[gimp] app: throttle GimpCanvasProgress updates

[N/A <ell src gnome org>]

commit dc1852049e95aa11d6be0b0f5a0d1a3f4f2cec79
Author: Ell <ell_se yahoo com>
Date:   Fri Mar 16 04:23:15 2018 -0400

    app: throttle GimpCanvasProgress updates
    
    Avoid redrawing GimpCanvasProgress items upon
    GimpProgress::set_value() if a minimal amount of time hasn't passed
    since the last call.  This notably improves performance of
    frequently-updated GimpCanvasProgress items.

 app/display/gimpcanvasprogress.c |   27 +++++++++++++++++++++------
 1 files changed, 21 insertions(+), 6 deletions(-)
---
diff --git a/app/display/gimpcanvasprogress.c b/app/display/gimpcanvasprogress.c
index e275029..24fad4a 100644
--- a/app/display/gimpcanvasprogress.c
+++ b/app/display/gimpcanvasprogress.c
@@ -37,8 +37,10 @@
 #include "gimpdisplayshell.h"
 
 
-#define BORDER   5
-#define RADIUS  20
+#define BORDER                5
+#define RADIUS               20
+
+#define MIN_UPDATE_INTERVAL  50000 /* microseconds */
 
 
 enum
@@ -60,6 +62,8 @@ struct _GimpCanvasProgressPrivate
 
   gchar            *text;
   gdouble           value;
+
+  guint64           last_update_time;
 };
 
 #define GET_PRIVATE(progress) \
@@ -350,8 +354,12 @@ gimp_canvas_progress_start (GimpProgress *progress,
                             gboolean      cancellable,
                             const gchar  *message)
 {
+  GimpCanvasProgressPrivate *private = GET_PRIVATE (progress);
+
   gimp_canvas_progress_set_text (progress, message);
 
+  private->last_update_time = g_get_monotonic_time ();
+
   return progress;
 }
 
@@ -399,15 +407,22 @@ gimp_canvas_progress_set_value (GimpProgress *progress,
 
   if (percentage != private->value)
     {
-      cairo_region_t *region;
+      guint64 time = g_get_monotonic_time ();
 
       private->value = percentage;
 
-      region = gimp_canvas_item_get_extents (GIMP_CANVAS_ITEM (progress));
+      if (time - private->last_update_time >= MIN_UPDATE_INTERVAL)
+        {
+          cairo_region_t *region;
+
+          private->last_update_time = time;
+
+          region = gimp_canvas_item_get_extents (GIMP_CANVAS_ITEM (progress));
 
-      _gimp_canvas_item_update (GIMP_CANVAS_ITEM (progress), region);
+          _gimp_canvas_item_update (GIMP_CANVAS_ITEM (progress), region);
 
-      cairo_region_destroy (region);
+          cairo_region_destroy (region);
+        }
     }
 }