Fix issue #2446: rotozoom keeps the colorkey flag.

Co-authored-by: Joras <jorascco@al.insper.edu.br>
Co-authored-by: Antonio <antonioarf@al.insper.edu.br>
Co-authored-by: João <joaopga1@al.insper.edu.br>
Co-authored-by: Caio <caioesr@al.insper.edu.br>
Co-authored-by: Cícero <cicerotcv@al.insper.edu.br>
Co-authored-by: Natália <nataliaqmc@al.insper.edu.br>

src_c/rotozoom.c

@@ -511,6 +511,7 @@ rotozoomSurface(SDL_Surface *src, double angle, double zoom, int smooth)
     int dstwidth, dstheight;
     int is32bit;
     int src_converted;
+    Uint32 colorkey;
 
     /*
      * Sanity check
@@ -556,6 +557,7 @@ rotozoomSurface(SDL_Surface *src, double angle, double zoom, int smooth)
         /*
          * -----------------------
          */
+
         int dstwidthhalf, dstheighthalf;
         double sanglezoom, canglezoom, sanglezoominv, canglezoominv;
 
@@ -583,6 +585,13 @@ rotozoomSurface(SDL_Surface *src, double angle, double zoom, int smooth)
          * Target surface is 32bit with source RGBA/ABGR ordering
          */
         rz_dst = PG_CreateSurface(dstwidth, dstheight, rz_src->format->format);
+        if (SDL_GetColorKey(src, &colorkey) == 0) {
+            if (SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey) != 0 ||
+                SDL_SetSurfaceRLE(rz_dst, SDL_TRUE) != 0) {
+                SDL_FreeSurface(rz_dst);
+                return NULL;
+            }
+        }
 
         /*
          * Lock source surface
@@ -629,6 +638,13 @@ rotozoomSurface(SDL_Surface *src, double angle, double zoom, int smooth)
          * Target surface is 32bit with source RGBA/ABGR ordering
          */
         rz_dst = PG_CreateSurface(dstwidth, dstheight, rz_src->format->format);
+        if (SDL_GetColorKey(src, &colorkey) == 0) {
+            if (SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey) != 0 ||
+                SDL_SetSurfaceRLE(rz_dst, SDL_TRUE) != 0) {
+                SDL_FreeSurface(rz_dst);
+                return NULL;
+            }
+        }
 
         /*
          * Lock source surface

src_c/transform.c

@@ -890,6 +890,9 @@ surf_rotozoom(PyObject *self, PyObject *args, PyObject *kwargs)
 
     Py_BEGIN_ALLOW_THREADS;
     newsurf = rotozoomSurface(surf32, angle, scale, 1);
+    if (newsurf == NULL) {
+        PyErr_SetString(pgExc_SDLError, SDL_GetError());
+    }
     Py_END_ALLOW_THREADS;
 
     if (surf32 == surf)

test/transform_test.py

@@ -1287,6 +1287,17 @@ def test_rotozoom(self):
         self.assertEqual(s1.get_rect(), pygame.Rect(0, 0, 0, 0))
         self.assertEqual(s2.get_rect(), pygame.Rect(0, 0, 0, 0))
 
+    def test_rotozoom_keeps_colorkey(self):
+        image = pygame.Surface((64, 64))
+        image.set_colorkey('black')
+        pygame.draw.circle(image, 'red', (32, 32), 32, width=0)
+
+        no_rot = pygame.transform.rotozoom(image, 0, 1.1)
+        self.assertEqual(image.get_colorkey(), no_rot.get_colorkey())
+
+        with_rot = pygame.transform.rotozoom(image, 5, 1.1)
+        self.assertEqual(image.get_colorkey(), with_rot.get_colorkey())
+
     def test_invert(self):
         surface = pygame.Surface((10, 10), depth=32)