[pitivi] trackobject: stabilize layer height calculation

[Edward Hervey <edwardrv src gnome org>]

commit 65f3ecab684d07a4a00d00c26c17638bdbfe5fcb
Author: Brandon Lewis <brandon_lewis berkeley edu>
Date:   Sun Mar 15 14:34:27 2009 -0700

    trackobject: stabilize layer height calculation
---
 pitivi/ui/controller.py  |    3 +++
 pitivi/ui/trackobject.py |    7 +++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/pitivi/ui/controller.py b/pitivi/ui/controller.py
index f29413e..29108ac 100644
--- a/pitivi/ui/controller.py
+++ b/pitivi/ui/controller.py
@@ -59,6 +59,9 @@ class Controller(object):
         return Point(*self._canvas.convert_from_item_space(item,
             *self.from_event(event)))
 
+    def to_item_space(self, item, point):
+        return Point(*self._canvas.convert_to_item_space(item, *point))
+
     def pos(self, item):
         bounds = item.get_bounds()
         return Point(bounds.x1, bounds.y1)
diff --git a/pitivi/ui/trackobject.py b/pitivi/ui/trackobject.py
index 7f530ac..47ed9f6 100644
--- a/pitivi/ui/trackobject.py
+++ b/pitivi/ui/trackobject.py
@@ -15,6 +15,7 @@ from preview import Preview
 import gst
 from common import LAYER_HEIGHT_EXPANDED, LAYER_HEIGHT_COLLAPSED
 from common import LAYER_SPACING
+from pitivi.ui.point import Point
 
 LEFT_SIDE = gtk.gdk.Cursor(gtk.gdk.LEFT_SIDE)
 RIGHT_SIDE = gtk.gdk.Cursor(gtk.gdk.RIGHT_SIDE)
@@ -107,6 +108,8 @@ class TrackObject(View, goocanvas.Group, Zoomable):
         def drag_start(self):
             TimelineController.drag_start(self)
             self._view.raise_(None)
+            tx = self._view.props.parent.get_transform()
+            self._y_offset = tx[5]
 
         def click(self, pos):
             mode = 0
@@ -121,8 +124,8 @@ class TrackObject(View, goocanvas.Group, Zoomable):
             x, y = pos
             self._view.element.setStart(max(self._view.pixelToNs(x), 0),
                     snap=True)
-            priority = int(max(0, 1 + (y // (LAYER_HEIGHT_EXPANDED +
-                LAYER_SPACING))))
+            priority = int(max(0, (y - self._y_offset) // (LAYER_HEIGHT_EXPANDED +
+                LAYER_SPACING)))
             self._view.element.priority = priority
 
     def __init__(self, element, track, timeline):