previous interface slightly and changes the serialization format
     of this class.
   - Split the vector_normalizer into a normal normalizer and a pca normalizer
     version.
   - The zoomable_region widget now uses exponential rather than linear
     zoom scaling since this is much more pleasing to use.  There is now
     a new requirement on the zoom increment that it must be between 0
     and 1.

Bug fixes:
   - Fixed a bug in the cross_validate_trainer_threaded() function.  It could
     deadlock if more than about 10 folds were requested.
   - Fixed the serialization functions for the normalized_function object.
     They will now work with custom normalizer function objects.
   - Fixed a minor bug in the zoomable_region::set_min_zoom_scale() function.
     It didn't always end up zooming in a smooth sensible manner after this
     function was called.

Other:
   - Made the thread_function object more general.   It can now handle
     arbitrary functions of up to four arguments.

</old>

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<old name="17.20" date="Jul 11, 2009">
New Stuff:
   - Added the reshape_to_column_vector() function.
   - Added a hook to the logger object that lets you set a different kind of
     output logging destination (in addition to the std::ostream supported
     already).
   - Upgraded the scoped_ptr so that it can handle array pointers as well
     as customer deleter functions.
   - Added overloads of the kernel_derivative object for all the kernels
     in dlib.

Non-Backwards Compatible Changes:
   - Reworked the config_reader interface a little to make it easier to use.
     In particular, I removed the enumerator over blocks in favor of a simple
     get_blocks() function that just returns a std::vector of all the blocks.
     I also removed the requires clauses on the block and key accessor functions
     and instead made a request for a non-existent key/block result in a non-fatal
     exception.  This way users can let the config reader perform a more natural
     role in config file validation (by catching this exception and acting
     accordingly).
   - It is now illegal to multiply matrices of size zero together.

Bug fixes:
   - Fixed the gaussian() function used by the SURF code.  It wasn't computing
     a properly weighted Gaussian function.
   - Fixed a few things in various parts of the code to avoid compiler errors
     in certain use-cases.
   - Added a missing rethrow statement.  The xml parser would eat exceptions
     thrown by event handlers rather than letting them propagate out as
     documented in the specification.

Other:

</old>

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<old name="17.19" date="May 25, 2009">
New Stuff:
    - Added an implementation of the SURF algorithm which includes the
      following new objects and functions:  integral_image, hessian_pyramid,
      interest_point, surf_point, compute_dominant_angle(),
      compute_surf_descriptor(), haar_x(), haar_y(), get_interest_points(),
      and get_surf_points().
    - Added the zeros_matrix() and ones_matrix() functions.
    - Added serialization support to the type_safe_union object.
    - Added the grow_rect() and shrink_rect() functions.
    - Added the get_files_in_directory_tree() function.
    - Added the null_trainer_type object.
    - Added the roc_trainer_type object.

Non-Backwards Compatible Changes:
    - Removed some extraneous get_kernel() functions from some of the
      trainer adapter classes since they really aren't needed.

Bug fixes:
    - Changed the socket read/write code so that it can handle a large
      number ( > 2 billion) of bytes in I/O calls.
    - Added a missing type cast to the reciprocal() function to fix a compile
      time error you get when you use it with complex&lt;float&gt; type matrices.
    - Fixed a bug in the assign_border_pixels() and zero_border_pixels() functions.
      Their contracts said there was no upper limit on the size of the border that
      could be assigned/zeroed but the implementations failed to handle the case
      where the border was bigger than the image.

Other:
    - Generally cleaned up the code and documentation here and there.
    - Added in Steven Van Ingelgem's patches to improve the usability of the
      HTTP server object.
    - Updated the load_bmp() function so that it is capable of reading BMP
      files that have been compressed with the RLE compression sometimes
      used for 8bit BMP files.
    - Merged in Miguel Grinberg's patch to add a non-blocking read() function to the
      connection object.
</old>

<!-- *******************************************************************************  -->

<old name="17.18" date="Apr 5, 2009">
New Stuff:
   - Added a set of kernels that can operate on sparse vectors.
   - Added the image_window and image_display objects.
   - Added the rotate_point() function and the point_rotator object.

Non-Backwards Compatible Changes:
   - Added Steven Van Ingelgem's patch to add the body of data posted
     back to the server into the incoming data object given to the
     server_http::on_request() handler.  This removes the content_length
     field and replaces it with a string that contains the body of content
     data.

Bug fixes:
   - Fixed a compile time bug in the offset_kernel.

Other:
   - Added optimized overloads of the kcentroid object for various
     linear kernels.
   - Changed all the tests in the dlib test suite to use a new DLIB_TEST
     macro instead of DLIB_CASSERT since the tests really aren't
     technically assertions

</old>

<!-- *******************************************************************************  -->

<old name="17.17" date="Mar 16, 2009">
New Stuff:
   - Added the strings_equal_ignore_case() functions

Non-Backwards Compatible Changes:
   - Changed the on_request() function in the http server
   - Changed the serialization format of the kcentroid and svm_pegasos
     objects
   - By default, the kcentroid now keeps the most linearly independent
     dictionary vectors rather than the newest

Bug fixes:

Other:
   - Split the algorithms documentation page into three pages, algorithms,
     machine learning, and bayes nets.
   - Merged in Steven Van Ingelgem's patch to cleanup the HTTP server and
     add new functionality.  This breaks backwards compatibility with the
     previous on_request() interface but it is easy to update old code and
     it is now much cleaner and easier to use.
   - Changed the kcentroid so that you can tell it to keep the most linearly
     independent vectors rather than the newest vectors.  I then changed the
     svm_pegasos object so that it has a max number of support vector setting
     so that the user can supply an upper limit on the number of support
     vectors to use.

</old>

<!-- *******************************************************************************  -->

<old name="17.16" date="Mar 08, 2009">
New Stuff:
   - Matrix related
      - Added the find_min_and_max(), index_of_min(), index_of_max(), trace(),
        randm(), linspace(), logspace(), and cartesian_product() functions.
   - Machine learning related
      - Added the offset_kernel
      - Added some functions to the kcentroid to allow the user to compute
        the inner_product of kcentroids as well as a few other useful things.
      - Added a kernelized version of the Pegasos SVM training algorithm.

Non-Backwards Compatible Changes:
   - Changed the range() function so that it returns row vectors
     instead of column vectors.

Bug fixes:
   - Changed threading code to avoid a potential race condition during
     program termination.
   - Fixed a few incorrect DLIB_ASSERT statements
   - Fixed a bug in the way Content-type was handled in HTTP posts.
   - Fixed a bug in subm() that showed up when statically dimensioned row
     vectors were used to select a sub matrix.

Other:
   - Added some functions to the rectangle to make it easy
     to get the corner points.
   - The cross validation functions no longer allow invalid_svm_nu_error
     exceptions to escape.  Instead, they are assigned low CV scores.
   - Made std_vector_c able to copy directly from std::vector objects.
   - Added a get_socket_descriptor() function to the connection class.

</old>

<!-- *******************************************************************************  -->

<old name="17.15" date="Feb 03, 2009">
New Stuff:
   - Matrix related
      - Added QR, LU, Cholesky, and eigenvalue decomposition class objects
      - Added overloads for rowm() and colm() that allow you to pick out
        less than an entire vector
      - Added the lowerm() and upperm() functions
      - Added the const_temp_matrix class

Non-Backwards Compatible Changes:
   - Renamed the cholesky_decomposition() function to chol()

Bug fixes:
   - Fixed some errors in the requirements for calling the new rowm() and
     colm() functions.
   - Fixed dlib::abs() so that it returns the right type when used
     with complex matrices.
   - Fixed a race condition in the logger object.  It was missing a needed call
     to unregister_thread_end_handler().  What could happen in some scenarios is,
     during program termination, a global part of the logger object could be destructed
     when it still had outstanding thread end handlers registered to it.

Other:
   - Added an example program that shows how to use the optimization
     functions.
   - Gave the matrix object the ability to factor expressions containing
     trans() function calls into more efficient forms.
   - Generally cleaned up the matrix code
</old>

<!-- *******************************************************************************  -->

<old name="17.14" date="Jan 18, 2009">
New Stuff:
   - Added the multi-line text_box GUI widget.
   - Added the type_safe_union object

Non-Backwards Compatible Changes:
   - Renamed the array::expand() function to array::resize() since it does
     basically the same thing as std::vector::resize() and more than one
     user has told me they found the name "expand" to be confusing.

