src/cairo.[ch] doc/public/cairo-sections.txt: Add cairo_paint_with_alpha().

Fix segfault when mask == NULL.
test/mask.c test/mask-ref.png: Add testing of cairo_paint_with_alpha().
test/coverage.c test/coverage-ref.png: Remove ... it's not testing anything that mask doesn't test better.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/mask.c b/test/mask.c
index 20547b027..45765a67c 100644
--- a/test/mask.c
+++ b/test/mask.c
@@ -105,6 +105,12 @@ mask_polygon (cairo_t *cr, int x, int y)
 }
 
 static void
+mask_alpha (cairo_t *cr, int x, int y)
+{
+    cairo_paint_with_alpha (cr, 0.75);
+}
+
+static void
 mask_gradient (cairo_t *cr, int x, int y)
 {
     cairo_pattern_t *pattern;
@@ -158,6 +164,7 @@ static void (*pattern_funcs[])(cairo_t *cr, int x, int y) = {
 };
 
 static void (*mask_funcs[])(cairo_t *cr, int x, int y) = {
+    mask_alpha,
     mask_gradient,
     mask_polygon,
 };