[gimp] app: in GimpLevelsTool, calculate histogram asynchronously

[N/A <ell src gnome org>]

commit b0ce645fe212ab15f24fd4c1c4b256102ea07113
Author: Ell <ell_se yahoo com>
Date:   Fri May 11 12:08:39 2018 -0400

    app: in GimpLevelsTool, calculate histogram asynchronously
    
    In GimpLevelsTool, calculate the histogram of the target drawable
    asynchronously, rather than synchronously, to avoid blocking the UI
    while the histogram is calculated.

 app/tools/gimplevelstool.c |   13 ++++++++++---
 app/tools/gimplevelstool.h |    1 +
 2 files changed, 11 insertions(+), 3 deletions(-)
---
diff --git a/app/tools/gimplevelstool.c b/app/tools/gimplevelstool.c
index eae3fa0..5c5fba7 100644
--- a/app/tools/gimplevelstool.c
+++ b/app/tools/gimplevelstool.c
@@ -32,6 +32,7 @@
 #include "operations/gimplevelsconfig.h"
 #include "operations/gimpoperationlevels.h"
 
+#include "core/gimpasync.h"
 #include "core/gimpdrawable.h"
 #include "core/gimpdrawable-histogram.h"
 #include "core/gimperror.h"
@@ -168,6 +169,7 @@ gimp_levels_tool_finalize (GObject *object)
   GimpLevelsTool *tool = GIMP_LEVELS_TOOL (object);
 
   g_clear_object (&tool->histogram);
+  g_clear_object (&tool->histogram_async);
 
   G_OBJECT_CLASS (parent_class)->finalize (object);
 }
@@ -199,9 +201,11 @@ gimp_levels_tool_initialize (GimpTool     *tool,
                  NULL);
 
   g_clear_object (&l_tool->histogram);
+  g_clear_object (&l_tool->histogram_async);
   l_tool->histogram = gimp_histogram_new (config->linear);
 
-  gimp_drawable_calculate_histogram (drawable, l_tool->histogram, FALSE);
+  l_tool->histogram_async = gimp_drawable_calculate_histogram_async (
+    drawable, l_tool->histogram, FALSE);
   gimp_histogram_view_set_histogram (GIMP_HISTOGRAM_VIEW (l_tool->histogram_view),
                                      l_tool->histogram);
 
@@ -687,10 +691,11 @@ gimp_levels_tool_config_notify (GimpFilterTool   *filter_tool,
                      NULL);
 
       g_clear_object (&levels_tool->histogram);
+      g_clear_object (&levels_tool->histogram_async);
       levels_tool->histogram = gimp_histogram_new (levels_config->linear);
 
-      gimp_drawable_calculate_histogram (GIMP_TOOL (filter_tool)->drawable,
-                                         levels_tool->histogram, FALSE);
+      levels_tool->histogram_async = gimp_drawable_calculate_histogram_async (
+        GIMP_TOOL (filter_tool)->drawable, levels_tool->histogram, FALSE);
       gimp_histogram_view_set_histogram (GIMP_HISTOGRAM_VIEW (levels_tool->histogram_view),
                                          levels_tool->histogram);
     }
@@ -996,6 +1001,8 @@ levels_stretch_callback (GtkWidget      *widget,
   GimpTool       *tool        = GIMP_TOOL (levels_tool);
   GimpFilterTool *filter_tool = GIMP_FILTER_TOOL (levels_tool);
 
+  gimp_async_wait (levels_tool->histogram_async);
+
   gimp_levels_config_stretch (GIMP_LEVELS_CONFIG (filter_tool->config),
                               levels_tool->histogram,
                               gimp_drawable_is_rgb (tool->drawable));
diff --git a/app/tools/gimplevelstool.h b/app/tools/gimplevelstool.h
index 6d62b24..4f98114 100644
--- a/app/tools/gimplevelstool.h
+++ b/app/tools/gimplevelstool.h
@@ -39,6 +39,7 @@ struct _GimpLevelsTool
 
   /* dialog */
   GimpHistogram  *histogram;
+  GimpAsync      *histogram_async;
 
   GtkWidget      *channel_menu;