Bug fixes:

Other:
   - Added an example showing how to use the type_safe_union and pipe
     together.
   - Added a page to the documentation that discusses the dlib coding
     standards and how to contribute to the project.
</old>

<!-- *******************************************************************************  -->

<old name="17.13" date="Jan 05, 2009">
New Stuff:
   - Added the bound_function_pointer object.
   - Added support for futures to the thread_pool object.
   - Added a set of objects that makes it possible to create simulations
     of quantum computing algorithms.
   - Added copy and paste support to the text_field.
   - matrix object stuff
      - Added the range() function as well as overloads of all the various
        sub-matrix selection functions so that you can pick out slices of
        matrices like in Matlab.
      - Added a new template argument to the matrix object that allows the
        user to select the memory layout.  Also added a row_major_layout
        and column_major_layout.
      - The matrix object can now be initialized using a comma separated
        list of values.

Non-Backwards Compatible Changes:
   - Changed the fatal_error exception class so that it aborts your program
     and prints a message if you try to construct it more than once since
     doing so indicates that you ignored the first fatal error.
   - The way matrix expressions work in the library has been changed
     since the last release.  So if you created custom matrix expressions
     then they will need to be updated to use the new matrix expression stuff.

Bug fixes:
   - Fixed a minor bug in how the zoomable_region widget drew itself after
     a resize in some cases.
   - Fixed a problem with draw_line where it didn't always redraw the line
     properly.

Other:
   - A lot of the matrix code has been refactored and optimized.  The matrix
     object will now introduce temporary objects when doing so results in
     better performance.  I also added a simple system for binding
     arbitrary matrix expressions to optimized BLAS routines.
   - Cleaned up the vector and point classes.  Now there is only one class,
     the vector class, and it is capable of representing everything the old
     vector and point class could.  I also added code to make sure the
     vector class does the appropriate type promotions when vector objects
     with different types are used together.
   - Made the vector class inherit from matrix
</old>

<!-- *******************************************************************************  -->

<old name="17.12" date="Nov 10, 2008">
New Stuff:
   - Added user settable styles to most of the gui widgets
   - Added the diagm(), svd2() and svd3() matrix functions
   - Added the thread_pool object

Non-Backwards Compatible Changes:
   - Removed the arrow_button widget and moved its functionality into the
     button widget.
   - Renamed the dragable class to draggable
   - Removed the confusing and unnecessary hidden bool argument to the
     gui widget style drawing functions.
   - Changed some of the events that are about the mouse leaving a widget so
     that they still trigger even if the widget has been disabled or hidden.

Bug fixes:
   - Added some missing mutex locks to the scroll_bar widget
   - Fixed a bug in the fill_gradient_rounded() function. It didn't always
     draw the entire rectangle.
   - Fixed a compile time bug in the pinv() function.  It didn't compile
     when used on statically sized matrices when they weren't square.

Other:
   - The member_function_pointer object now never calls new or delete.
     So it is safe to use in a real time environment.

</old>

<!-- *******************************************************************************  -->

<old name="17.11" date="Oct 20, 2008">
New Stuff:
   - Added the sort_columns() and rsort_columns() functions
   - Added the vector_normalizer object
   - Added the normalized_function object.
   - Added a tensor_product() function for the matrix object.

Non-Backwards Compatible Changes:

Bug fixes:
   - Made it so that the gui event handler thread isn't created at all
     unless some part of an application calls some of the gui_core code.
     In the previous release the event handler thread was executed
     briefly during program termination and could cause problems if no
     windowing environment was available.
   - Fixed an #include statement in the matrix utilities so that it works
     even if you don't specify an include path argument to your compiler.

Other:

</old>

<!-- *******************************************************************************  -->

<old name="17.10" date="Oct 09, 2008">
New Stuff:
   - Added a thread safe shared pointer object
   - Added the popup_menu_region widget.

Non-Backwards Compatible Changes:
   - The on_wheel_up() and on_wheel_down() gui events now take an unsigned long
     argument.
   - Removed the register_program_ending_handler() function from the threading
     API and also changed the dlib thread pool so that it no longer causes
     a terminating program to wait for any outstanding threads to finish
     before allowing the application to end.
   - Changed the serialization format of the linearly_independent_subset_finder
     class.
   - Changed all the font pointers in the gui API's interfaces
     to shared_ptr_thread_safe objects.

Bug fixes:
   - Made the kkmeans class actually use the min_change parameter.
   - Fixed a bug in the linearly_independent_subset_finder object.  Also
     added a way to set a minimum tolerance.
   - Fixed a bug in the scrollable_region widget that caused it to scroll in an
     unpleasant way when the horizontal and vertical scroll increments weren't
     set to the same value.
   - Made one of the arguments to font::draw_string() not be a reference because
     some versions of gcc don't end up doing the right thing when -O3 is
     supplied.
   - Fixed a bug in the covariance() function that prevented it from compiling
     sometimes.

Other:
   - Changed the gui core code around so that it should be safe to make window
     objects at the global scope.
   - Added more control over how the scrollable_region scrolls its region.
     You can now adjust how much it scrolls when the mouse wheel is scrolled
     as well as enabling scrolling via a mouse drag.
   - Modified the library so that it compiles with the Intel compiler.
   - Added some example programs that use the relevance vector machine

</old>

<!-- *******************************************************************************  -->

<old name="17.9" date="Sep 06, 2008">
New Stuff:

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a bug in the tooltip widget
   - Fixed the cmake option to toggle the ENABLE_ASSERTS macro
   - Fixed some bugs in the rvm
   - Fixed the serialization code for the kkmeans object so that it actually
     works
   - Fixed a bug that can trigger when the thread_specific_data object is
     destructed
   - Fixed a bug in the directory navigation gui.  If you tried to go
     into a drive on windows that wasn't mounted you got an error.
     This is now fixed.

Other:
   - Made the dir_nav stuff work with std::vector and dlib::std_vector_c
     as well as dlib::queue objects.
   - Generally cleaned up a bunch of things

</old>

<!-- *******************************************************************************  -->

<old name="17.8" date="Aug 14, 2008">
New Stuff:
   - Added relevance vector machine regression and classification support.
   - Added the cross_validate_trainer_threaded() function
   - Added the length and length_squared matrix functions.

Non-Backwards Compatible Changes:

Bug fixes:
   - Changed gui code a little so that windows don't popup in funny
     places when used with the cygwin X windows system.

Other:
   - Made it easier to use the scoped_ptr with the TCP connection object
   - Optimized the matrix object a little

</old>

<!-- *******************************************************************************  -->

<old name="17.7" date="Jul 25, 2008">
New Stuff:
   - Machine Learning
      - Added the ability to compare kcentroid objects to each other
      - Added the rank_features() function
      - Added the distance_function object
      - Added the reduced_decision_function_trainer object and
        reduced() function
      - Added the reduced_decision_function_trainer2 object and
        reduced2() function
      - Added a radial basis function network trainer
      - Added the linearly_independent_subset_finder object
      - Added the sigmoid_kernel
   - Matrix Utilities
      - Added the inv_upper_triangular() and inv_upper_triangular()
        functions.

Non-Backwards Compatible Changes:
   - Refactored a bunch of the kernel learning code into a much cleaner form.
     But this does change the interface to all the training functions.

Bug fixes:
   - Fixed a bug in the min and max calculation in the running_stats object
   - Removed a bug in the sum() and variance() functions that
     caused them to seg fault when they were used on certain
     matrix of matrix objects.
   - Added a missing check for division by zero to the conjugate gradient
     optimization functions.
   - Added some missing member variables to the .swap and serialization
     functions for the kcentroid object.  So now they should work right.

Other:
   - Added an option to the cmake file to toggle the DLIB_ASSERT macro
   - Added an option to the cmake file to toggle the dlib stack trace macros
   - Made the library compile in Cygwin

</old>

<!-- *******************************************************************************  -->

<old name="17.6" date="Jun 22, 2008">
New Stuff:
   - Merged in Keita Mochizuki's unicode patches to the GUI components.  So
     the dlib GUI now has better unicode support.
   - Added the remove_row and remove_col matrix functions.  Also made all
     three of the above functions capable of taking arguments at run time
     as well as compile time.
   - Added the ability to cap the number of dictionary vectors used by the krls
     and kcentroid object at a user specified number.
   - Added the pick_initial_centers() function
   - Added the running_stats object

Non-Backwards Compatible Changes:
   - Changed the interface to the krls and kcentroid objects somewhat.
   - All of the style objects in the GUI part of the library now use
     dlib::ustring instead of std::string.  This only matters to you if
     you have made your own style objects.
   - Changed the serialization format of the krls, kcentroid, and
     directed_graph_drawer objects.  Note that is also means that the
     files saved by previous versions of the bayes_net_gui_ex program
     won't load with the current version.

