Fixed bug 2924 - SDL_CreateRGBSurface[From] versions that take SDL_PIXELFORMAT enum

Daniel Gibson

Currently, SDL_CreateRGBSurface() and SDL_CreateRGBSurfaceFrom() take Uint32 masks for RGBA to "describe" the Pixelformat of the surface.
Internally those value are only used to map to one of the SDL_PIXELFORMAT_* enum values that are used for further processing.

I think it would be both handy and more efficient to be able to specify SDL_PIXELFORMAT_* yourself without using SDL_PixelFormatEnumToMasks() to create masks first, so I implemented functions that do that:
SDL_CreateRGBSurfaceWithFormat() and SDL_CreateRGBSurfaceWithFormatFrom() which are like the versions without "WithFormat" but instead of taking 4 Uint32s for R/G/B/A masks, they take one for a SDL_PIXELFORMAT_* enum value.

Together with https://bugzilla.libsdl.org/show_bug.cgi?id=2923 creating a SDL_Surface* from RGBA data (e.g. from stb_image)  is as easy as
  surf = SDL_SDL_CreateRGBSurfaceWithFormat(0, w, h, bppToUse*8, SDL_PIXELFORMAT_RGBA32);

include/SDL_surface.h

@@ -118,6 +118,8 @@ typedef int (*SDL_blit) (struct SDL_Surface * src, SDL_Rect * srcrect,
 extern DECLSPEC SDL_Surface *SDLCALL SDL_CreateRGBSurface
     (Uint32 flags, int width, int height, int depth,
      Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask);
+extern DECLSPEC SDL_Surface *SDLCALL SDL_CreateRGBSurfaceWithFormat
+    (Uint32 flags, int width, int height, int depth, Uint32 format);
 extern DECLSPEC SDL_Surface *SDLCALL SDL_CreateRGBSurfaceFrom(void *pixels,
                                                               int width,
                                                               int height,
@@ -127,6 +129,8 @@ extern DECLSPEC SDL_Surface *SDLCALL SDL_CreateRGBSurfaceFrom(void *pixels,
                                                               Uint32 Gmask,
                                                               Uint32 Bmask,
                                                               Uint32 Amask);
+extern DECLSPEC SDL_Surface *SDLCALL SDL_CreateRGBSurfaceWithFormatFrom
+    (void *pixels, int width, int height, int depth, int pitch, Uint32 format);
 extern DECLSPEC void SDLCALL SDL_FreeSurface(SDL_Surface * surface);
 
 /**

src/dynapi/SDL_dynapi_overrides.h

@@ -445,6 +445,8 @@
 #define SDL_iconv_close SDL_iconv_close_REAL
 #define SDL_iconv SDL_iconv_REAL
 #define SDL_iconv_string SDL_iconv_string_REAL
+#define SDL_CreateRGBSurfaceWithFormat SDL_CreateRGBSurfaceWithFormat_REAL
+#define SDL_CreateRGBSurfaceWithFormatFrom SDL_CreateRGBSurfaceWithFormatFrom_REAL
 #define SDL_CreateRGBSurface SDL_CreateRGBSurface_REAL
 #define SDL_CreateRGBSurfaceFrom SDL_CreateRGBSurfaceFrom_REAL
 #define SDL_FreeSurface SDL_FreeSurface_REAL
@@ -607,3 +609,5 @@
 #define SDL_RenderGetIntegerScale SDL_RenderGetIntegerScale_REAL
 #define SDL_DequeueAudio SDL_DequeueAudio_REAL
 #define SDL_SetWindowResizable SDL_SetWindowResizable_REAL
+#define SDL_CreateRGBSurfaceWithFormat SDL_CreateRGBSurfaceWithFormat_REAL
+#define SDL_CreateRGBSurfaceWithFormatFrom SDL_CreateRGBSurfaceWithFormatFrom_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -641,3 +641,5 @@ SDL_DYNAPI_PROC(int,SDL_RenderSetIntegerScale,(SDL_Renderer *a, SDL_bool b),(a,b
 SDL_DYNAPI_PROC(SDL_bool,SDL_RenderGetIntegerScale,(SDL_Renderer *a),(a),return)
 SDL_DYNAPI_PROC(Uint32,SDL_DequeueAudio,(SDL_AudioDeviceID a, void *b, Uint32 c),(a,b,c),return)
 SDL_DYNAPI_PROC(void,SDL_SetWindowResizable,(SDL_Window *a, SDL_bool b),(a,b),)
+SDL_DYNAPI_PROC(SDL_Surface*,SDL_CreateRGBSurfaceWithFormat,(Uint32 a, int b, int c, int d, Uint32 e),(a,b,c,d,e),return)
+SDL_DYNAPI_PROC(SDL_Surface*,SDL_CreateRGBSurfaceWithFormatFrom,(void *a, int b, int c, int d, int e, Uint32 f),(a,b,c,d,e,f),return)

