cairo-color-glyph-source-op.patch

From 99427c3f4f6ce7ce3c95c4caa4d2b8ff7c0093d9 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 12 Sep 2017 01:35:15 -0400
Subject: Handle SOURCE and CLEAR operators when painting color glyphs

In cairo, most operators are composited this way:

  ((src IN mask) OP dst) LERP_clip dst

but SOURCE and CLEAR operators are composited this way:

  (src OP dst) LERP_(clip IN mask) dst

(why is this not specified anywhere in the docs or source tree?)

With color glyphs, we were not special-casing SOURCE and CLEAR.
We do now.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=102661

diff --git a/src/cairo-surface.c b/src/cairo-surface.c
index 6f25bd7..35c63d7 100644
--- a/src/cairo-surface.c
+++ b/src/cairo-surface.c
@@ -2571,7 +2571,10 @@ composite_one_color_glyph (cairo_surface_t       *surface,
         pattern = cairo_pattern_create_for_surface ((cairo_surface_t *)glyph_surface);
         cairo_matrix_init_translate (&matrix, - x, - y);
         cairo_pattern_set_matrix (pattern, &matrix);
-        status = surface->backend->paint (surface, op, pattern, clip);
+	if (op == CAIRO_OPERATOR_SOURCE || op == CAIRO_OPERATOR_CLEAR)
+	  status = surface->backend->mask (surface, op, pattern, pattern, clip);
+	else
+	  status = surface->backend->paint (surface, op, pattern, clip);
     }
 
     return status;
-- 
cgit v0.10.2