Bug fixes:
   - Fixed an aliasing bug in the set_subm(), set_rowm(), and set_colm()
     functions.  It was possible that you could get incorrect results
     if you used these functions to copy one part of a matrix to another
     part of the same matrix if the two areas overlapped.
   - Fixed a minor numerical error in the krls code so now it gets slightly
     better results.

Other:
   - Made the types generated by the matrix operations a lot shorter.  This
     avoids some compiler warnings from visual studio and even some potential
     internal compiler errors in some instances.

</old>

<!-- *******************************************************************************  -->

<old name="17.5" date="Jun 2, 2008">
New Stuff:
   - Added some macros that allow dlib to create a stack trace
   - Added the wrap_function and is_function templates.
   - Added two new events to the text_field object.  One for detecting when the
     user hits enter and another for detecting when input focus is lost.
   - Machine Learning
      - Added a kernel based centroid estimator/novelty detector
      - Added a kernel based k-means clustering algorithm
   - Numerical
      - Added an identity_matrix() function that can take a runtime defined size.
      - Added a bunch of unconstrained optimization stuff to the library.
        It now has a conjugate gradient optimization algorithm as well as
        a quasi-newton algorithm.
      - Added the set_subm, set_rowm, and set_colm functions.

Non-Backwards Compatible Changes:
   - In the krls object:  Added a requires clause to the set_tolerance() member
     function and renamed clear() to clear_dictionary().

Bug fixes:
   - Fixed a bug in the requires clause of the subm() function.  It was
     more restrictive than it should have been.

Other:
   - Added example programs for the krls object as well as the new
     kcentroid and kkmeans objects.

</old>

<!-- *******************************************************************************  -->

<old name="17.4" date="May 12, 2008">
New Stuff:
   - Added an implementation of the kernel recursive least squares algorithm

Non-Backwards Compatible Changes:
   - Broke backwards compatibility in the directed_graph_drawer's serialization
     format when I fixed the bug below.

Bug fixes:
   - Fixed two bugs in the directed_graph_drawer widget.  First, it sometimes
     threw a dlib::fatal_error due to a race condition.  Second, the color of
     the nodes wasn't being serialized when save_graph() was called.
   - Made vector_to_matrix() work for std::vector objects that have non-default
     allocators.

Other:
   - Added some stuff to make people get a really obvious error message
     when they set up the include path incorrectly.

</old>

<!-- *******************************************************************************  -->

<old name="17.3" date="Apr 28, 2008">
New Stuff:
   - Added the vector_to_matrix() function.
   - Added a cholesky_decomposition() function.
   - Added the toggle_button GUI widget
      - Added a default toggle button style as well as check box and
        radio button styles.
   - Added a single click event to list_box
   - Added a save_file_box() and open_existing_file_box() function.

Non-Backwards Compatible Changes:
   - Changed the check_box and radio_button widgets to be specializations of
     the new toggle_button object.  This is a nearly backwards compatible
     change except that the events registered to check_box and radio_button
     clicks must now take the form void event(toggle_button&amp;) or
     void event(void) instead of the previous void event(check_box&amp;) and
     void event(radio_button&amp;).
   - Removed the is_mouse_over bool from the button_style::draw_button()
     function.

Bug fixes:
   - Fixed a compiler error in mingw.
   - Changed the preprocessor checks for the wchar_t overload of
     is_built_in_scalar_type so that it works properly with visual studio.

Other:
   - Added a Bayesian Network GUI that allows you to create a network
     and serialize it to disk.
</old>

<!-- *******************************************************************************  -->

<old name="17.2" date="Apr 21, 2008">
New Stuff:
   - GUI Related
      - Added the scrollable_region widget
      - Added the text_grid widget
      - Added an event to the text_field so you can tell when the
        user modifies it.
      - Added the fit_to_contents() function to the tabbed_display
        widget.
   - Bayesian Network Related
      - Added the node_first_parent_assignment(), node_next_parent_assignment(),
        and node_cpt_filled_out() functions.

Non-Backwards Compatible Changes:
   - Reverted the change in 17.0 where I made drawable::lastx and
     drawable::lasty not match the current location of the mouse inside
     the on_mouse_move() event.  I changed this back to how it was before,
     so now lastx and lasty represent the most current record of where
     the mouse is in *all* events.
   - Changed the functions that control text color in the label and text_field
     widgets to use rgb_pixel objects.  Also added a function to set the
     background color of a text_field.

Bug fixes:
   - Fixed a bug in the bayesian_network_join_tree object that caused it to
     compute incorrect results for some networks.
   - GUI Related
      - Fixed a minor bug in the cursor drawing of the text_field
        gui widget.
      - Fixed a bug in the compute_cursor_rect() function.  It would return an
        incorrectly positioned rectangle for 0 length strings.
      - Changed the way wchar_t is handled in the serialize.h file.  Now
        everything should compile correctly in visual studio regardless of how
        you set the /Zc:wchar_t compiler option.
      - Fixed a bug in the menu_bar widget.  One of the members wasn't being
        initialized when it needed to be.
      - Fixed a bug in the tabbed_display where it didn't redraw itself
        correctly after it was moved by set_pos()

Other:
   - Changed the xml parser so that it counts line numbers
     from the start of the input stream instead of from the
     root tag.
   - Changed the xml parser so that you will only get the fatal_error
     event once if it occurs.
</old>

<!-- *******************************************************************************  -->

<old name="17.1" date="Apr 13, 2008">
New Stuff:
   - Added a zoomable_region widget
   - Added a directed_graph_drawer widget

Non-Backwards Compatible Changes:
   - Changed the first_pixel argument of the draw_string() function
     to be a rectangle like all the other draw functions now use.

Bug fixes:
   - Fixed a bug in the tooltip widget that was triggered when calling
     its member functions without calling set_tooltip_text().  This also
     fixed a bug in the button object that triggered when calling some button
     functions that referenced the tooltip widget.
   - Fixed a problem in the draw_circle and draw_solid_circle functions.
     They didn't draw themselves quite correctly in all cases.

Other:
</old>

<!-- *******************************************************************************  -->

<old name="17.0" date="Apr 07, 2008">
New Stuff:
  - Added a png_loader object
  - GUI related
    - Added a popup_menu widget
    - Added a menu_bar widget
    - Added a tooltip widget
    - Added a user selectable style to the gui button.
    - Added the draw_rounded_rectangle() and fill_gradient_rounded() functions
    - Added the mouse_over_event object to the base_widgets and made the
      button_action inherit from it.
    - Added the drawable::next_free_user_event_number() function
  - matrix and geometry:
    - Added a size() function to matrix_exp and matrix_ref objects.
    - Added a class that represents 2D points
    - Added the following matrix functions:
      - squared(), cubed(), get_rect(), a subm() function that takes
        rectangles, and normalize()
    - Added the following rectangle functions:
      - area(), centered_rect(), translate_rect(), move_rect(), resize_rect(),
        resize_rect_height(), resize_rect_width(), and nearest_point()

Non-Backwards Compatible Changes:
  - Renamed atom() to array_to_matrix()
  - Moved the rectangle object from the gui_core into a new geometry folder
    (only matters if you were directly including the rectangle file)
  - Moved the vector object into the geometry folder.  Also removed the kernel_1a
    stuff.  So there is now only one possible vector implementation.
  - Changed the default position for a rectangle to (0,0) instead of (1,1)
  - Added edge data to the directed_graph.  This breaks backwards compatibility
    with the previous serialization format for directed_graphs.
  - GUI related:
    - Changed the base_window::on_keydown event signature so that it now
      reports more keyboard modifier keys (e.g. alt)
    - Made the functions for drawing on canvas objects take points and pixels
      instead of just a bunch of integers.  Also changed the order of the
      arguments so that the canvas comes first, followed by the location
      to draw on, then what to draw.
    - Moved the canvas drawing functions into the gui_widgets/canvas_drawing.h
      file.
    - Modified the drawable_window so that the drawable::lastx and drawable::lasty
      fields are updated after calls to on_mouse_move.  This way the x and y that
      go into the on_mouse_move actually tell you something.

Bug fixes:
  - Fixed a bug in the floating point serialization code.  It
    didn't handle NaN or infinities correctly.
  - Fixed a bug in the win32 version of the gui_core component.  It was
    possible that calling set_size(), set_pos(), or set_title() could cause
    the program to deadlock.
  - Made the load_bmp() function more robust in the face of weirdly
    written BMP files.
  - Modified the draw_circle() and draw_solid_circle() functions so that they
    only touch each canvas pixel once.  This avoids messing up alpha blending
    if an rgb_alpha_pixel is used.

