[gnome-builder/wip/minimap2] minimap: allow scrubbing with button-press/drag on scrubber

[Christian Hergert <chergert src gnome org>]

commit bff1d0d98a5ca0f291427ec91f5cf7f2b331427f
Author: Christian Hergert <christian hergert me>
Date:   Tue Apr 21 15:46:44 2015 -0700

    minimap: allow scrubbing with button-press/drag on scrubber
    
    This allows you to quickly jump around in the visible area. We need to
    spend some time thinking about a couple of things going forward.
    
     1) a11y - not sure what we can do here for that.
     2) theming - where should the highlight overlay color come from.
                   gtksourcestylescheme or css come to mind.

 libide/ide-source-map.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 42 insertions(+), 0 deletions(-)
---
diff --git a/libide/ide-source-map.c b/libide/ide-source-map.c
index 5bc5c27..da85132 100644
--- a/libide/ide-source-map.c
+++ b/libide/ide-source-map.c
@@ -37,6 +37,8 @@ struct _IdeSourceMap
   GtkSourceView        *child_view;
   GtkEventBox          *overlay_box;
   GtkSourceView        *view;
+
+  guint                 in_press : 1;
 };
 
 struct _IdeSourceMapClass
@@ -436,6 +438,10 @@ ide_source_map__overlay_box_button_press_event (IdeSourceMap   *self,
   g_assert (event != NULL);
   g_assert (GTK_IS_EVENT_BOX (overlay_box));
 
+  gtk_grab_add (GTK_WIDGET (overlay_box));
+
+  self->in_press = TRUE;
+
   return GDK_EVENT_PROPAGATE;
 }
 
@@ -448,6 +454,10 @@ ide_source_map__overlay_box_button_release_event (IdeSourceMap   *self,
   g_assert (event != NULL);
   g_assert (GTK_IS_EVENT_BOX (overlay_box));
 
+  self->in_press = FALSE;
+
+  gtk_grab_remove (GTK_WIDGET (overlay_box));
+
   return GDK_EVENT_PROPAGATE;
 }
 
@@ -460,6 +470,38 @@ ide_source_map__overlay_box_motion_notify_event (IdeSourceMap   *self,
   g_assert (event != NULL);
   g_assert (GTK_IS_EVENT_BOX (overlay_box));
 
+  if (self->in_press && (self->view != NULL))
+    {
+      GtkAllocation alloc;
+      GtkAllocation child_alloc;
+      GtkTextBuffer *buffer;
+      GdkRectangle rect;
+      GtkTextIter iter;
+      gdouble ratio;
+      gint x;
+      gint y;
+
+      gtk_widget_get_allocation (GTK_WIDGET (overlay_box), &alloc);
+      gtk_widget_get_allocation (GTK_WIDGET (self->child_view), &child_alloc);
+
+      gtk_widget_translate_coordinates (GTK_WIDGET (overlay_box),
+                                        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);
+
+      y = (rect.y + rect.height) * ratio;
+
+      gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (self->child_view), &iter, x, y);
+
+      gtk_text_view_scroll_to_iter (GTK_TEXT_VIEW (self->view), &iter, 0.0, TRUE, 1.0, 0.5);
+    }
+
   return GDK_EVENT_PROPAGATE;
 }