gl/msaa: Rely on the stencil buffer to cache the clip

When using a texture surface the depth/stencil buffer is private to
cairo so we can rely on the fact that any previously painted clip is
still valid.

We also only scissor when there's a previously painted clip on the
stencil buffer, otherwise we disable the scissor test. This fixes a few
test cases.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/cairo-gl-private.h b/src/cairo-gl-private.h
index 1da5084db..9366309af 100644
--- a/src/cairo-gl-private.h
+++ b/src/cairo-gl-private.h
@@ -177,6 +177,7 @@ struct _cairo_gl_surface {
     cairo_bool_t supports_msaa;
     cairo_bool_t msaa_active; /* Whether the multisampling
 			         framebuffer is active or not. */
+    cairo_clip_t *clip_on_stencil_buffer;
 
     int owns_tex;
     cairo_bool_t needs_update;