Cache the background in the nice clock

Render the svg only one time in a internal surface to improve performance

Signed-off-by: Gonzalo Odiard <gonzalo@laptop.org>

1 files changed, 19 insertions, 7 deletions

diff --git a/clock.py b/clock.py
index 3e66185..bb793cb 100755
--- a/clock.py
+++ b/clock.py
@@ -525,6 +525,9 @@ class ClockFace(gtk.DrawingArea):
         # Black
         self._COLOR_BLACK = "#000000"
 
+        # cache backgrounds
+        self._nice_background_cache = None
+
         # gtk.Widget signals
         self.connect("expose-event", self._expose_cb)
         self.connect("size-allocate", self._size_allocate_cb)
@@ -737,13 +740,22 @@ class ClockFace(gtk.DrawingArea):
         """
         # We transform the background SVG
         cr = self.window.cairo_create()
-        scale_x = self._radius * 2.0 / self._svg_handle.props.width
-        scale_y = self._radius * 2.0 / self._svg_handle.props.height
-        matrix = cairo.Matrix(xx=scale_x, yy=scale_y,
-                              x0=self._center_x - self._radius,
-                              y0=self._center_y - self._radius)
-        cr.transform(matrix)
-        self._svg_handle.render_cairo(cr)
+
+        if self._nice_background_cache == None:
+            self._nice_background_cache = cr.get_target().create_similar(
+                    cairo.CONTENT_COLOR_ALPHA, self._radius * 2,
+                    self._radius * 2)
+            cache_ctx = cairo.Context(self._nice_background_cache)
+            scale_x = self._radius * 2.0 / self._svg_handle.props.width
+            scale_y = self._radius * 2.0 / self._svg_handle.props.height
+            matrix = cairo.Matrix(xx=scale_x, yy=scale_y)
+            cache_ctx.transform(matrix)
+            self._svg_handle.render_cairo(cache_ctx)
+
+        cr.translate(self._center_x - self._radius,
+                self._center_y - self._radius)
+        cr.set_source_surface(self._nice_background_cache)
+        cr.paint()
 
     def _draw_nice_clock(self):
         """Draw the nice clock.