[gnome-music] albumartcache: Rely on cairo for cover scaling

[Carlos Garnacho <carlosg src gnome org>]

commit 1f013e98bb7a7726be1d84e2403103847c9cd7bd
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Nov 6 21:31:33 2016 +0100

    albumartcache: Rely on cairo for cover scaling
    
    This avoids creating the temporary pixbuf with the scaled content,
    just make the pattern contain the unmodified pixbuf data, and
    perform the scaling in cairo.

 gnomemusic/albumartcache.py |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/gnomemusic/albumartcache.py b/gnomemusic/albumartcache.py
index 3064152..eae2927 100644
--- a/gnomemusic/albumartcache.py
+++ b/gnomemusic/albumartcache.py
@@ -62,10 +62,6 @@ def _make_icon_frame(pixbuf, art_size=None, scale=1):
         w = art_size.width * scale
         h = int(art_size.height * ratio * scale)
 
-    new_pixbuf = pixbuf.scale_simple(w - border * 2,
-                                     h - border * 2,
-                                     GdkPixbuf.InterpType.HYPER)
-
     surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, w, h)
     ctx = cairo.Context(surface)
 
@@ -84,9 +80,17 @@ def _make_icon_frame(pixbuf, art_size=None, scale=1):
     ctx.set_source_rgb(1, 1, 1)
     ctx.fill()
 
+    matrix = cairo.Matrix()
+    matrix.scale(pixbuf.get_width() / (w - border * 2),
+                 pixbuf.get_height() / (h - border * 2))
+    matrix.translate(-border, -border)
+
     # paste the scaled pixbuf in the center
-    Gdk.cairo_set_source_pixbuf(ctx, new_pixbuf, border, border)
-    ctx.paint()
+    Gdk.cairo_set_source_pixbuf(ctx, pixbuf, 0, 0)
+    pattern = ctx.get_source()
+    pattern.set_matrix(matrix)
+    ctx.rectangle(border, border, w - border * 2, h - border * 2)
+    ctx.fill()
 
     border_pixbuf = Gdk.pixbuf_get_from_surface(surface, 0, 0, w, h)