Other:
  - Removed the old win32 only gui code in the dlib/gui folder.
  - Changed the default GUI font to a nicer Sans Serif font
</old>

<!-- *******************************************************************************  -->

<old name="16.5" date="Mar 04, 2008">
New Stuff:
   - Added another constructor to the thread_function object.
     Now it can take proper function objects as well as normal function
     pointers.
   - Added the probabilistic_decision_function object and svm_nu_train_prob()
     function.

Non-Backwards Compatible Changes:
   - Changed the svm train functions so that the cache_size argument
     now measures the max number of megabytes of memory to use rather
     than number of kernel matrix rows to cache.  It's default
     value is now 200MB.
   - changed the type typedef in the SVM kernel function objects to
     be named sample_type instead of type.

Bug fixes:
   - Fixed a bug in the trim, rtrim, and ltrim functions.  They
     didn't return empty strings when the input string contained all
     trim characters.
   - Fixed a bug in the decision_function's copy constructor

Other:
   - Added an optimization to the working set selection for the svm training code.
     Now the algorithm will prefer to select indices that are in the kernel
     matrix cache when possible.
   - Fixed a problem with the chm documentation file where many of the links
     didn't work.
   - Made the support vector functions capable of operating with floats, doubles,
     and long doubles instead of just the double type.
</old>

<!-- *******************************************************************************  -->

<old name="16.4" date="Feb 22, 2008">
New Stuff:
   - Added aversion of the draw_line() function for images.
   - Added the atom(), rowm(), colm(), and subm() matrix functions.
   - Added some push/pop_back() functions to the array object that are similar
     to the ones in the std::vector.
   - Added the std_vector_c class that wraps std::vector and checks its
     function's preconditions.
   - Added the polynomial_kernel object for use with the svm algorithm.

Non-Backwards Compatible Changes:
   - Changed the svm_nu_cross_validate() function to return a vector
     of both the +1 and -1 cross validation accuracies.

Bug fixes:
   - Fixed a bug in the list_box that caused it to not hide itself properly
     when told to do so.
   - Fixed canvas::fill() gui function so that it should work right
     on 64 bit platforms.

Other:
</old>

<!-- *******************************************************************************  -->

<old name="16.3" date="Feb 12, 2008">
New Stuff:
   - Added memory manager support to the matrix object.

Non-Backwards Compatible Changes:
   - Made the assign_pixel() function saturate grayscale values bigger
     than the target pixel type can handle.  Previously it would just
     truncate the numbers.
   - Removed rand_kernel_1 and rand_kernel_2 because they gave very
     inferior results compared to rand_kernel_3.  I then renamed
     rand_kernel_3 to rand_kernel_1.
   - Renamed rand::get_random_number() to get_random_8bit_number() and also
     added a get_random_16bit_number() and get_random_32bit_number()
   - Added a checksum to compress_stream_kernel_1 and kernel_2.  This
     breaks backwards compatibility with the previous versions.  That is,
     the new implementations will complain that decompression fails if
     you give them data compressed with the old non-checksum version of
     the compression routines.
   - Removed the width() and height() functions from the array2d object.
     Now only the equivalent nc() and nr() member functions remain.
   - Changed array2d::set_size(width,height) to set_size(num_rows, num_cols).
     That is, I switched the order of the two arguments to this function.
     The reason for doing this is to make it have the same form as the
     set_size() member of the matrix object.  This way the usage of the
     set_size() member for these two very similar data structures is
     the same.  Hopefully this will reduce confusion rather than
     make things worse.

Bug fixes:
   - Fixed a bug in the image_widget.  It didn't repaint the screen
     all the way if you gave it a smaller image to display.
   - Fixed a bug in the cat() function that caused the state of the queue
     to be broken if you called cat with an empty queue.
   - Made the queue_sort_1 use a better sorting algorithm.  In particular, it
     will not sort slowly for nearly sorted data.
   - Fixed a bug in the queue_kernel_2 object that caused it to not work
     correctly with the non-default memory managers.

Other:
   - Added example code for the member_function_pointer as well as the matrix
     object.
   - Added some more regression tests and made some of the longer running
     ones execute a lot quicker.
   - Made the unit test suite easier to use.  Now tests just throw an exception
     to indicate an error rather than returning an error code.
   - Added an example program for the multi-layer perceptron neural network.
</old>

<!-- *******************************************************************************  -->
<old name="16.2" date="Jan 25, 2008">
New Stuff:
   - Added the is_signed_type and is_unsigned_type templates
   - Image Processing stuff
      - Added the assign_all_pixels() function
      - Added the assign_border_pixels() function
      - Added the assign_pixel_intensity() function
      - Added the auto_threshold_image() function
      - Added the binary_union() function
      - Added the edge_orientation() function
      - Added the get_histogram() function
      - Added the get_pixel_intensity() function
      - Added the hysteresis_threshold() function
      - Added the sobel_edge_detector() function
      - Added the suppress_non_maximum_edges() function
      - Added the zero_border_pixels() function
      - Changed the pixel_traits structure so that it can support 8, 16, and 32
        bit grayscale pixels.

Non-Backwards Compatible Changes:
   - Added more fields to the pixel_traits template so if you had defined your
     own pixel types you will need to update them.

Bug fixes:
   - Fixed some compiler errors in Visual Studio 2008

Other:
   - Generally tried to clean up the documentation and code in this release

</old>

<!-- *******************************************************************************  -->

<old name="16.1" date="Jan 1, 2008">
New Stuff:
   - Added the randomize_samples() function
   - Added the set_main_font() and main_font() functions to the drawable object.
     So now the drawable widgets can use a user provided font.

Non-Backwards Compatible Changes:
   - Made the named_rectangle object a little easier to use.  It now won't
     let you size it so small that it doesn't display its entire name.

Bug fixes:
   - Fixed a bug in the svm_nu_train() function that caused a crash with
     some inputs.
   - Fixed a compile time error that occurred when compiling the bayesian
     network code in Mac OS X.
   - Fixed a bug in the compute_cursor_pos() function where it would
     return the incorrect value.

Other:
   - Added an example showing how to use the svm functions.

</old>

<!-- *******************************************************************************  -->

<old name="16.0" date="Dec 10, 2007">
New Stuff:
   - Added the left_substr() and right_substr() functions
   - Added the zero_extend_cast() function
   - Added the unsigned_type template
   - Added the uint8 typedef
   - Bayesian Network related
      - Added the assignment object
      - Added the bayes_node object
      - Added the joint_probability_table object
      - Added the conditional_probability_table object
      - Added the bayesian_network_gibbs_sampler object
        This object implements an algorithm that performs approximate inference
        in a Bayesian Network.
      - Added the bayesian_network_join_tree object
        This object implements an algorithm that performs exact inference
        in a Bayesian Network.
   - Set related
      - Added the set_intersection_size() function
      - Added the set_union() function
      - Added the set_intersection() function
      - Added the set_difference() function
   - Graph related
      - Added the graph object
      - Added the is_graph template
      - Added the is_directed_graph template
      - Added the create_moral_graph() function
      - Added the triangulate_graph_and_find_cliques() function
      - Added the graph_contains_length_one_cycle() function
      - Added the find_connected_nodes() function
      - Added the graph_is_connected() function
      - Added the is_clique() function
      - Added the is_maximal_clique() function
      - Added the copy_graph_structure() function
      - Added the create_join_tree() function
      - Added the is_join_tree() function
      - Added the edge() function
   - GUI related
      - Added the base_window::get_display_size() function
      - Added message_box_blocking()
      - Added the bdf_font object which is capable of loading BDF font files into
        the font object used by the gui_widgets
   - Better Unicode support
      - Added the basic_utf8_ifstream: An input stream that can read UTF-8 files
      - Added serialization support for wchar_t and std::wstring
      - Added the is_combining_char() function
      - Added the convert_utf8_to_utf32() function
      - Modified most of the string manipulation functions in dlib/string.h
        to work with any kind of character type
      - The gui widgets' font object now works with Unicode text (i.e. wchar_t
        and unichar strings) as well as with normal char data.

Non-Backwards Compatible Changes:
   - The dlib/all_console.cpp and dlib/all_gui.cpp files have been deprecated
     in favor of a new file.  Now to build with dlib you simply add
     dlib/all/source.cpp to your project regardless of what type of project
     you are building.
   - The GUI program entry point, winmain(), has been removed.  You can now use
     the normal main() entry point or some other non-standard entry point
     provided by your compiler.
   - Renamed directed_graph::node::item to directed_graph::node::data

Bug fixes:
   - Fixed some build issues in gcc 4.2 involving some uses of the std_allocator
   - Fixed some build issues in Visual Studio involving the dir_nav component
     and building with NO_MAKEFILE #defined.
   - Moved the #define that disables the old WinSock API into the sockets cpp
     file.  This should avoid conflicts with people who are using the old WinSock
     API.
   - Changed the tuple template slightly to avoid a bug in Visual Studio 7.1
     that caused a compile time error in some instances.

