From cc579560088bee8d7c6366fb4ccffc461c3d2236 Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Sun, 10 Mar 2024 19:54:08 -0400
Subject: [PATCH] offload: Fix handling of clips

When we are inside a non-representable clip, we can't offload. The
reason for this is that the renderer will offscreen due to that
clip, and then the hole we need to punch will end up in the offscreen
and not in the main surface where we need it.

Fixes: #6499
---
 gsk/gskoffload.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/gsk/gskoffload.c b/gsk/gskoffload.c
index 31103f691e..b697e321af 100644
--- a/gsk/gskoffload.c
+++ b/gsk/gskoffload.c
@@ -38,7 +38,7 @@ typedef struct
   guint is_rectilinear     : 1;
   guint is_fully_contained : 1;
   guint is_empty           : 1;
-  guint is_complex         : 1;
+  guint is_complex         : 1; /* Inside a non-representable clip, even if fully contained */
 } Clip;
 
 struct _GskOffload
@@ -225,10 +225,13 @@ static void
 push_rect_clip (GskOffload           *self,
                 const GskRoundedRect *rect)
 {
+  Clip *current_clip = self->clips->data;
   Clip *clip = g_new0 (Clip, 1);
+
   clip->rect = *rect;
   clip->is_rectilinear = gsk_rounded_rect_is_rectilinear (rect);
   clip->is_empty = (rect->bounds.size.width == 0 || rect->bounds.size.height == 0);
+  clip->is_complex = current_clip && current_clip->is_complex;
 
   self->clips = g_slist_prepend (self->clips, clip);
   self->current_clip = self->clips->data;
@@ -249,6 +252,7 @@ push_contained_clip (GskOffload *self)
   clip->rect = current_clip->rect;
   clip->is_rectilinear = TRUE;
   clip->is_fully_contained = TRUE;
+  clip->is_complex = current_clip && current_clip->is_complex;
 
   self->clips = g_slist_prepend (self->clips, clip);
   self->current_clip = self->clips->data;
@@ -517,21 +521,21 @@ visit_node (GskOffload    *self,
               push_empty_clip (self);
             else if (result == GSK_INTERSECTION_NONEMPTY)
               push_rect_clip (self, &intersection);
+            else if (gsk_rounded_rect_contains_rect (&self->current_clip->rect, &transformed_clip.bounds))
+              push_rect_clip (self, &transformed_clip);
             else
-              goto complex_clip;
-            visit_node (self, gsk_rounded_clip_node_get_child (node));
-            pop_clip (self);
+              push_complex_clip (self);
           }
         else
           {
-complex_clip:
             if (gsk_rounded_rect_contains_rect (&self->current_clip->rect, &transformed_clip.bounds))
               push_rect_clip (self, &transformed_clip);
             else
               push_complex_clip (self);
-            visit_node (self, gsk_rounded_clip_node_get_child (node));
-            pop_clip (self);
           }
+
+        visit_node (self, gsk_rounded_clip_node_get_child (node));
+        pop_clip (self);
       }
       break;
 
@@ -568,6 +572,12 @@ complex_clip:
                                "Can't offload subsurface %p: clipped",
                                subsurface);
           }
+        else if (self->current_clip->is_complex)
+          {
+            GDK_DISPLAY_DEBUG (gdk_surface_get_display (self->surface), OFFLOAD,
+                               "Can't offload subsurface %p: inside non-representable clip",
+                               subsurface);
+          }
         else if (self->transforms &&
                  gsk_transform_get_category ((GskTransform *)self->transforms->data) < GSK_TRANSFORM_CATEGORY_2D_AFFINE)
           {