[gimp] Bug 771851 - Vertical ruler shows artifacts if the status bar isn't showing

[Michael Natterer <mitch src gnome org>]

commit e909b77969ea29c882ee38b622c4507e7302c705
Author: Michael Natterer <mitch gimp org>
Date:   Thu Sep 22 23:03:53 2016 +0200

    Bug 771851 - Vertical ruler shows artifacts if the status bar isn't showing
    
    gimp_ruler_draw_pos(): when remembering the just drawn rectangle's
    position, don't just unconditionally overwrite the previous position's
    rectangle. Instead, if the previous position's rectangle has not been
    cleared yet (has a non-zero size), remember the union of old and new
    rectangle.
    
    Why this only happened to the vertical ruler with statusbar off is
    beyond my mind, it should have always produced artifacts.
    
    Unrelated: make sure the idle function is removed if we decide to
    immediately redraw in gimp_ruler_set_position().

 libgimpwidgets/gimpruler.c |   25 +++++++++++++++++++++----
 1 files changed, 21 insertions(+), 4 deletions(-)
---
diff --git a/libgimpwidgets/gimpruler.c b/libgimpwidgets/gimpruler.c
index c5dbd0e..28b428a 100644
--- a/libgimpwidgets/gimpruler.c
+++ b/libgimpwidgets/gimpruler.c
@@ -659,6 +659,12 @@ gimp_ruler_set_position (GimpRuler *ruler,
           (ABS (xdiff) > IMMEDIATE_REDRAW_THRESHOLD ||
            ABS (ydiff) > IMMEDIATE_REDRAW_THRESHOLD))
         {
+          if (priv->pos_redraw_idle_id)
+            {
+              g_source_remove (priv->pos_redraw_idle_id);
+              priv->pos_redraw_idle_id = 0;
+            }
+
           gimp_ruler_queue_pos_redraw (ruler);
         }
       else if (! priv->pos_redraw_idle_id)
@@ -1289,15 +1295,16 @@ gimp_ruler_queue_pos_redraw (GimpRuler *ruler)
   GimpRulerPrivate  *priv = GIMP_RULER_GET_PRIVATE (ruler);
   const GdkRectangle rect = gimp_ruler_get_pos_rect (ruler, priv->position);
 
-  gtk_widget_queue_draw_area (GTK_WIDGET(ruler),
+  gtk_widget_queue_draw_area (GTK_WIDGET (ruler),
                               rect.x,
                               rect.y,
                               rect.width,
                               rect.height);
 
-  if (priv->last_pos_rect.width != 0 || priv->last_pos_rect.height != 0)
+  if (priv->last_pos_rect.width  != 0 &&
+      priv->last_pos_rect.height != 0)
     {
-      gtk_widget_queue_draw_area (GTK_WIDGET(ruler),
+      gtk_widget_queue_draw_area (GTK_WIDGET (ruler),
                                   priv->last_pos_rect.x,
                                   priv->last_pos_rect.y,
                                   priv->last_pos_rect.width,
@@ -1349,7 +1356,17 @@ gimp_ruler_draw_pos (GimpRuler *ruler,
       cairo_fill (cr);
     }
 
-  priv->last_pos_rect = pos_rect;
+  if (priv->last_pos_rect.width  != 0 &&
+      priv->last_pos_rect.height != 0)
+    {
+      gdk_rectangle_union (&priv->last_pos_rect,
+                           &pos_rect,
+                           &priv->last_pos_rect);
+    }
+  else
+    {
+      priv->last_pos_rect = pos_rect;
+    }
 }
 
 static void