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.12" date="Nov 18, 2007">
New Stuff:
   - Added a destroy() function to the map, set, hash_map, and hash_set objects.
   - Added the tuple object
   - Added an overload of connect() that has a timeout
   - Added rand_kernel_3 as a random number generator that uses the Mersenne Twister
     algorithm.
   - Added the directed_graph object
   - Added the graph_contains_undirected_cycle() and graph_contains_directed_cycle()
     functions.
   - Added the std_allocator object.   It is a STL style allocator that can use
     the dlib memory manager objects.
   - std::string manipulation functions:
      - Added the cast_to_string() function.
      - Added the tolower() function
      - Added the toupper() function
      - Added the ltrim() function
      - Added the rtrim() function
      - Added the trim() function
      - Added the lpad() function
      - Added the rpad() function
      - Added the pad() function

Non-Backwards Compatible Changes:
   - Changed the default logging level from LNONE to LERROR
   - Renamed the ASSERT macro to DLIB_ASSERT and CASSERT to DLIB_CASSERT.
     This rename avoids a conflict with a macro inside MFC.
   - Changed the logger so that settings are inherited when a new logger
     is instantiated rather than just having the new logger use the
     default settings.
   - Removed the logger::clear() function since it no longer really
     makes sense given the above change.
   - Removed the get_main_thread_id() function and replaced it with the
     is_dlib_thread() function.

Bug fixes:
   - Pushed some things into cpp files because doing so avoids build and/or
     runtime errors on some platforms.

Other:
   - Changed the string_cast() function so that it will recognize the words true
     and false as boolean values.  Also improved the error message inside the
     string_cast_error exception object.

</old>

<!-- *******************************************************************************  -->

<old name="15.11" date="Oct 25, 2007">
New Stuff:
   - Added the covariance() function
   - Added the rgb_alpha_pixel pixel type and modified all relevant functions to
     support it.

Non-Backwards Compatible Changes:
  - The GUI changes that are non-backwards compatible:
       - The alpha parameter is now an unsigned char instead of unsigned int
         and its range is now 0 to 255 instead of 0 to 256.
       - The image_widget no longer has any member functions dealing with
         alpha values.  If you want to use alpha blending you just give it an
         image that has an alpha channel.  The same goes for draw_image().
  - There are now more fields in the pixel_traits template.  So if you were
    defining your own pixels before you will need to update your pixel_traits
    specializations.

Bug fixes:
  - Made some functions non-inline and put some things on the stack
    instead of heap.  Doing this avoids some problems with certain
    kinds of builds in visual studio.

Other:
  - Modified the message_box() function so that it is safe to call end_program()
    from within its callback event.

</old>

<!-- *******************************************************************************  -->

<old name="15.10" date="Oct 09, 2007">
New Stuff:
   - Modified the GUI drawing functions to take an alpha argument to allow
     alpha blending.
   - Added the svm_nu_cross_validate() function to perform k-fold
     cross validation using the svm_nu_train() function.
   - Added the boost enable_if templates
   - Added the rand_float extension to the rand object.
   - New matrix features:
      - Added the pinv() function
      - Changed round_zeros() to use the machine epsilon instead of 1e-6 as
        its default epsilon.
      - Modified the matrix object so that you can declare them with
        a static dimension and a dynamic dimension.  E.g. matrix&lt;float,0,10&gt;
        is now legal and declares a matrix with a fixed number of columns(10)
        and a variable number of rows.
      - Added the equal() function to compare two matrices of floating
        point numbers for near equality.
      - Changed the matrix so that operator(long) works for both
        column vectors and now also for row vectors.
      - Added a set_size() and constructor that takes a single long for use in
        sizing row and column vectors.
      - Added the scale_columns() function

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed an error in svm_nu_train() where it would incorrectly
     complain of incorrect nu values for some datasets.
   - Added a missing std:: qualifier at two points in the dlib/vector code that
     could cause a compiler error in some instances.

Other:
   - Added a term index to the documentation.

</old>

<!-- *******************************************************************************  -->

<old name="15.9" date="Sep 25, 2007">
New Stuff:
   - Added a nu support vector classifier training function.
   - Added a multilayer neural network object.
   - Added the "destructive aliasing" checks into the matrix code.  Now temporary
     matrices are only created during assignment if the right hand side aliases
     the left hand side in a destructive way.  This removes many of the previous
     uses of temporary matrices.
   - Made the sum() matrix function be able to sum matrices of matrices
   - New matrix functions:
      - acos(), asin(), atan(), ceil(), cos(), cosh(), exp(), floor(), log(),
        log10(), mean(), norm(), pow(), reciprocal(), round_zeros(), sin(),
        sinh(), sqrt(), tan(), tanh(), variance(), and more overloads of
        uniform_matrix().

Non-Backwards Compatible Changes:

Bug fixes:
   - Added missing nr() and nc() functions to the uniform_matrix() and
     identity_matrix() functions.
   - Forgot to add a destructor for the dynamically sized matrix resulting in a
     memory leak.  This is now fixed.
   - Fixed various potential compile time errors

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.8" date="Sep 11, 2007">
New Stuff:
   - Added a copy of the boost noncopyable base class.
   - added some smart pointers:
      - added shared_ptr
      - added weak_ptr
      - added scoped_ptr

Non-Backwards Compatible Changes:

Bug fixes:

Other:
   - Cleaned up the assert code and removed the need for the dlib/error.ccp file
   - Made the matrix take better advantage of the compile time sized
     dimensions when it can.

</old>

<!-- *******************************************************************************  -->

<old name="15.7" date="Aug 26, 2007">
New Stuff:
   - Made it so that command line options have a default conversion to bool
     and the bool tells you if they are on the command line or not.
   - Added an implicit conversion to a scalar to the matrix object
     when it is of dimension 1x1.
   - Added the thread_function object
   - Added a function to compute the singular value decomposition of a matrix.

Non-Backwards Compatible Changes:
   - Added two new arguments to the on_request() function.  They allow you to
     see what HTTP headers the client sends you and to control which ones
     you send back.

Bug fixes:

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.6" date="Aug 18, 2007">
New Stuff:
  - matrix object additions:
     - Added some functions to convert between matrix and pixel objects.
     - Added the clamp() function that operates on matrix objects.
     - Added the sigmoid function.
     - Made the matrix object capable of being sized at runtime in addition
       to its original compile time static sizing capability.
     - Added 3 and 4 argument versions of pointwise_multiply()
     - Added the +=, -=, *= and /= operators to the matrix object.

Non-Backwards Compatible Changes:

Bug fixes:
  - Fixed the line numbering in the color pretty printer.  Wasn't being
    done correctly.
  - Fixed a bug in the matrix round() function.
  - Fixed some miscellaneous compile time errors
  - Fixed a bug in the matrix removerc() function.
  - Added some missing checks to catch invalid negative index inputs to
    matrix objects.
  - Fixed a bug in the matrix inv() function.  It could sometimes
    segfault if used on certain singular matrices

Other:
  - string_cast() can now convert hex strings to integers
  - You can now say myarray2d.set_size(0,0) and have it do what
    you would naturally expect.
  - Added some #pragma statements that tell visual studio
    to link the right system libraries automatically.
    So now you don't have to add these things in the
    project settings anymore.

</old>

<!-- *******************************************************************************  -->

<old name="15.5" date="Jul 12, 2007">
New Stuff:
  - Added the set_all_logging_levels(), set_all_logging_output_streams()
    functions
  - Added the configure_loggers_from_file() function which allows you to
    easily configure all logger objects using a textual configuration
    file.

Non-Backwards Compatible Changes:

Bug fixes:
   - Added a workaround into the code that avoids a potential compilation
     error on Mac OS X systems.

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.4" date="Jun 30, 2007">
New Stuff:

Non-Backwards Compatible Changes:

Bug fixes:
   - Fixed a bug in the POSIX version of the hostname_to_ip() function. It was
     screwy if you asked for more than the first IP address (the same address
     might be returned more than once).
   - Fixed a bug in the pipe object's timeout functions.  The timeouts weren't
     working correctly.

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.3" date="Jun 25, 2007">
New Stuff:
   - Added the wait_for_num_blocked_dequeues(), enable_enqueue(),
     disable_enqueue(), and is_enqueue_enabled() functions to the pipe object.
   - The pipe object can now be used with a zero length buffer.

