[shotwell] Don't call gdk_cairo_create() outside of begin/end_paint: Bug #732118

[Jim Nelson <jnelson src gnome org>]

commit a699d97b80dfb1af11cd89957d65bdad4f1ff594
Author: Jim Nelson <jim yorba org>
Date:   Mon Jun 23 11:46:46 2014 -0700

    Don't call gdk_cairo_create() outside of begin/end_paint: Bug #732118
    
    Interactive pan/zoom would paint directly to GDK window's Cairo
    context outside of a draw() signal.  A recent change to GTK+ in 3.13.3
    removes this functionality and requires wrapping this code between
    gdk_window_begin_paint_region() and gdk_window_end_paint().  It's far
    easier to simply queue a redraw and let the usual draw handler deal
    with it.
    
    See:
    https://mail.gnome.org/archives/gtk-devel-list/2014-June/msg00010.html

 src/Page.vala |   14 ++------------
 1 files changed, 2 insertions(+), 12 deletions(-)
---
diff --git a/src/Page.vala b/src/Page.vala
index 57e5b4a..1eecacf 100644
--- a/src/Page.vala
+++ b/src/Page.vala
@@ -1943,12 +1943,6 @@ public abstract class SinglePhotoPage : Page {
         
         add(viewport);
 
-        // We used to disable GTK double buffering here.  We've had to reenable it
-        // due to this bug: http://redmine.yorba.org/issues/4775 .  
-        //
-        // all painting happens in pixmap, and is sent to the window wholesale in on_canvas_expose
-        // canvas.set_double_buffered(false);
-        
         canvas.add_events(Gdk.EventMask.EXPOSURE_MASK | Gdk.EventMask.STRUCTURE_MASK 
             | Gdk.EventMask.SUBSTRUCTURE_MASK);
         
@@ -2016,7 +2010,6 @@ public abstract class SinglePhotoPage : Page {
 
     protected void on_interactive_zoom(ZoomState interactive_zoom_state) {
         assert(is_zoom_supported());
-        Cairo.Context canvas_ctx = Gdk.cairo_create(canvas.get_window());
         
         set_source_color_from_string(pixmap_ctx, "#000");
         pixmap_ctx.paint();
@@ -2026,13 +2019,11 @@ public abstract class SinglePhotoPage : Page {
         render_zoomed_to_pixmap(interactive_zoom_state);
         zoom_high_quality = old_quality_setting;
         
-        canvas_ctx.set_source_surface(pixmap, 0, 0);
-        canvas_ctx.paint();
+        canvas.queue_draw();
     }
 
     protected void on_interactive_pan(ZoomState interactive_zoom_state) {
         assert(is_zoom_supported());
-        Cairo.Context canvas_ctx = Gdk.cairo_create(canvas.get_window());
         
         set_source_color_from_string(pixmap_ctx, "#000");
         pixmap_ctx.paint();
@@ -2042,8 +2033,7 @@ public abstract class SinglePhotoPage : Page {
         render_zoomed_to_pixmap(interactive_zoom_state);
         zoom_high_quality = old_quality_setting;
         
-        canvas_ctx.set_source_surface(pixmap, 0, 0);
-        canvas_ctx.paint();
+        canvas.queue_draw();
     }
 
     protected virtual bool is_zoom_supported() {