[gtk/wip/chergert/macos-iosurface] use bigger tiles for transparent edges (shadows)

[Christian Hergert <chergert src gnome org>]

commit d40cabb21ed750199561adcaeb7ddb1adeec54cc
Author: Christian Hergert <christian hergert me>
Date:   Fri Feb 11 03:46:38 2022 -0800

    use bigger tiles for transparent edges (shadows)

 gdk/macos/GdkMacosLayer.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)
---
diff --git a/gdk/macos/GdkMacosLayer.c b/gdk/macos/GdkMacosLayer.c
index d1aa1431f0..b4b7b905a3 100644
--- a/gdk/macos/GdkMacosLayer.c
+++ b/gdk/macos/GdkMacosLayer.c
@@ -26,6 +26,7 @@
 @implementation GdkMacosLayer
 
 #define TILE_MAX_SIZE 128
+#define TILE_EDGE_MAX_SIZE 512
 
 static CGAffineTransform flipTransform;
 static gboolean hasFlipTransform;
@@ -71,7 +72,8 @@ tiler_init (Tiler                *tiler,
 
 static gboolean
 tiler_next (Tiler                 *tiler,
-            cairo_rectangle_int_t *tile)
+            cairo_rectangle_int_t *tile,
+            int                    max_size)
 {
   if (tiler->finished)
     return FALSE;
@@ -92,19 +94,19 @@ tiler_next (Tiler                 *tiler,
   /* If the next rectangle is too tall, slice the bottom off to
    * leave just the height we want into tiler->stash.
    */
-  if (tiler->rect.height > TILE_MAX_SIZE)
+  if (tiler->rect.height > max_size)
     {
       tiler->stash = tiler->rect;
-      tiler->stash.y += TILE_MAX_SIZE;
-      tiler->stash.height -= TILE_MAX_SIZE;
-      tiler->rect.height = TILE_MAX_SIZE;
+      tiler->stash.y += max_size;
+      tiler->stash.height -= max_size;
+      tiler->rect.height = max_size;
     }
 
   /* Now we can take the next horizontal slice */
   tile->x = tiler->rect.x;
   tile->y = tiler->rect.y;
   tile->height = tiler->rect.height;
-  tile->width = MIN (TILE_MAX_SIZE, tiler->rect.width);
+  tile->width = MIN (max_size, tiler->rect.width);
 
   tiler->rect.x += tile->width;
   tiler->rect.width -= tile->width;
@@ -236,6 +238,7 @@ fromCGRect (const CGRect rect)
   GArray *ar;
   cairo_region_t *transparent;
   cairo_rectangle_int_t rect;
+  int max_size;
 
   if (!self->_inSwapBuffer)
     return;
@@ -252,9 +255,20 @@ fromCGRect (const CGRect rect)
 
   self->_opaque = cairo_region_is_empty (transparent);
 
+  /* If we have transparent borders around the opaque region, then
+   * we are okay with a bit larger tiles since they don't change
+   * all that much and are generally small in width.
+   */
+  if (!self->_opaque &&
+      self->_opaqueRegion &&
+      !cairo_region_is_empty (self->_opaqueRegion))
+    max_size = TILE_EDGE_MAX_SIZE;
+  else
+    max_size = TILE_MAX_SIZE;
+
   /* Track transparent children */
   tiler_init (&tiler, transparent);
-  while (tiler_next (&tiler, &rect))
+  while (tiler_next (&tiler, &rect, max_size))
     {
       TileInfo *info;
 
@@ -269,7 +283,7 @@ fromCGRect (const CGRect rect)
 
   /* Track opaque children */
   tiler_init (&tiler, self->_opaqueRegion);
-  while (tiler_next (&tiler, &rect))
+  while (tiler_next (&tiler, &rect, TILE_MAX_SIZE))
     {
       TileInfo *info;