Non-Backwards Compatible Changes:
   - There is no longer a pipe::kernel_1a_c typedef since the pipe
     no longer has any requirements to check (due to the change of allowing
     zero length buffer sizes)

Bug fixes:

Other:
   - Made the ASSERT and CASSERT macros call dlib_assert_breakpoint() when they
     fail.  This way you can easily set a breakpoint on them in a debugging
     tool by breaking on calls to this new function.
   - Fixed some typos and unclear parts of the pipe spec.

</old>

<!-- *******************************************************************************  -->

<old name="15.2" date="Jun 11, 2007">
New Stuff:
   - Added a thread safe version of the config_reader object (in the form of an
     extension to the config_reader)
   - Added the wait_until_empty() function to the pipe object.

Non-Backwards Compatible Changes:
   - Removed the connection::close() and listener::close() functions.  They have
     been replaced by destructors.  To upgrade old code all you have to do is
     replace statements of the form "object->close();" with "delete object;".
     Both statements do exactly the same thing.  However, for connection objects,
     you should probably be using the close_gracefully() function instead.

Bug fixes:
   - Removed a potential compile time error in the dng image format handling code.
   - Fixed a bug in the bigint object.  The destructor was using "delete"
     when it should have been using "delete []"
   - Fixed a resource leak in the POSIX version hostname_to_ip()
   - Fixed a significant memory leak in memory_manager_kernel_1
   - Fixed a memory leak that could occur in memory_manager_kernel_2
     and memory_manager_kernel_3 when the constructor for the object
     being constructed threw an exception.
   - Added a missing delete statement to plug a memory leak
     in the md5 computation code.
   - Fixed an uninitialized variable warning from valgrind
     (in lz77_buffer/lz77_buffer_kernel_2.h).  I think this could
     also potentially result in an error when decoding data but I'm not totally
     sure.  But either way it is fixed now.
   - Changed a call to memcpy to memmove in the sockstreambuf_kernel_2
     implementation since the copy could potentially be of overlapped memory.

Other:
   - Changed the connection::read() and connection::write() functions to take
     longs instead of unsigned longs as the buffer sizes.  They also now
     return longs instead of ints.  This should be a backwards compatible change.
   - Started using the valgrind tool to check for memory errors in the project and
     found a few things.  Very nice tool :)

</old>

<!-- *******************************************************************************  -->

<old name="15.1" date="Jun 04, 2007">
New Stuff:
   - Added the multithreaded_object extension to the threads API
   - Added the load_dng() and save_dng() functions which can load and store
     the DNG lossless compressed image format (which I just made up).

Non-Backwards Compatible Changes:
   - Changed the serialization format for bool to use a 1 byte code rather than 2
     bytes.  So this breaks compatibility with the old format.

Bug fixes:
   - The serialization for bool didn't always work right.  This is now fixed.

Other:

</old>

<!-- *******************************************************************************  -->

<old name="15.0" date="May 16, 2007">
New Stuff:
   - New faster version of the bigint object (bigint_kernel_2) that uses
     the Fast Fourier Transform to perform multiplications.
   - The base_window can now be an "undecorated" window.  This new type is suitable
     for making things like popup menus and the like.
   - Added the on_focus_lost() event to the base_window object
   - Added the on_focus_gained() event to the base_window object
   - Added the on_window_moved() event to the base_window object
   - Added the get_pos() function to the base_window object
   - Updated the gui_widgets's drawable interface stuff to support the three
     new event types and the new window type.
   - Added the drawable::draw_rectangle() function
   - Added serialization support for std::complex.
   - Added the assign_image() function

Non-Backwards Compatible Changes:
   - Removed the color arguments from the drawable_window object's constructor and
     added a new boolean argument (if it is an undecorated window or not).  This
     probably won't break any code but if it does you should get a compiler error
     about it.
   - Made it so you must disable the events in the destructor for your
     drawable gui widgets.  Doing so avoids potential race conditions when
     destructing drawable objects.
   - Made it so that you are required to call close_window() in a window object's
     destructor.  This avoids a potential race condition.

Bug fixes:
   - Added a workaround for a bug in MinGW that caused the regression test suite
     to crash when compiled with -O3.
   - Fixed a potential bug in the X Windows version of the gui_core component.
      Added an extra XFlush() to end_program() because without it a
      program can crash when calling end_program() in certain instances.
   - The spec for the pipe object said that objects you enqueue into it
     had an "initial value for their type" after the function completes. This
     is incorrect, they are swapped into the pipe so they have an undefined
     value afterwards.  I fixed the spec for the pipe to say this.
   - Fixed a bug in the font rendering functions in the gui_widgets
     component.  It could cause a segmentation fault sometimes.
   - Fixed some potential deadlocks in the windows version of the gui_core
     component.
   - Fixed a bug in the rsignaler object.  When you called wait() or
     wait_or_timeout() it only unlocked the associated rmutex once (it could be
     locked more than once and thus might cause a deadlock since the thread
     calling wait() wouldn't actually unlock the mutex in this case).
   - Fixed the initialize_array() function in memory_manger_kernel_3 to be
     exception safe.  Previously if an exception occurred while creating
     an array then a resource leak was created.

Other:
   - Changed the package format for the library somewhat.  The examples are now
     located in their own top level folder.  Additionally, the HTML version of the
     documentation also comes in the same archive as the source rather than in a
     separate download.
   - Started using major and minor version numbers rather than just major ones.

</old>

<!-- *******************************************************************************  -->

<old name="14" date="Apr 11, 2007">
New Stuff:
   - Added operator&lt;&lt; and operator&gt;&gt; iostream operators to the vector object.

Non-Backwards Compatible Changes:
   - Changed the xml_parser's document_handler interface:
     made empty element tags (&lt;like_this/&gt;) trigger the end_element() callback
     and removed the is_empty bool from start_element().

Bug fixes:
   - Fixed a potential race condition between the destruction of the thread pool
     and the "program ending handlers" stuff.

Other:
   - Made the xml parser more robust to different types of new line characters.
   - Modified the source slightly so that it works with mingw.

</old>

<!-- *******************************************************************************  -->

<old name="13" date="Mar 01, 2007">
New Stuff:
   - The config_reader is now enumerable.
   - Added the image_widget gui object.
   - Added nr() and nc() to the array2d object.
   - Added the shutdown_connection() function to the iostream extension
     to the server object.
   - Added the timer_kernel_2 implementation which is a version of the timer object
     that is more efficient in its allocation of threads.
   - Added the timeout object.
   - There is now a CMakeLists.txt file located in the dlib folder.  See
     dlib/examples/CMakeLists.txt and dlib/test/CMakeLists.txt for examples
     that use CMake to build projects using this library.
   - Added the register_program_ending_handler() function to the threading API.

Non-Backwards Compatible Changes:
   - Removed the config_reader::get_blocks() function.  Use the
     new enumerable interface for the config_reader instead.
   - The array2d object now uses longs instead of unsigned longs to report
     its dimensions and access its elements.
   - Added a uint64 to the on_connect() callback in the iostream
     extension to the server object.
   - timer::set_delay_time() now throws and timer::start() now may throw
     std::bad_alloc.

Bug fixes:
   - Fixed a bug in end_program().  In X Windows it might not cause the
     program to end right away if it was called from outside the event
     handling thread.
   - Fixed a bug in the implementation of the timeout part of the
     close_gracefully() function.

Other:
   - The library now works on HP-UX
   - The regression test suite now has command line arguments that
     enable tests to send debug messages to a file.

</old>

<!-- *******************************************************************************  -->

<old name="12" date="Feb 07, 2007">
New Stuff:
   - The http server extension now supports the POST HTTP method.
   - The attribute list object in the xml_parser is now enumerable.
   - Added the threaded object extension
   - Added the uintn.h file which defines fixed sized unsigned integral types.

Non-Backwards Compatible Changes:
   - Renamed the on_get() callback in the http extension to the server object to
     on_request()
   - Removed the network byte order functions from the sockets api.  (They are still
     really there though since they come from actual OS header files.  But
     officially they have been replaced by the byte_orderer component).
   - Renamed dlib/uint64.h to dlib/uintn.h

Bug fixes:

Other:
   - The command line parser will now let you declare long named options with -
     characters in them.
   - Made it so you can use the COMPILE_TIME_ASSERT macros anywhere rather than
     just inside functions.

