[gimp] app: use FAST filter when painting xfer surface

[N/A <ell src gnome org>]

commit 36258a671a04336260b1154128f8ff2cd9b85673
Author: Ell <ell_se yahoo com>
Date:   Sat Dec 9 10:34:48 2017 -0500

    app: use FAST filter when painting xfer surface
    
    Use CAIRO_FILTER_FAST when painting the xfer surface to the
    screen.  This notably improves performance when the canvas is
    rotated, at the cost of lower filtering quality.

 app/display/gimpdisplayshell-render.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-render.c b/app/display/gimpdisplayshell-render.c
index 8032087..9b03231 100644
--- a/app/display/gimpdisplayshell-render.c
+++ b/app/display/gimpdisplayshell-render.c
@@ -333,6 +333,7 @@ gimp_display_shell_render (GimpDisplayShell *shell,
   cairo_set_source_surface (cr, xfer,
                             x - xfer_src_x,
                             y - xfer_src_y);
+  cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_FAST);
   cairo_paint (cr);
 
   if (shell->mask)