From 5c53dd5d6e61db735c471ff81654a5302c33825e Mon Sep 17 00:00:00 2001
From: Christian Hergert <chergert@redhat.com>
Date: Fri, 30 Sep 2016 17:04:48 -0700
Subject: [PATCH] visualizer-view: avoid overscroll upon zoom change

When changing the zoom (zooming out), we could potentially
let the scrollbar be past the end. This looks pretty bad when
the GtkWindow doesn't clip correctly.

This just adjusts things so we push ourselves back into the
visible area.
---
 lib/sp-visualizer-view.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/sp-visualizer-view.c b/lib/sp-visualizer-view.c
index b0b95654..4be1efee 100644
--- a/lib/sp-visualizer-view.c
+++ b/lib/sp-visualizer-view.c
@@ -130,6 +130,9 @@ sp_visualizer_view_notify_zoom (SpVisualizerView *self,
   gint64 begin_time = 0.0;
   gint64 end_time;
   gdouble zoom;
+  gdouble page_size;
+  gdouble upper;
+  gdouble value;
 
   g_assert (SP_IS_VISUALIZER_VIEW (self));
   g_assert (SP_IS_ZOOM_MANAGER (zoom_manager));
@@ -144,6 +147,15 @@ sp_visualizer_view_notify_zoom (SpVisualizerView *self,
   sp_visualizer_view_set_time_range (self, begin_time, end_time);
   gtk_adjustment_set_page_size (priv->scroll_adjustment, end_time - begin_time);
 
+  g_object_get (priv->scroll_adjustment,
+                "page-size", &page_size,
+                "upper", &upper,
+                "value", &value,
+                NULL);
+
+  if (value + page_size > upper)
+    gtk_adjustment_set_value (priv->scroll_adjustment, upper - page_size);
+
   if (priv->reader != NULL)
     {
       gint64 real_range;