Changed the serialization formats for the matrix and array2d objects so that

they are compatible.  This was done in a way that is backwards compatible with
previous versions of dlib.  That is, we can still load data serialized by
previous dlib versions.  However, older versions of dlib can't load the new
serialization format.

dlib/array2d/array2d_kernel.h

@@ -364,8 +364,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             item.reset();
             while (item.move_next())
@@ -389,9 +393,20 @@ namespace dlib
     {
         try
         {
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
 
             item.set_size(nr,nc);
 

dlib/array2d/array2d_kernel_abstract.h

@@ -265,7 +265,9 @@ namespace dlib
         std::ostream& out 
     );   
     /*!
-        provides serialization support 
+        Provides serialization support.  Note that the serialization formats used by the
+        dlib::matrix and dlib::array2d objects are compatible.  That means you can load the
+        serialized data from one into another and it will work properly.
     !*/
 
     template <

dlib/array2d/serialize_pixel_overloads.h

@@ -31,8 +31,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             COMPILE_TIME_ASSERT(sizeof(rgb_pixel) == 3);
             
@@ -57,9 +61,20 @@ namespace dlib
         {
             COMPILE_TIME_ASSERT(sizeof(rgb_pixel) == 3);
 
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
 
             item.set_size(nr,nc);
 
@@ -85,8 +100,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             COMPILE_TIME_ASSERT(sizeof(bgr_pixel) == 3);
 
@@ -111,9 +130,21 @@ namespace dlib
         {
             COMPILE_TIME_ASSERT(sizeof(bgr_pixel) == 3);
 
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
+
 
             item.set_size(nr,nc);
 
@@ -139,8 +170,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             COMPILE_TIME_ASSERT(sizeof(hsi_pixel) == 3);
 
@@ -165,9 +200,21 @@ namespace dlib
         {
             COMPILE_TIME_ASSERT(sizeof(hsi_pixel) == 3);
 
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
+
 
             item.set_size(nr,nc);
 
@@ -193,8 +240,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             COMPILE_TIME_ASSERT(sizeof(rgb_alpha_pixel) == 4);
 
@@ -219,9 +270,21 @@ namespace dlib
         {
             COMPILE_TIME_ASSERT(sizeof(rgb_alpha_pixel) == 4);
 
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
+
 
             item.set_size(nr,nc);
 
@@ -247,8 +310,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nc(),out);
-            serialize(item.nr(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
 
             if (item.size() != 0)
                 out.write((char*)&item[0][0], sizeof(unsigned char)*item.size());
@@ -269,9 +336,20 @@ namespace dlib
     {
         try
         {
-            long nc, nr;
-            deserialize(nc,in);
+            long nr, nc;
             deserialize(nr,in);
+            deserialize(nc,in);
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+            else
+            {
+                std::swap(nr,nc);
+            }
+
 
             item.set_size(nr,nc);
 

dlib/matrix/matrix.h

@@ -1694,8 +1694,12 @@ namespace dlib
     {
         try
         {
-            serialize(item.nr(),out);
-            serialize(item.nc(),out);
+            // The reason the serialization is a little funny is because we are trying to
+            // maintain backwards compatibility with an older serialization format used by
+            // dlib while also encoding things in a way that lets the array2d and matrix
+            // objects have compatible serialization formats.
+            serialize(-item.nr(),out);
+            serialize(-item.nc(),out);
             for (long r = 0; r < item.nr(); ++r)
             {
                 for (long c = 0; c < item.nc(); ++c)
@@ -1728,6 +1732,13 @@ namespace dlib
             deserialize(nr,in); 
             deserialize(nc,in); 
 
+            // this is the newer serialization format
+            if (nr < 0 || nc < 0)
+            {
+                nr *= -1;
+                nc *= -1;
+            }
+
             if (NR != 0 && nr != NR)
                 throw serialization_error("Error while deserializing a dlib::matrix.  Invalid rows");
             if (NC != 0 && nc != NC)

dlib/matrix/matrix_abstract.h

@@ -672,7 +672,9 @@ namespace dlib
         std::ostream& out
     );   
     /*!
-        Provides serialization support 
+        Provides serialization support.  Note that the serialization formats used by the
+        dlib::matrix and dlib::array2d objects are compatible.  That means you can load the
+        serialized data from one into another and it will work properly.
     !*/
 
     template <