src/video/SDL_surface.c

@@ -27,27 +27,20 @@
 #include "SDL_pixels_c.h"
 
 /* Public routines */
+
 /*
- * Create an empty RGB surface of the appropriate depth
+ * Create an empty RGB surface of the appropriate depth using the given
+ * enum SDL_PIXELFORMAT_* format
  */
 SDL_Surface *
-SDL_CreateRGBSurface(Uint32 flags,
-                     int width, int height, int depth,
-                     Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
+SDL_CreateRGBSurfaceWithFormat(Uint32 flags, int width, int height, int depth,
+                               Uint32 format)
 {
     SDL_Surface *surface;
-    Uint32 format;
 
     /* The flags are no longer used, make the compiler happy */
     (void)flags;
 
-    /* Get the pixel format */
-    format = SDL_MasksToPixelFormatEnum(depth, Rmask, Gmask, Bmask, Amask);
-    if (format == SDL_PIXELFORMAT_UNKNOWN) {
-        SDL_SetError("Unknown pixel format");
-        return NULL;
-    }
-
     /* Allocate the surface */
     surface = (SDL_Surface *) SDL_calloc(1, sizeof(*surface));
     if (surface == NULL) {
@@ -105,7 +98,7 @@ SDL_CreateRGBSurface(Uint32 flags,
     }
 
     /* By default surface with an alpha mask are set up for blending */
-    if (Amask) {
+    if (surface->format->Amask) {
         SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_BLEND);
     }
 
@@ -114,6 +107,26 @@ SDL_CreateRGBSurface(Uint32 flags,
     return surface;
 }
 
+/*
+ * Create an empty RGB surface of the appropriate depth
+ */
+SDL_Surface *
+SDL_CreateRGBSurface(Uint32 flags,
+                     int width, int height, int depth,
+                     Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask)
+{
+    Uint32 format;
+
+    /* Get the pixel format */
+    format = SDL_MasksToPixelFormatEnum(depth, Rmask, Gmask, Bmask, Amask);
+    if (format == SDL_PIXELFORMAT_UNKNOWN) {
+        SDL_SetError("Unknown pixel format");
+        return NULL;
+    }
+
+    return SDL_CreateRGBSurfaceWithFormat(flags, width, height, depth, format);
+}
+
 /*
  * Create an RGB surface from an existing memory buffer
  */
@@ -125,8 +138,30 @@ SDL_CreateRGBSurfaceFrom(void *pixels,
 {
     SDL_Surface *surface;
 
-    surface =
-        SDL_CreateRGBSurface(0, 0, 0, depth, Rmask, Gmask, Bmask, Amask);
+    surface = SDL_CreateRGBSurface(0, 0, 0, depth, Rmask, Gmask, Bmask, Amask);
+    if (surface != NULL) {
+        surface->flags |= SDL_PREALLOC;
+        surface->pixels = pixels;
+        surface->w = width;
+        surface->h = height;
+        surface->pitch = pitch;
+        SDL_SetClipRect(surface, NULL);
+    }
+    return surface;
+}
+
+/*
+ * Create an RGB surface from an existing memory buffer using the given given
+ * enum SDL_PIXELFORMAT_* format
+ */
+SDL_Surface *
+SDL_CreateRGBSurfaceWithFormatFrom(void *pixels,
+                         int width, int height, int depth, int pitch,
+                         Uint32 format)
+{
+    SDL_Surface *surface;
+
+    surface = SDL_CreateRGBSurfaceWithFormat(0, 0, 0, depth, format);
     if (surface != NULL) {
         surface->flags |= SDL_PREALLOC;
         surface->pixels = pixels;