Made SDL_ReadSurfacePixel a public function

Fixes libsdl-org#8320

include/SDL3/SDL_surface.h

@@ -932,6 +932,31 @@ extern DECLSPEC int SDLCALL SDL_BlitSurfaceUncheckedScaled(SDL_Surface *src,
                                                            const SDL_Rect *dstrect,
                                                            SDL_ScaleMode scaleMode);
 
+/**
+ * Retrieves a single pixel from a surface.
+ *
+ * This function prioritizes correctness over speed: it is suitable for
+ * unit tests, but is not intended for use in a game engine.
+ *
+ * Like SDL_GetRGBA, this uses the entire 0..255 range when converting
+ * color components from pixel formats with less than 8 bits per RGB
+ * component.
+ *
+ * \param surface the surface to read
+ * \param x the horizontal coordinate, 0 <= x < width
+ * \param y the vertical coordinate, 0 <= y < height
+ * \param r a pointer filled in with the red channel, 0-255, or NULL to ignore this channel
+ * \param g a pointer filled in with the green channel, 0-255, or NULL to ignore this channel
+ * \param b a pointer filled in with the blue channel, 0-255, or NULL to ignore this channel
+ * \param a a pointer filled in with the alpha channel, 0-255, or NULL to ignore this channel
+ * \returns 0 on success or a negative error code on failure; call
+ *          SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.0.0.
+ */
+extern DECLSPEC int SDLCALL SDL_ReadSurfacePixel(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a);
+
+
 /**
  * Set the YUV conversion mode
  *

include/SDL3/SDL_test_compare.h

@@ -44,27 +44,6 @@
 extern "C" {
 #endif
 
-/**
- * Retrieves a single pixel from a surface.
- *
- * This function prioritizes correctness over speed: it is suitable for
- * unit tests, but is not intended for use in a game engine.
- *
- * Like SDL_GetRGBA, this uses the entire 0..255 range when converting
- * color components from pixel formats with less than 8 bits per RGB
- * component.
- *
- * \param surface The surface
- * \param x Horizontal coordinate, 0 <= x < width
- * \param y Vertical coordinate, 0 <= y < height
- * \param r Pointer to location to store red channel, 0-255
- * \param g Pointer to location to store green channel, 0-255
- * \param b Pointer to location to store blue channel, 0-255
- * \param a Pointer to location to store alpha channel, 0-255
- * \returns 0 if the surface is valid and the coordinates are in-bounds
- */
-int SDLTest_ReadSurfacePixel(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a);
-
 /**
  * Compares a surface and with reference image data for equality
  *

src/dynapi/SDL_dynapi.sym

@@ -963,6 +963,7 @@ SDL3_0.0.0 {
     SDL_GetHapticFromInstanceID;
     SDL_GetHapticInstanceID;
     SDL_GetHapticName;
+    SDL_ReadSurfacePixel;
     # extra symbols go here (don't modify this line)
   local: *;
 };

src/dynapi/SDL_dynapi_overrides.h

@@ -988,3 +988,4 @@
 #define SDL_GetHapticFromInstanceID SDL_GetHapticFromInstanceID_REAL
 #define SDL_GetHapticInstanceID SDL_GetHapticInstanceID_REAL
 #define SDL_GetHapticName SDL_GetHapticName_REAL
+#define SDL_ReadSurfacePixel SDL_ReadSurfacePixel_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -1013,3 +1013,4 @@ SDL_DYNAPI_PROC(const char*,SDL_GetHapticInstanceName,(SDL_HapticID a),(a),retur
 SDL_DYNAPI_PROC(SDL_Haptic*,SDL_GetHapticFromInstanceID,(SDL_HapticID a),(a),return)
 SDL_DYNAPI_PROC(SDL_HapticID,SDL_GetHapticInstanceID,(SDL_Haptic *a),(a),return)
 SDL_DYNAPI_PROC(const char*,SDL_GetHapticName,(SDL_Haptic *a),(a),return)
+SDL_DYNAPI_PROC(int,SDL_ReadSurfacePixel,(SDL_Surface *a, int b, int c, Uint8 *d, Uint8 *e, Uint8 *f, Uint8 *g),(a,b,c,d,e,f,g),return)

src/test/SDL_test_compare.c

@@ -28,19 +28,11 @@
 */
 #include <SDL3/SDL_test.h>
 
-#include "../video/SDL_surface_pixel_impl.h"
-
 #define FILENAME_SIZE 128
 
 /* Counter for _CompareSurface calls; used for filename creation when comparisons fail */
 static int _CompareSurfaceCount = 0;
 
