[gimp/gimp-2-8] Bug 663582 - Brush outline is too slow

[Michael Natterer <mitch src gnome org>]

commit b03591e4055ccf32631069cf95067a09bf698e42
Author: Michael Natterer <mitch gimp org>
Date:   Thu Oct 4 20:42:13 2012 +0200

    Bug 663582 - Brush outline is too slow
    
    Keep around the last drawing time in GimpDrawTool and make sure we
    draw at least with a frame rate of around 20 fps, which feels
    reasonably non-laggy.
    (cherry picked from commit fd4e220c28d42a3b0169df21dc803f5601a6691e)

 app/tools/gimpdrawtool.c |   20 +++++++++++++++++---
 app/tools/gimpdrawtool.h |   11 ++++++-----
 2 files changed, 23 insertions(+), 8 deletions(-)
---
diff --git a/app/tools/gimpdrawtool.c b/app/tools/gimpdrawtool.c
index 531e46c..087c34f 100644
--- a/app/tools/gimpdrawtool.c
+++ b/app/tools/gimpdrawtool.c
@@ -59,8 +59,9 @@
 #include "gimpdrawtool.h"
 
 
-#define DRAW_TIMEOUT 4
-#define USE_TIMEOUT  1
+#define DRAW_TIMEOUT           4
+#define USE_TIMEOUT            1
+#define MINIMUM_DRAW_INTERVAL 50 /* 50 microseconds == 20 fps */
 
 
 static void          gimp_draw_tool_dispose      (GObject          *object);
@@ -190,12 +191,21 @@ gimp_draw_tool_draw_timeout (GimpDrawTool *draw_tool)
 static void
 gimp_draw_tool_draw (GimpDrawTool *draw_tool)
 {
+  guint64 now = g_get_monotonic_time ();
+
   if (draw_tool->display &&
       draw_tool->paused_count == 0 &&
-      ! draw_tool->draw_timeout)
+      (! draw_tool->draw_timeout ||
+       (now - draw_tool->last_draw_time) > MINIMUM_DRAW_INTERVAL))
     {
       GimpDisplayShell *shell = gimp_display_get_shell (draw_tool->display);
 
+      if (draw_tool->draw_timeout)
+        {
+          g_source_remove (draw_tool->draw_timeout);
+          draw_tool->draw_timeout = 0;
+        }
+
       gimp_draw_tool_undraw (draw_tool);
 
       GIMP_DRAW_TOOL_GET_CLASS (draw_tool)->draw (draw_tool);
@@ -216,6 +226,8 @@ gimp_draw_tool_draw (GimpDrawTool *draw_tool)
 
       if (draw_tool->item)
         gimp_display_shell_add_tool_item (shell, draw_tool->item);
+
+      draw_tool->last_draw_time = now;
     }
 }
 
@@ -275,6 +287,8 @@ gimp_draw_tool_stop (GimpDrawTool *draw_tool)
       draw_tool->draw_timeout = 0;
     }
 
+  draw_tool->last_draw_time = 0;
+
   draw_tool->display = NULL;
 }
 
diff --git a/app/tools/gimpdrawtool.h b/app/tools/gimpdrawtool.h
index 705fae6..4cf3c38 100644
--- a/app/tools/gimpdrawtool.h
+++ b/app/tools/gimpdrawtool.h
@@ -42,12 +42,13 @@ struct _GimpDrawTool
 {
   GimpTool        parent_instance;
 
-  GimpDisplay    *display;      /*  The display we are drawing to (may be
-                                 *  a different one than tool->display)
-                                 */
+  GimpDisplay    *display;        /*  The display we are drawing to (may be
+                                   *  a different one than tool->display)
+                                   */
 
-  gint            paused_count; /*  count to keep track of multiple pauses  */
-  guint           draw_timeout; /*  draw delay timeout ID                   */
+  gint            paused_count;   /*  count to keep track of multiple pauses  */
+  guint           draw_timeout;   /*  draw delay timeout ID                   */
+  guint64         last_draw_time; /*  time of last draw(), monotonically      */
 
   GimpCanvasItem *preview;
   GimpCanvasItem *item;