Add methods to make use of GPU local texture data copying bypassing a roundtrip to the CPU and back, add sf::Texture::swap to enable swapping texture contents, fixed sf::Font::cleanup not shrinking its allocated pixel buffer storage when the user loads a new font using the same sf::Font object.

include/SFML/Graphics/Texture.hpp

@@ -276,6 +276,43 @@ public:
     ////////////////////////////////////////////////////////////
     void update(const Uint8* pixels, unsigned int width, unsigned int height, unsigned int x, unsigned int y);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Update a part of this texture from another texture
+    ///
+    /// Although the source texture can be smaller than this texture,
+    /// this function is usually used for updating the whole texture.
+    /// The other overload, which has (x, y) additional arguments,
+    /// is more convenient for updating a sub-area of this texture.
+    ///
+    /// No additional check is performed on the size of the passed
+    /// texture, passing a texture bigger than this texture
+    /// will lead to an undefined behavior.
+    ///
+    /// This function does nothing if either texture was not
+    /// previously created.
+    ///
+    /// \param texture Source texture to copy to this texture
+    ///
+    ////////////////////////////////////////////////////////////
+    void update(const Texture& texture);
+
+    ////////////////////////////////////////////////////////////
+    /// \brief Update a part of this texture from another texture
+    ///
+    /// No additional check is performed on the size of the texture,
+    /// passing an invalid combination of texture size and offset
+    /// will lead to an undefined behavior.
+    ///
+    /// This function does nothing if either texture was not
+    /// previously created.
+    ///
+    /// \param texture Source texture to copy to this texture
+    /// \param x       X offset in this texture where to copy the source texture
+    /// \param y       Y offset in this texture where to copy the source texture
+    ///
+    ////////////////////////////////////////////////////////////
+    void update(const Texture& texture, unsigned int x, unsigned int y);
+
     ////////////////////////////////////////////////////////////
     /// \brief Update the texture from an image
     ///
@@ -480,6 +517,14 @@ public:
     ////////////////////////////////////////////////////////////
     Texture& operator =(const Texture& right);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Swap the contents of this texture with those of another
+    ///
+    /// \param right Instance to swap with
+    ///
+    ////////////////////////////////////////////////////////////
+    void swap(Texture& right);
+
     ////////////////////////////////////////////////////////////
     /// \brief Get the underlying OpenGL handle of the texture.
     ///