Add ability to lock certain parts of a surface

This avoids conditional jumps based on uninitalised memory, and
should be faster, and should be lighter on memory.

src/Backends/Rendering.h

@@ -22,8 +22,8 @@ Backend_Surface* Backend_CreateSurface(unsigned int width, unsigned int height);
 void Backend_FreeSurface(Backend_Surface *surface);
 BOOL Backend_IsSurfaceLost(Backend_Surface *surface);
 void Backend_RestoreSurface(Backend_Surface *surface);
-unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch);
+unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch, unsigned int width, unsigned int height);
-void Backend_UnlockSurface(Backend_Surface *surface);
+void Backend_UnlockSurface(Backend_Surface *surface, unsigned int width, unsigned int height);
 void Backend_Blit(Backend_Surface *source_surface, const RECT *rect, Backend_Surface *destination_surface, long x, long y, BOOL colour_key);
 void Backend_ColourFill(Backend_Surface *surface, const RECT *rect, unsigned char red, unsigned char green, unsigned char blue);
 BOOL Backend_SupportsSubpixelGlyphs(void);

src/Backends/Rendering/OpenGL3.cpp

@@ -474,17 +474,17 @@ void Backend_RestoreSurface(Backend_Surface *surface)
 	(void)surface;
 }
 
-unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch)
+unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch, unsigned int width, unsigned int height)
 {
 	if (surface == NULL)
 		return NULL;
 
-	surface->pixels = (unsigned char*)malloc(surface->width * surface->height * 3);
+	surface->pixels = (unsigned char*)malloc(width * height * 3);
-	*pitch = surface->width * 3;
+	*pitch = width * 3;
 	return surface->pixels;
 }
 
-void Backend_UnlockSurface(Backend_Surface *surface)
+void Backend_UnlockSurface(Backend_Surface *surface, unsigned int width, unsigned int height)
 {
 	if (surface == NULL)
 		return;
@@ -493,7 +493,7 @@ void Backend_UnlockSurface(Backend_Surface *surface)
 	glGetIntegerv(GL_TEXTURE_BINDING_2D, &previously_bound_texture);
 
 	glBindTexture(GL_TEXTURE_2D, surface->texture_id);
-	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, surface->width, surface->height, GL_RGB, GL_UNSIGNED_BYTE, surface->pixels);
+	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, surface->pixels);
 	free(surface->pixels);
 
 	glBindTexture(GL_TEXTURE_2D, previously_bound_texture);

src/Backends/Rendering/SDLSurface.cpp

@@ -105,7 +105,7 @@ void Backend_RestoreSurface(Backend_Surface *surface)
 	(void)surface;
 }
 
-unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch)
+unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch, unsigned int width, unsigned int height)
 {
 	if (surface == NULL)
 		return NULL;
@@ -114,7 +114,7 @@ unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch
 	return (unsigned char*)surface->sdlsurface->pixels;
 }
 
-void Backend_UnlockSurface(Backend_Surface *surface)
+void Backend_UnlockSurface(Backend_Surface *surface, unsigned int width, unsigned int height)
 {
 	(void)surface;
 }

src/Backends/Rendering/SDLTexture.cpp

@@ -147,32 +147,32 @@ void Backend_RestoreSurface(Backend_Surface *surface)
 	surface->lost = FALSE;
 }
 
-unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch)
+unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch, unsigned int width, unsigned int height)
 {
 	if (surface == NULL)
 		return NULL;
 
-	*pitch = surface->width * 3;
+	*pitch = width * 3;
 
-	surface->pixels = (unsigned char*)calloc(surface->width * surface->height * 3, 1);	// Make sure these are initialized
+	surface->pixels = (unsigned char*)malloc(width * height * 3);
 
 	return surface->pixels;
 }
 
-void Backend_UnlockSurface(Backend_Surface *surface)
+void Backend_UnlockSurface(Backend_Surface *surface, unsigned int width, unsigned int height)
 {
 	if (surface == NULL)
 		return;
 
-	unsigned char *buffer = (unsigned char*)malloc(surface->width * surface->height * 4);
+	unsigned char *buffer = (unsigned char*)malloc(width * height * 4);
-	unsigned char *buffer_pointer = buffer;
 	const unsigned char *src_pixel = surface->pixels;
 
 	// Convert the SDL_Surface's colour-keyed pixels to RGBA32
-	for (unsigned int y = 0; y < surface->height; ++y)
+	for (unsigned int y = 0; y < height; ++y)
 	{
+		unsigned char *buffer_pointer = &buffer[y * width * 4];
 
-		for (unsigned int x = 0; x < surface->width; ++x)
+		for (unsigned int x = 0; x < width; ++x)
 		{
 			*buffer_pointer++ = src_pixel[0];
 			*buffer_pointer++ = src_pixel[1];
@@ -189,7 +189,8 @@ void Backend_UnlockSurface(Backend_Surface *surface)
 
 	free(surface->pixels);
 
-	SDL_UpdateTexture(surface->texture, NULL, buffer, surface->width * 4);
+	SDL_Rect rect = {0, 0, width, height};
+	SDL_UpdateTexture(surface->texture, &rect, buffer, width * 4);
 
 	free(buffer);
 }

src/Backends/Rendering/Software.cpp

@@ -112,8 +112,11 @@ void Backend_RestoreSurface(Backend_Surface *surface)
 	(void)surface;
 }
 
-unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch)
+unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch, unsigned int width, unsigned int height)
 {
+	(void)width;
+	(void)height;
+
 	if (surface == NULL)
 		return NULL;
 
@@ -121,9 +124,11 @@ unsigned char* Backend_LockSurface(Backend_Surface *surface, unsigned int *pitch
 	return surface->pixels;
 }
 
-void Backend_UnlockSurface(Backend_Surface *surface)
+void Backend_UnlockSurface(Backend_Surface *surface, unsigned int width, unsigned int height)
 {
 	(void)surface;
+	(void)width;
+	(void)height;
 }
 
 void Backend_Blit(Backend_Surface *source_surface, const RECT *rect, Backend_Surface *destination_surface, long x, long y, BOOL colour_key)

src/Draw.cpp

@@ -165,7 +165,7 @@ static BOOL ScaleAndUploadSurface(SDL_Surface *surface, SurfaceID surf_no)
 
 	// IF YOU WANT TO ADD HD SPRITES, THIS IS THE CODE YOU SHOULD EDIT
 	unsigned int pitch;
-	unsigned char *pixels = Backend_LockSurface(surf[surf_no], &pitch);
+	unsigned char *pixels = Backend_LockSurface(surf[surf_no], &pitch, converted_surface->w * magnification, converted_surface->h * magnification);
 
 	if (magnification == 1)
 	{
@@ -206,7 +206,7 @@ static BOOL ScaleAndUploadSurface(SDL_Surface *surface, SurfaceID surf_no)
 		}
 	}
 
-	Backend_UnlockSurface(surf[surf_no]);
+	Backend_UnlockSurface(surf[surf_no], converted_surface->w * magnification, converted_surface->h * magnification);
 	SDL_FreeSurface(converted_surface);
 
 	return TRUE;