-int
-SDLTest_ReadSurfacePixel(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
-{
-    return SDL_ReadSurfacePixel_impl(surface, x, y, r, g, b, a);
-}
-
 static void
 LogErrorFormat(const char *name, const SDL_PixelFormat *format)
 {
@@ -96,14 +88,14 @@ int SDLTest_CompareSurfaces(SDL_Surface *surface, SDL_Surface *referenceSurface,
         for (i = 0; i < surface->w; i++) {
             int temp;
 
-            temp = SDLTest_ReadSurfacePixel(surface, i, j, &R, &G, &B, &A);
+            temp = SDL_ReadSurfacePixel(surface, i, j, &R, &G, &B, &A);
             if (temp != 0) {
                 SDLTest_LogError("Failed to retrieve pixel (%d,%d): %s", i, j, SDL_GetError());
                 ret++;
                 continue;
             }
 
-            temp = SDLTest_ReadSurfacePixel(referenceSurface, i, j, &Rd, &Gd, &Bd, &Ad);
+            temp = SDL_ReadSurfacePixel(referenceSurface, i, j, &Rd, &Gd, &Bd, &Ad);
             if (temp != 0) {
                 SDLTest_LogError("Failed to retrieve reference pixel (%d,%d): %s", i, j, SDL_GetError());
                 ret++;

src/video/SDL_surface.c

@@ -24,7 +24,6 @@
 #include "SDL_video_c.h"
 #include "SDL_blit.h"
 #include "SDL_RLEaccel_c.h"
-#include "SDL_surface_pixel_impl.h"
 #include "SDL_pixels_c.h"
 #include "SDL_yuv_c.h"
 #include "../render/SDL_sysrender.h"
@@ -36,11 +35,6 @@ SDL_COMPILE_TIME_ASSERT(surface_size_assumptions,
 
 SDL_COMPILE_TIME_ASSERT(can_indicate_overflow, SDL_SIZE_MAX > SDL_MAX_SINT32);
 
-int SDL_ReadSurfacePixel(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
-{
-    return SDL_ReadSurfacePixel_impl(surface, x, y, r, g, b, a);
-}
-
 /* Public routines */
 
 /*
@@ -1560,6 +1554,68 @@ int SDL_PremultiplyAlpha(int width, int height,
     return 0;
 }
 
+/* This function Copyright 2023 Collabora Ltd., contributed to SDL under the ZLib license */
+int SDL_ReadSurfacePixel(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
+{
+    Uint32 pixel = 0;
+    size_t bytes_per_pixel;
+    Uint8 unused;
+    Uint8 *p;
+
+    if (!surface || !surface->format || !surface->pixels) {
+        return SDL_InvalidParamError("surface");
+    }
+
+    if (x < 0 || x >= surface->w) {
+        return SDL_InvalidParamError("x");
+    }
+
+    if (y < 0 || y >= surface->h) {
+        return SDL_InvalidParamError("y");
+    }
+
+    if (!r) {
+        r = &unused;
+    }
+
+    if (!g) {
+        g = &unused;
+    }
+
+    if (!b) {
+        b = &unused;
+    }
+
+    if (!a) {
+        a = &unused;
+    }
+
+    bytes_per_pixel = surface->format->BytesPerPixel;
+
+    if (bytes_per_pixel > sizeof(pixel)) {
+        return SDL_InvalidParamError("surface->format->BytesPerPixel");
+    }
+
+    if (SDL_MUSTLOCK(surface)) {
+        SDL_LockSurface(surface);
+    }
+
+    p = (Uint8 *)surface->pixels + y * surface->pitch + x * bytes_per_pixel;
+    /* Fill the appropriate number of least-significant bytes of pixel,
+     * leaving the most-significant bytes set to zero */
+#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+    SDL_memcpy(((Uint8 *) &pixel) + (sizeof(pixel) - bytes_per_pixel), p, bytes_per_pixel);
+#else
+    SDL_memcpy(&pixel, p, bytes_per_pixel);
+#endif
+    SDL_GetRGBA(pixel, surface->format, r, g, b, a);
+
+    if (SDL_MUSTLOCK(surface)) {
+        SDL_UnlockSurface(surface);
+    }
+    return 0;
+}
+
 /*
  * Free a surface created by the above function.
  */

test/testshape.c

@@ -88,7 +88,7 @@ static void SDL_CalculateShapeBitmap(SDL_WindowShapeMode mode, SDL_Surface *shap
         bitmap_scanline = bitmap + y * bytes_per_scanline;
         for (x = 0; x < shape->w; x++) {
             alpha = 0;
-            if (SDLTest_ReadSurfacePixel(shape, x, y, &r, &g, &b, &alpha) != 0) {
+            if (SDL_ReadSurfacePixel(shape, x, y, &r, &g, &b, &alpha) != 0) {
                 continue;
             }