Move presum_gaussian to render.c

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/compton.c

@@ -403,54 +403,6 @@ run_fade(session_t *ps, win *w, unsigned steps) {
   }
 }
 
-// === Shadows ===
-
-/* precompute shadow corners and sides
-   to save time for large windows */
-
-static void
-presum_gaussian(session_t *ps, conv *map) {
-  int center = map->size / 2;
-  int opacity, x, y;
-
-  ps->cgsize = map->size;
-
-  if (ps->shadow_corner)
-    free(ps->shadow_corner);
-  if (ps->shadow_top)
-    free(ps->shadow_top);
-
-  ps->shadow_corner = cvalloc((ps->cgsize + 1) * (ps->cgsize + 1) * 26);
-  ps->shadow_top = cvalloc((ps->cgsize + 1) * 26);
-
-  for (x = 0; x <= ps->cgsize; x++) {
-    ps->shadow_top[25 * (ps->cgsize + 1) + x] = (unsigned char)
-      (sum_kernel(map, x - center, center, ps->cgsize * 2, ps->cgsize * 2) * 255.0);
-
-    for (opacity = 0; opacity < 25; opacity++) {
-      ps->shadow_top[opacity * (ps->cgsize + 1) + x] =
-        ps->shadow_top[25 * (ps->cgsize + 1) + x] * opacity / 25;
-    }
-
-    for (y = 0; y <= x; y++) {
-      ps->shadow_corner[25 * (ps->cgsize + 1) * (ps->cgsize + 1) + y * (ps->cgsize + 1) + x]
-        = (unsigned char)
-          (sum_kernel(map, x - center, y - center, ps->cgsize * 2, ps->cgsize * 2) * 255.0);
-      ps->shadow_corner[25 * (ps->cgsize + 1) * (ps->cgsize + 1) + x * (ps->cgsize + 1) + y]
-        = ps->shadow_corner[25 * (ps->cgsize + 1) * (ps->cgsize + 1) + y * (ps->cgsize + 1) + x];
-
-      for (opacity = 0; opacity < 25; opacity++) {
-        ps->shadow_corner[opacity * (ps->cgsize + 1) * (ps->cgsize + 1)
-                      + y * (ps->cgsize + 1) + x]
-          = ps->shadow_corner[opacity * (ps->cgsize + 1) * (ps->cgsize + 1)
-                          + x * (ps->cgsize + 1) + y]
-          = ps->shadow_corner[25 * (ps->cgsize + 1) * (ps->cgsize + 1)
-                          + y * (ps->cgsize + 1) + x] * opacity / 25;
-      }
-    }
-  }
-}
-
 // === Error handling ===
 
 static void
@@ -3851,9 +3803,6 @@ session_init(session_t *ps_old, int argc, char **argv) {
 
   init_atoms(ps);
 
-  ps->gaussian_map = gaussian_kernel(ps->o.shadow_radius);
-  presum_gaussian(ps, ps->gaussian_map);
-
   {
     xcb_render_create_picture_value_list_t pa = {
       .subwindowmode = IncludeInferiors,

src/render.c

@@ -1183,6 +1183,50 @@ static bool init_alpha_picts(session_t *ps) {
 	return true;
 }
 
+/// precompute shadow corners and sides to save time for large windows
+static void presum_gaussian(session_t *ps, conv *map) {
+	ps->cgsize = map->size;
+
+	const int center = map->size / 2;
+	const int r = ps->cgsize + 1;        // radius of the kernel
+	const int width = ps->cgsize * 2, height = ps->cgsize * 2;
+
+
+	if (ps->shadow_corner)
+		free(ps->shadow_corner);
+	if (ps->shadow_top)
+		free(ps->shadow_top);
+
+	// clang-format off
+	ps->shadow_corner = cvalloc(r*r*26);
+	ps->shadow_top = cvalloc(r*26);
+
+	for (int x = 0; x < r; x++) {
+		double sum = sum_kernel(map, x-center, center, width, height);
+		int tmp = ps->shadow_top[25*r+x] = (unsigned char)(sum*255.0);
+
+		for (int opacity = 0; opacity < 25; opacity++) {
+			ps->shadow_top[opacity*r+x] = tmp*opacity/25;
+		}
+	}
+
+	for (int x = 0; x < r; x++) {
+		for (int y = 0; y <= x; y++) {
+			double sum =
+			    sum_kernel(map, x-center, y-center, width, height);
+			ps->shadow_corner[25*r*r+y*r+x] = (unsigned char)(sum*255.0);
+			ps->shadow_corner[25*r*r+x*r+y] = ps->shadow_corner[25*r*r+y*r+x];
+
+			for (int opacity = 0; opacity < 25; opacity++) {
+				ps->shadow_corner[opacity*r*r+y*r+x] =
+				ps->shadow_corner[opacity*r*r+x*r+y] =
+				    ps->shadow_corner[25*r*r+y*r+x]*opacity/25;
+			}
+		}
+	}
+	// clang-format on
+}
+
 bool init_render(session_t *ps) {
 	// Initialize OpenGL as early as possible
 	if (bkend_use_glx(ps)) {
@@ -1232,6 +1276,9 @@ bool init_render(session_t *ps) {
 			return false;
 	}
 
+	ps->gaussian_map = gaussian_kernel(ps->o.shadow_radius);
+	presum_gaussian(ps, ps->gaussian_map);
+
 	ps->black_picture = solid_picture(ps, true, 1, 0, 0, 0);
 	ps->white_picture = solid_picture(ps, true, 1, 1, 1, 1);