[PiTiVi] Progress Report

[Brandon Lewis <brandon_lewis berkeley edu>]

With things having calmed down somewhat,  I spent the better part of 
last week familiarizing myself with both pygtk and the PiTiVi source. I 
wrote a simple pygtk utility as well -- a settings dialog for matchbox 
desktop -- in order to help get myself back into the groove of coding 
with python and gtk.

Earlier this week, Edward Hervey and I agreed on on a simple task for 
the PiTiVi video editor. To understand it, first examine this UI mockup:
http://www.pitivi.org/images/8/88/Deroule-addscene2.png

This UI mockup shows the gtk.SimpleSourceWidget, which represents a 
movie clip in the PiTiVi timeline. It features a thumbnail, destroy box, 
edit button, effects thumbnail and volume control slider. The current 
code only implements the thumbnail, which is directly painted into the 
widget's drawing area. My task was to add a destroy box, and connect it 
to the appropriate signal handler. This proved to be challenging because 
SimpleSourceWidget is derived from gtk.DrawingArea, which is not a 
container. Rather than re-inventing the wheel and writing my own event 
handling code, I solved this problem by completely re-implementing the 
widget as a subclass of gtk.EventBox, which is a container widget. 
gtk.EventBox also allows me to set the background color of the 
SimpleSourceWidget, a crucial feature. The downside to this approach is 
that the thumbail for the clip needs to be a widget itself, and the 
gtk.Image widget does not scale the video. I decided to create a new 
widget, ScaledThumbnailViewer which displays a scaled thumbnail at the 
appropriate aspect ratio. This is advantageous because it makes adding 
the second effects preview thumbnail very easy. I suspect I will find 
many uses for this thumbnail viewer class.

I continued laying out the rest of the widgets components. I also had to 
correct some issues relating to the way the container timeline widget 
sized the components, but this was pretty straight forward in the end.

here's a screenshot: 
http://www.ocf.berkeley.edu/~brandon/pitivi/SimpleFileSource.png
as you can see, there's room for some cosmetic tweaks, but all the 
elements are in place.