Merge branch 'wip/otte/clear-clear' into 'master'

Clear is_clear flag on unmap_image()

See merge request cairo/cairo!487

src/cairo-image-surface.c

@@ -854,6 +854,10 @@ cairo_int_status_t
 _cairo_image_surface_unmap_image (void *abstract_surface,
 				  cairo_image_surface_t *image)
 {
+    cairo_image_surface_t *surface = abstract_surface;
+
+    surface->base.is_clear &= image->base.is_clear;
+
     cairo_surface_finish (&image->base);
     cairo_surface_destroy (&image->base);
 

test/map-to-image.c

@@ -115,6 +115,38 @@ bit (cairo_t *cr, int width, int height)
     return CAIRO_TEST_SUCCESS;
 }
 
+static cairo_test_status_t
+clear (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *surface;
+    cairo_pattern_t *pattern;
+    cairo_rectangle_int_t extents;
+    cairo_t *cr2;
+
+    extents.x = extents.y = extents.width = extents.height = 1;
+
+    /* Fill background red */
+    cairo_set_source_rgb (cr, 1, 0, 0);
+    cairo_paint (cr);
+
+    /* Get clear image */
+    cairo_push_group (cr);
+
+    surface = cairo_surface_map_to_image (cairo_get_group_target (cr), &extents);
+    cr2 = cairo_create (surface);
+    cairo_set_source_rgb (cr2, 0, 0, 1);
+    cairo_paint (cr2);
+    cairo_destroy (cr2);
+    cairo_surface_unmap_image (cairo_get_group_target (cr), surface);
+
+    pattern = cairo_pop_group (cr);
+    /* all green */
+    cairo_set_source_rgb (cr, 0, 1, 0);
+    cairo_mask (cr, pattern);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
 static cairo_test_status_t
 fill (cairo_t *cr, int width, int height)
 {
@@ -150,6 +182,12 @@ CAIRO_TEST (map_bit_to_image,
 	    "target=raster", /* requirements */
 	    WIDTH, HEIGHT,
 	    NULL, bit)
+CAIRO_TEST (map_clear_to_image,
+	    "Test mapping a clear surface to an image and modifying it externally marks it as not clear",
+	    "image", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, clear)
 CAIRO_TEST (map_to_image_fill,
 	    "Test mapping a surface to an image and modifying it externally",
 	    "image", /* keywords */