[goocanvas/goocanvas-2.0] fixed bug painting images with alpha < 1

[Damon Chaplin <damon src gnome org>]

commit 5f5470f9a5dfcbcfbc6623592ec2f2f5cbb5472e
Author: Damon Chaplin <Damon A Chaplin gmail com>
Date:   Fri Dec 16 15:06:17 2016 +0000

    fixed bug painting images with alpha < 1

 ChangeLog            |    6 ++++++
 src/goocanvasimage.c |   20 +++++++-------------
 2 files changed, 13 insertions(+), 13 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index d042e78..1db84c6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2016-12-16  Damon Chaplin  <damon gnome org>
+
+       * src/goocanvasimage.c (goo_canvas_image_paint): use cairo_clip() when
+       calling cairo_paint_with_alpha() otherwise it gets messed up.
+       (the flowers in the demo were sometimes painted incorrectly.)
+
 2016-12-15  Damon Chaplin  <damon gnome org>
 
        * src/goocanvastext.c (goo_canvas_text_get_natural_extents):
diff --git a/src/goocanvasimage.c b/src/goocanvasimage.c
index e470126..28c948f 100644
--- a/src/goocanvasimage.c
+++ b/src/goocanvasimage.c
@@ -502,8 +502,6 @@ goo_canvas_image_paint (GooCanvasItemSimple   *simple,
   if (!image_data->pattern)
     return;
 
-#if 1
-
   /* scale-to-fit means a simple scale, not keeping the aspect ratio.
      This does not need to consider the units used. */ 
   if (priv->scale_to_fit)
@@ -541,18 +539,14 @@ goo_canvas_image_paint (GooCanvasItemSimple   *simple,
   /* To have better performance, we don't use cairo_paint_with_alpha if
    * the image is not transparent at all. */
   if (priv->alpha != 1.0)
-    cairo_paint_with_alpha (cr, priv->alpha);
+    {
+      cairo_clip (cr);
+      cairo_paint_with_alpha (cr, priv->alpha);
+    }
   else
-    cairo_fill (cr);
-#else
-  /* Using cairo_paint() used to be much slower than cairo_fill(), though
-     they seem similar now. I'm not sure if it matters which we use. */
-  cairo_matrix_init_translate (&matrix, -image_data->x, -image_data->y);
-  cairo_pattern_set_matrix (image_data->pattern, &matrix);
-  goo_canvas_style_set_fill_options (simple->simple_data->style, cr);
-  cairo_set_source (cr, image_data->pattern);
-  cairo_paint (cr);
-#endif
+    {
+      cairo_fill (cr);
+    }
 }