Fix RLE usage in the transform module (#2535)

* Only add RLE flag when original surf had RLE

Author: MyreMylar

src_c/rotozoom.c

@@ -12,22 +12,6 @@
 */
 
 #include "_pygame.h"
-
-#if !SDL_VERSION_ATLEAST(2, 0, 14)
-SDL_bool
-PG_SurfaceHasRLE(SDL_Surface *surface)
-{
-    if (surface == NULL) {
-        return SDL_FALSE;
-    }
-
-    if (!(surface->map->info.flags & SDL_COPY_RLE_DESIRED)) {
-        return SDL_FALSE;
-    }
-
-    return SDL_TRUE;
-}
-#endif
 #define NO_PYGAME_C_API
 #include "pygame.h"
 
@@ -48,6 +32,23 @@ typedef struct tColorRGBA {
 #define M_PI 3.141592654
 #endif
 
+#if !SDL_VERSION_ATLEAST(2, 0, 14)
+// Remove this when our minimum version is 2.0.14 or larger
+SDL_bool
+PG_SurfaceHasRLE(SDL_Surface *surface)
+{
+    if (surface == NULL) {
+        return SDL_FALSE;
+    }
+
+    if (!(surface->map->info.flags & SDL_COPY_RLE_DESIRED)) {
+        return SDL_FALSE;
+    }
+
+    return SDL_TRUE;
+}
+#endif
+
 /*
 
  32bit Zoomer with optional anti-aliasing by bilinear interpolation.

src_c/transform.c

@@ -179,7 +179,12 @@ newsurf_fromsurf(SDL_Surface *surf, int width, int height)
     }
 
     if (SDL_GetColorKey(surf, &colorkey) == 0) {
-        if (SDL_SetColorKey(newsurf, SDL_TRUE, colorkey) != 0 ||
+        if (SDL_SetColorKey(newsurf, SDL_TRUE, colorkey) != 0) {
+            PyErr_SetString(pgExc_SDLError, SDL_GetError());
+            SDL_FreeSurface(newsurf);
+            return NULL;
+        }
+        if (PG_SurfaceHasRLE(surf) &&
             SDL_SetSurfaceRLE(newsurf, SDL_TRUE) != 0) {
             PyErr_SetString(pgExc_SDLError, SDL_GetError());
             SDL_FreeSurface(newsurf);

test/transform_test.py

@@ -1627,6 +1627,22 @@ def test_flip_alpha(self):
         self.assertEqual(surf.get_at((0, 0)), surf2.get_at((0, 0)))
         self.assertEqual(surf2.get_at((0, 0)), (255, 0, 0, 255))
 
+    def test_unwanted_rle_not_added(self):
+        surf = pygame.Surface((16, 16))
+        surf.fill((255, 0, 0))
+        surf.set_colorkey((0, 0, 0))
+        surf.set_alpha(64)
+
+        #  scale it to the same size (size doesn't matter here)
+        scaled_surf = pygame.transform.scale(surf, (16, 16))
+        pygame.Surface((100, 100)).blit(scaled_surf, (0, 0))
+
+        self.assertEqual(
+            surf.get_flags() & pygame.RLEACCEL,
+            scaled_surf.get_flags() & pygame.RLEACCEL,
+        )
+        self.assertEqual(scaled_surf.get_at((8, 8)), (255, 0, 0, 255))
+
 
 if __name__ == "__main__":
     unittest.main()