Stamp performance improvements

+ Stamps are scaled before they are colorized or tinted,
   to increase performance.
 + The current stamp (in its current form: size, orientation,
   and color) is cached, so it may be applied to the canvas
   many times without having to re-render.
   (No longer scaling and tinting every time you click.)

Closes https://sourceforge.net/p/tuxpaint/bugs/147/
(h/t Andre Anckaert)

docs/CHANGES.txt

@@ -7,7 +7,7 @@ Various contributors (see below, and AUTHORS.txt)
 http://www.tuxpaint.org/
 
 
-2022.January.24 (0.9.28)
+2022.January.25 (0.9.28)
   * Improvements to "Paint" and "Lines" tools:
     ------------------------------------------
     * Brush spacing may now be altered within Tux Paint.
@@ -23,6 +23,18 @@ http://www.tuxpaint.org/
       (h/t Areti Tsolakidou for the suggestion)
       Bill Kendrick <bill@newbreedsoftware.com>
 
+  * Improvements to "Stamp" tool:
+    -----------------------------
+    * Stamp performance improvements
+      + Stamps are scaled before they are colorized or tinted,
+        to increase performance.
+      + The current stamp (in its current form: size, orientation,
+        and color) is cached, so it may be applied to the canvas
+        many times without having to re-render.
+        (No longer scaling and tinting every time you click.)
+      Closes https://sourceforge.net/p/tuxpaint/bugs/147/
+      (h/t Andre Anckaert)
+
   * Improvements to "Eraser" tool:
     ------------------------------
     * Outline for circle-shaped erasers is now also circular.

src/tuxpaint.c

@@ -1904,6 +1904,7 @@ static int max_stamps[MAX_STAMP_GROUPS];
 static stamp_type **stamp_data[MAX_STAMP_GROUPS];
 
 static SDL_Surface *active_stamp;
+static SDL_Surface * current_stamp_cached = NULL;
 
 
 /**
@@ -2110,6 +2111,7 @@ static void update_stamp_xor(void);
 #endif
 
 static void set_active_stamp(void);
+static void clear_cached_stamp(void);
 
 static int calc_eraser_size(int which_eraser);
 static void do_eraser(int x, int y, int update);
@@ -4777,6 +4779,8 @@ static void mainloop(void)
                               color_hexes[cur_color][0],
                               color_hexes[cur_color][1],
                               color_hexes[cur_color][2]);
+                          else if (cur_tool == TOOL_STAMP)
+                            clear_cached_stamp();
                         }
                     }
                 }
@@ -7074,7 +7078,6 @@ static void tint_surface(SDL_Surface * tmp_surf, SDL_Surface * surf_ptr)
 }
 
 
-
 /**
  * Draw the current stamp onto the canvas.
  *
@@ -7084,21 +7087,29 @@ static void tint_surface(SDL_Surface * tmp_surf, SDL_Surface * surf_ptr)
 static void stamp_draw(int x, int y)
 {
   SDL_Rect dest;
-  SDL_Surface *tmp_surf, *surf_ptr, *final_surf;
+  SDL_Surface *scaled_surf, *tmp_surf, *surf_ptr;
   Uint32 amask;
   Uint8 r, g, b, a;
-  int xx, yy, dont_free_tmp_surf, base_x, base_y;
+  int xx, yy, base_x, base_y;
+  int dont_free_tmp_surf, dont_free_scaled_surf;
+
+  if (current_stamp_cached == NULL)
+    {
+      printf("Generating stamp image\n");
 
       Uint32(*getpixel) (SDL_Surface *, int, int);
       void (*putpixel) (SDL_Surface *, int, int, Uint32);
     
-  surf_ptr = active_stamp;
+      /* Shrink or grow it! */
+      scaled_surf = thumbnail(active_stamp, CUR_STAMP_W, CUR_STAMP_H, 0);
+      dont_free_scaled_surf = 0;
+    
+    
+      surf_ptr = scaled_surf;
     
       getpixel = getpixels[surf_ptr->format->BytesPerPixel];
     