</old>

<!-- *******************************************************************************  -->

<old name="11" date="Dec 27, 2006">
New Stuff:
   - For dlib::matrix
      - Added the tmp() function
      - Added optimized specializations of inv() and det() for 1x1, 2x2, 3x3 and
        4x4 matrices.
      - Added the removerc() function
   - Sockets related
      - Added the connect() function
      - Added the is_ip_address() function.
      - Added the close_gracefully() function
      - Added the iostream extension to the server object.
      - Added the http extension to the server object.

Non-Backwards Compatible Changes:
   - Changed the cpp_tokenizer to not convert characters to their html form.

Bug fixes:
   - Removed some potential compile time errors.  See the change log for details.

Other:
   - Improved the web site
   - Added some more example code
   - Added more colors to cpp_pretty_printer_kernel_1.
</old>

<!-- *******************************************************************************  -->

<old name="10" date="Nov 28, 2006">
New Stuff:
   - std::map is now serializable
   - Added the matrix object and a bunch of supporting code.
   - Added the list_box graphical widget
   - Added the fill_rect_with_vertical_gradient() function to the
     drawable interfaces list of drawing helpers.
   - Added the open_file_box() function which provides a simple file chooser.

Non-Backwards Compatible Changes:

Bug fixes:
   - Made timestamper::get_timestamp() be a const function like it should.  Fixes
     some compile errors.
   - Fixed a bug in the font::draw_string() function.  It didn't redraw
     multi-line strings right.
   - Fixed a bug in the scroll_bar object that would cause a compile
     error if you tried to call its width() function.
   - Fixed a bug in the array_kernel_1 object.  It would cause a segmentation fault
     when used sometimes.

Other:
</old>

<!-- *******************************************************************************  -->

<old name="9" date="Oct 23, 2006">
New Stuff:
   - Added the following image transformation functions:
      - Added the equalize_histogram() function
      - Added the spatially_filter_image() function
      - Added the threshold_image() function
      - Added the binary_dilation() function
      - Added the binary_erosion() function
      - Added the binary_open() function
      - Added the binary_close() function
      - Added the binary_intersection() function
      - Added the binary_difference() function
      - Added the binary_complement() function
   - Added the clear(), load_from() and default constructor back into the
     config_reader.
   - Made the member_function_pointer copyable and also added operator== and !=
     to it.

Non-Backwards Compatible Changes:
   - Made the vector object templated so you can use types other than double with it.
     But now you
     have to specify what type you want to use which is slightly different.
   - The asc_pair_remover and asc_remover abstract classes now take a third template
     argument.  I highly doubt this effects any code outside the library but it is
     possible.

Bug fixes:
   - Fixed a bug in the base_window::set_size() function.  If you specified a size
     of (0,0) it caused your program to error out.  This has now been fixed.
   - Fixed a bug in the scroll_bar widget.
   - Fixed a bug in save_bmp().  For some image sizes it would output a goofy
     looking skewed image.

Other:
   - Switched everything that used to call operator&lt; directly to instead use
     std::less or to take a template argument that provides a compare functor that
     defaults to std::less.
</old>

<!-- *******************************************************************************  -->

<old name="8" date="Oct 03, 2006">
New Stuff:
   - Added the assign_pixel() function
   - Added the hsi pixel type
   - Added the save_bmp() function
   - Added the static_switch template

Non-Backwards Compatible Changes:
   - Changed how the config_reader works.  It now has a more powerful syntax and
     improved interface.  Converting any old code to use the new version should be
     simple since the new file syntax is very nearly backwards compatible with the
     old syntax.  (i.e. You probably won't have to change anything about your
     config files)
   - Renamed the dlib/image_loader.h file to dlib/image_io.h since it now includes
     the image saver stuff.
   - Renamed the pixel struct to rgb_pixel
   - Renamed pixel_traits::color to pixel_traits::rgb
   - Renamed pixel_traits::scalar to pixel_traits::grayscale

Bug fixes:
   - Fixed a bug in the load_bmp() function.  It would load 24bit bmp files
     incorrectly.
   - Changed the logger so that it won't deadlock if you write something similar to
     my_log &lt;&lt; LINFO &lt;&lt; function_that_also_logs();.  Although this is a
     dumb thing to do.  But even so, it shouldn't deadlock.
   - Fixed a potential linking problem with the vector object.

Other:
   - I decided I'm not going to support Borland v5.5.1 anymore.  There are just too
     many bugs in this compiler.  It is very old at this point so I don't see this
     being a big deal.
   - Made the drawable::draw_image() and load_bmp() functions able to handle images
     of any type of pixel.
   - Pulled the imaging, algorithmic and metaprogramming stuff out of the
     miscellaneous section of the web page and gave them all their own sections.
</old>

<!-- *******************************************************************************  -->

<old name="7" date="Sep 18, 2006">
New Stuff:
   - Added a logger header that prints the date and time.
   - Added the LTRACE logging level
   - Added a buffered implementation of sockstreambuf.

Non-Backwards Compatible Changes:
   - Changed the specs to say that sockstreambuf may be buffered.
     sockstreambuf_kernel_1 is still just as it always has been though.  So all old
     code will still work just as it always has.  But all the same, the specs have
     been changed and now allow for an implementation that is not 100% backwards
     compatible.
   - rand_kernel_2 now emits a different string of random numbers.

Bug fixes:
   - Changed the logger object's implementation to not try to register
     a thread end handler for the main program thread anymore.  This was
     technically a bug according to the spec but it actually did end up
     working the way it was supposed to.  But even so, it shouldn't have
     been doing that.
   - Changed binary_search_tree_kernel_1 so that it avoids a bug in the version of
     gcc on SuSE Enterprise Linux 9.
   - Fixed a bug in the rand_kernel_2 implementation.  It wasn't giving good
     random numbers.

Other:
   - Modified the code so that you don't get any warnings when -Wall is used with
     GCC.
</old>

<!-- *******************************************************************************  -->

<old name="6" date="Aug 30, 2006">
New Stuff:
   - Added the ASSERT_ARE_SAME_TYPE macro
   - Added the is_same_type template
   - Added the get_main_thread_id() function to the threading API
   - Added the thread_specific_data extension to the threading API
   - Added the logger object.
   - Added the auto_unlock object to the threading API.

Non-Backwards Compatible Changes:

Bug fixes:

Other:
   - Added an example that is specifically about using threads
   - Added two examples about using the logger object
</old>

<!-- *******************************************************************************  -->

<old name="5" date="Aug 18, 2006">
New Stuff:
   - Added the memory_manager_stateless object and two implementations of it.
   - Added the MACOSX macro to dlib/platform.h
   - Added a templated version of create_new_thread() that allow you to start
     a thread with a member function.
   - Added the register_thread_end_handler() function to the threading kernel API.
   - Added memory_manager_kernel_3

Non-Backwards Compatible Changes:
   - Changed the meaning of the memory_manager_global::get_number_of_allocations()
     function because the previous definition of it didn't really make sense for
     this object.
   - Changed the threading API to wait for all outstanding threads to terminate
     before allowing the program to end.  It used to just let the OS trash those
     threads when main() ended but this isn't a safe or portable thing to do.  I
     used to assume the user would make sure all their threads were done and had
     cleaned up whatever they were doing before main() ended but this is too much
     of a burden on the end user.  So now the library will wait for your threads to
     end.  You still need to have some way of telling them it is time to stop though.

Bug fixes:
   - Fixed a minor bug in dlib/timer/timer_kernel_1.h.  Its implementation was
     slightly off according to the specification of a timer object.

Other:
   - The byte_order object is now capable of flipping entire arrays.
   - Made it so that the ENABLE_ASSERTS macro is defined whenever ASSERT is
     on.
   - Made the array container use the memory managers.

</old>

<!-- *******************************************************************************  -->

<old name="4" date="Jul 18, 2006">
New Stuff:
   - Added functions to explicitly convert to/from little and big endian to the
     byte_order object.
   - Added the allocate_array() and deallocate_array() functions to the
     memory_manager.
   - Created the memory_manager_global object
   - Added the remove_last_in_order(), position_enumerator() and
     remove_current_element() functions to the binary_search_tree object.

Non-Backwards Compatible Changes:
   - I put an #error directive in the old GUI component to notify anyone
     trying to use it that it is deprecated.  I will be removing it from the
     library in a few months.
   - Switched the reference_counter object back to not using the memory_manager.
     I realized it isn't safe for this object to use the memory_manager since
     it could result in memory_managers freeing each other's allocations.
   - I redefined the pixel_traits template.  It is now a lot simpler and more
     convenient.

Bug fixes:
   - Fixed a minor bug in dlib/rand/rand_kernel_2.cpp

Other:
   - Added some more compile time checks to the byte_orderer object.
   - Changed some includes and preprocessor macros around a little so now
     everything but the GUI stuff compiles in mac OS X.
   - Added inclusion guards to all the .cpp files
   - Added the all_gui.cpp and all_console.cpp files.  They
     include all the .cpp files you need to make gui and
     console applications respectively into one file.
   - Made more containers use the memory_manager.

