[gnome-builder/wip/minimap2] minimap: handle buffers that do not fill the minimap

[Christian Hergert <chergert src gnome org>]

commit fea5b08c6ad82c7dd246da6422af29e7229620d8
Author: Christian Hergert <christian hergert me>
Date:   Tue Apr 21 16:44:02 2015 -0700

    minimap: handle buffers that do not fill the minimap
    
    This will help keep the mouse cursor on the scrubber widget.

 libide/ide-source-map.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/libide/ide-source-map.c b/libide/ide-source-map.c
index 2e5edd2..52ef6f6 100644
--- a/libide/ide-source-map.c
+++ b/libide/ide-source-map.c
@@ -478,6 +478,7 @@ ide_source_map__overlay_box_motion_notify_event (IdeSourceMap   *self,
       GdkRectangle rect;
       GtkTextIter iter;
       gdouble ratio;
+      gint child_height;
       gint x;
       gint y;
 
@@ -488,13 +489,14 @@ ide_source_map__overlay_box_motion_notify_event (IdeSourceMap   *self,
                                         GTK_WIDGET (self->child_view),
                                         event->x, event->y, &x, &y);
 
-      y = CLAMP (y, child_alloc.y, child_alloc.y + child_alloc.height) - child_alloc.y;
-      ratio = (gdouble)y / (gdouble)child_alloc.height;
-
       buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (self->child_view));
       gtk_text_buffer_get_end_iter (buffer, &iter);
       gtk_text_view_get_iter_location (GTK_TEXT_VIEW (self->child_view), &iter, &rect);
 
+      child_height = MIN (child_alloc.height, (rect.y + rect.height));
+
+      y = CLAMP (y, child_alloc.y, child_alloc.y + child_height) - child_alloc.y;
+      ratio = (gdouble)y / (gdouble)child_height;
       y = (rect.y + rect.height) * ratio;
 
       gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (self->child_view), &iter, x, y);