Made SDL_ReadSurfacePixel a public function

Fixes https://github.com/libsdl-org/SDL/issues/8320

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.
  */

src/video/SDL_surface_pixel_impl.h

@@ -1,80 +0,0 @@
-/*
-  Copyright 1997-2024 Sam Lantinga <slouken@libsdl.org>
-  Copyright 2023 Collabora Ltd.
-
-  This software is provided 'as-is', without any express or implied
-  warranty.  In no event will the authors be held liable for any damages
-  arising from the use of this software.
-
-  Permission is granted to anyone to use this software for any purpose,
-  including commercial applications, and to alter it and redistribute it
-  freely, subject to the following restrictions:
-
-  1. The origin of this software must not be misrepresented; you must not
-     claim that you wrote the original software. If you use this software
-     in a product, an acknowledgment in the product documentation would be
-     appreciated but is not required.
-  2. Altered source versions must be plainly marked as such, and must not be
-     misrepresented as being the original software.
-  3. This notice may not be removed or altered from any source distribution.
-*/
-
-#include "SDL3/SDL.h"
-
-/* Internal implementation of SDL_ReadSurfacePixel, shared between SDL_shape
- * and SDLTest */
-static int SDL_ReadSurfacePixel_impl(SDL_Surface *surface, int x, int y, Uint8 *r, Uint8 *g, Uint8 *b, Uint8 *a)
-{
-    Uint32 pixel = 0;
-    size_t bytes_per_pixel;
-    void *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) {
-        return SDL_InvalidParamError("r");
-    }
-
-    if (!g) {
-        return SDL_InvalidParamError("g");
-    }
-
-    if (!b) {
-        return SDL_InvalidParamError("b");
-    }
-
-    if (!a) {
-        return SDL_InvalidParamError("a");
-    }
-
-    bytes_per_pixel = surface->format->BytesPerPixel;
-
-    if (bytes_per_pixel > sizeof(pixel)) {
-        return SDL_InvalidParamError("surface->format->BytesPerPixel");
-    }
-
-    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);
-
-    SDL_UnlockSurface(surface);
-    return 0;
-}