</old>

<!-- *******************************************************************************  -->

<old name="3" date="May 06, 2006">
New Stuff:
   - Added the enqueue_or_timeout() and dequeue_or_timeout() functions
     to the pipe object.
   - Gave the mouse_tracker the ability to display the mouse position
     relative to a user selected point.
   - Added the message_box() function to the gui_widgets component.
   - Gave the label widget the ability to draw newlines in strings.
   - added the close_window() and is_closed() methods to the base_window
     object.
   - Added the rsignaler extension to the threading API.
   - You can now control the thread pool timeout time by setting the
     DLIB_THREAD_POOL_TIMEOUT #define.
   - Added the get_from_clipboard() and put_on_clipboard() functions
     to the gui_core component.
   - Added the stop_and_wait() function to the timer object.
   - Added the trigger_user_event() function and on_user_event() event
     to the base_window object.  This new event is also forwarded
     to drawable interfaces inside the receiving window.
   - Added the wrap_around() function to the named_rectangle widget.
   - Added the top(), left(), right(), bottom(), width() and height()
     functions to the drawable interface.

Non-Backwards Compatible Changes:
   - Made the radio_button and check_box widgets pass references to themselves
     when they call their click handlers.
   - Switched the sync_extension to use the rmutex and rsignaler objects
     rather than the normal non-reentrant ones. ( Chances are that old
     code that used this will still compile fine anyway. )
   - Changed the return type of rand::get_random_number() to be an
     unsigned char.  I also changed both the implementations of
     rand because they weren't very good at all.
   - Changed the functions related to drawing strings in the font class.
   - Changed the drawable's rectangle to default to being empty
     rather than being a single point.  Most code should not notice
     the difference.

Bug fixes:
   - The event handlers in gui_widgets/drawable.h were private.  They
     should be protected.  This is now fixed.
   - Fixed a bug in the way the scroll_bar was drawn when it was
     the HORIZONTAL type.
   - Changed how the thread pool destructs itself when the program
     is ending.  Previously it was possible to get an error on
     NetBSD when the program was ending.  This is now fixed.
   - The functions related to setting the jump size in the scroll_bar
     widget were private.  They are now public.
   - There was a bug in the MS Windows version of the gui_core component
     where the members of the base_window would not work if called from
     within the on_window_close() event.  This has now been fixed.
   - Made the set_pos() function work right for the mouse_tracker widget.
   - Fixed a bug in the base64 object where the string "" could potentially
     be decoded incorrectly.
   - Made the global swap function for crc32_kernel_1 inline.  This fixes a
     potential linker error.
   - Fixed some potential deadlocking that could occur while using the
     gui widgets.

Other:
   - I moved all the regression tests into the dlib/test folder and
     made a nice driver program to run all of them.
   - I have been using the sourceforge compile farms to test the library
     on various platforms.  It now works for Solaris and some of the BSDs
     in addition to Linux and Windows.
</old>


<!-- *******************************************************************************  -->


<old name="2" date="Apr 08, 2006">
New Stuff:
   - Added the array_expand extension to the array object.
   - Added the cmd_line_parser_check extension to the command line parser.
   - Added the pipe object.
   - All applicable container classes now use the memory_manager component for
     their memory allocation.
   - New implementations of the memory_manager object.
   - Added the copy_functor class.

Non-Backwards Compatible Changes:
   - Moved the wrap_string, narrow, and string_cast functions
     to a new file.  You now have to include dlib/string.h to get
     them.  (This makes a bunch of other things work right in gcc 2.95)
   - Renamed the _L macro to _dT
   - Removed the scopy class
   - Simplified the interface to the memory manager.  It is basically the same
     though.
   - Removed the max_size() methods from the hash_table and binary_search_tree
     objects.
   - Removed the T_is_POD template arguments from the hash_table and
     binary_search_tree objects.
   - Simplified the template arguments to all checking components and extensions.
     They now take the class they are to extend or check as their only template
     argument.  This only affects you if you haven't been using the kernel_nx
     typedefs.

Bug fixes:

Other:
   - I changed a few things around and now a majority of the library
     again compiles under gcc 2.95.  But some things don't and I currently
     don't plan on making them work because it involves hackish workarounds
     of 2.95's bugs.
   - Changed the compress_stream_kernel_1 object so that it will detect data
     corruptions better.  This change will prevent it from correctly decompressing
     data that was compressed with a previous version and has an uncompressed size
     greater than about 20,000 bytes.
   - There is a new cpp file you need to compile:  dlib/error.cpp
   - Moved all the regression testing stuff into the dlib/test folder and made
     a nicer test driver to run them.
</old>


<!-- *******************************************************************************  -->

<old name="1" date="Mar 19, 2006">
New Stuff:
    - Created the byte_orderer object.
    - Created the mouse_tracker gui widget.
    - The sliding_buffer object is now enumerable and serializable.
    - Added the get_filesystem_roots() function to the dir_nar component.
    - Added the create_directory() function to the misc_api component.

Non-Backwards Compatible Changes:
    - The ASSERT macro is now only enabled if DEBUG or ENABLE_ASSERTS
      is defined.

Bug fixes:
    - Fixed a minor bug in the cmd_line_parser object.  If you gave
      an option such as --option=arg when option didn't take any
      arguments it could hang your program.
    - Fixed a bug in wait_or_timeout() in the posix version of the threading
      api.  The time to wait for was being calculated incorrectly and could
      result in an excessive number of spurious returns.
    - Fixed a minor bug in the on_keydown() event for windows.
      I had it set such that the shift and ctrl bools would be false
      if they were the actual keys being pressed.  This isn't what the
      specs say should happen but I had a comment in the windows code
      that made it clear that I did it on purpose.  Go figure :)
      This is now fixed.

Other:
    - Improved the cpp_tokenizer object's ability to recognize numerical
      constants.
    - Improved the text_field gui widget.
    - There are now two assert macros.  One called ASSERT
      and another CASSERT.  They both do the same thing but ASSERT
      is only enabled when DEBUG or ENABLE_ASSERTS is defined.
      All the old ASSERT statements were changed to CASSERT statements.
</old>

<!-- *******************************************************************************  -->

<old name="2006-02-23.01">
New Stuff:
    - Added array_kernel_2 which is a simple layer on top of a C array.
    - Added the tabbed_display GUI widget
    - Added the widget_group GUI widget
    - Added the named_rectangle GUI widget
    - Added the pixel_traits template

Non-Backwards Compatible Changes:
    - The default maximum size for an array object is now 0 rather than
      20,000.
Bug fixes:

Other:
    - made the cpp_pretty_printer a little better about how it handles
      C style code.  Also added support for /*!A html_anchor_name !*/
      style comments.
</old>

<!-- *******************************************************************************  -->

<old name="2006-01-31.02">
New Stuff:
    - Created the array2d object.
    - Created the base64 object.
    - Created the pixel struct.
    - Created the load_bmp() function which can load a BMP image file
      into an array2d object of pixels.
    - Created the drawable::draw_image() function

Non-Backwards Compatible Changes:
    - In the drawable interface I made the z order a long rather
      than unsigned long.
    - The cpp_tokenizer object now has a NUMBER token type.
    - removed the get_ prefix from functions in the cmd_line_parser
      and cmd_line_parser_option objects.  Also changed the
      cmd_line_parser_option::operator[] function to a normal member
      function called argument().

Bug fixes:

Other:
    - cpp_pretty_printer now colors numeric literals a shade of yellow.
</old>

<!-- *******************************************************************************  -->

<old name="2006-01-15.03">
New Stuff:
    - Created the member_function_pointer object.
    - Created the button_action object.
    - Created the arrow_button object.
    - Created the check_box object.
    - Created the radio_button object.
    - Created the scroll_bar object.
    - More drawing functions to draw various things
      onto a canvas object.
    - Added enable/disable functions to the
      drawable interface.

Non-Backwards Compatible Changes:
    - The gui widgets are no longer templated at the
      class level.
    - The drawable object's constructor now takes a
      bit set rather than a bunch of bools to tell it
      which events to enable.
    - I changed the names of some of the functions in the
      gui_widgets component so that they all reflected a
      uniform naming style.

Bug fixes:
    - Fixed a minor bug in the cpp_tokenizer.
    - Minor bug in the timer object. See change log for
      details.

Other:
    - Made the timer object a little more robust
</old>


<!-- *******************************************************************************  -->

</release_notes>
   </body>
</doc>