[pitivi: 2/3] zoominterface.py: clamp ratio to minimum of 0 in computeZoomLevel()

[Edward Hervey <edwardrv src gnome org>]

commit 5a72e5bd97a7fffcd7e8a8da037deadc2ee46e35
Author: Brandon Lewis <brandon_lewis alum berkeley edu>
Date:   Tue Apr 20 16:28:40 2010 -0700

    zoominterface.py: clamp ratio to minimum of 0 in computeZoomLevel()
    
    closes launchpad bug 549384

 pitivi/ui/zoominterface.py |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/ui/zoominterface.py b/pitivi/ui/zoominterface.py
index 4456715..0471855 100644
--- a/pitivi/ui/zoominterface.py
+++ b/pitivi/ui/zoominterface.py
@@ -109,8 +109,10 @@ class Zoomable(object):
 
     @classmethod
     def computeZoomLevel(cls, ratio):
-        return int((((ratio - cls.min_zoom) / cls.zoom_range) ** (1.0/3.0)) *
-            cls.zoom_steps)
+        return int((
+            (max(0, ratio - cls.min_zoom) /
+                cls.zoom_range) ** (1.0/3.0)) *
+                    cls.zoom_steps)
 
     @classmethod
     def pixelToNs(cls, pixel):