-
       /* Create a temp surface to play with: */
-
       if (stamp_colorable(cur_stamp[stamp_group]) || stamp_tintable(cur_stamp[stamp_group]))
         {
           amask = ~(surf_ptr->format->Rmask | surf_ptr->format->Gmask | surf_ptr->format->Bmask);
@@ -7166,6 +7177,7 @@ static void stamp_draw(int x, int y)
         }
       else if (stamp_tintable(cur_stamp[stamp_group]))
         {
+          /* Tintable */
           if (stamp_data[stamp_group][cur_stamp[stamp_group]]->tinter == TINTER_VECTOR)
             vector_tint_surface(tmp_surf, surf_ptr);
           else
@@ -7177,8 +7189,17 @@ static void stamp_draw(int x, int y)
           tmp_surf = surf_ptr;
         }
 
-  /* Shrink or grow it! */
+      printf("Caching stamp\n");
-  final_surf = thumbnail(tmp_surf, CUR_STAMP_W, CUR_STAMP_H, 0);
+      current_stamp_cached = SDL_DisplayFormatAlpha(tmp_surf);
+    }
+  else
+    {
+      printf("Using cached stamp!\n");
+
+      tmp_surf = current_stamp_cached;
+      dont_free_tmp_surf = 1;
+      dont_free_scaled_surf = 1;
+    }
 
   /* Where it will go? */
   base_x = x - (CUR_STAMP_W + 1) / 2;
@@ -7187,7 +7208,7 @@ static void stamp_draw(int x, int y)
   /* And blit it! */
   dest.x = base_x;
   dest.y = base_y;
-  SDL_BlitSurface(final_surf, NULL, canvas, &dest);     /* FIXME: Conditional jump or move depends on uninitialised value(s) */
+  SDL_BlitSurface(tmp_surf, NULL, canvas, &dest);     /* FIXME: Conditional jump or move depends on uninitialised value(s) */
 
   update_canvas(x - (CUR_STAMP_W + 1) / 2,
                 y - (CUR_STAMP_H + 1) / 2, x + (CUR_STAMP_W + 1) / 2, y + (CUR_STAMP_H + 1) / 2);
@@ -7197,7 +7218,8 @@ static void stamp_draw(int x, int y)
   if (!dont_free_tmp_surf)
     SDL_FreeSurface(tmp_surf);
 
-  SDL_FreeSurface(final_surf);
+  if (!dont_free_scaled_surf)
+    SDL_FreeSurface(scaled_surf);
 }
 
 
@@ -7890,6 +7912,28 @@ static void loadstamp_finisher(stamp_type * sd, unsigned w, unsigned h, double r
 }
 
 
+/**
+ * Clear the currently-cached stamp image
+ * (what we blit to the canvas, so the stamp in its
+ * current orientation, scale, and color), since we'll
+ * need to generate something new based on a change
+ * (a new size, color, orientation, or a completely
+ * different stamp)
+ */
+static void clear_cached_stamp(void)
+{
+  if (current_stamp_cached != NULL)
+    {
+      printf("Clearing cached stamp\n");
+      SDL_FreeSurface(current_stamp_cached);
+      current_stamp_cached = NULL;
+    }
+  else
+    {
+      printf("No cached stamp to clear\n");
+    }
+}
+
 /**
  * FIXME
  */
@@ -8135,6 +8179,8 @@ static void set_active_stamp(void)
 #ifdef DEBUG
   printf("\n\n");
 #endif
+
+  clear_cached_stamp();
 }
 
 /**
@@ -13947,6 +13993,7 @@ static void cleanup(void)
       free(stamp_data[j]);
     }
   free_surface(&active_stamp);
+  free_surface(&current_stamp_cached);
 
   free_surface_array(img_brushes, num_brushes);
   free_surface_array(img_brushes_thumbs, num_brushes);