Preview unresponsive if certain images or titles are hidden

[txapelgorri]

Hi there:
 - Ubuntu 9.04 32bits
 - OpenShot 0.9.43
I just start a new project adding a title and two photos, add them to a track and I just switch off video on one photo (eye icon). Then the preview feature refuses to start.

Maybe this it's not a bug "as others", but I think this action (switch off video in one clip) should cause an alert (at least) to the user, telling about this lack of functionality.

[Jay S (topdownjimmy)]

I can reproduce this in any case where an image or title is hidden and is not the last item in its track. If a hidden image or title is followed later in its track by any other item, this error occurs. The preview refuses to play (or seek) without explanation; other than this, the program remains responsive, and does not crash (although it occasionally freezes for several seconds). Terminal gives this output:

on_tlbPlay_clicked called with self.tlbPlay
Traceback (most recent call last):
  File "/usr/share/openshot/windows/MainGTK.py", line 1212, in on_tlbPlay_clicked
    self.project.RefreshXML()
  File "/usr/share/openshot/classes/project.py", line 230, in RefreshXML
    self.GenerateXML(os.path.join(self.USER_DIR, "westley.xml"))
  File "/usr/share/openshot/classes/project.py", line 211, in GenerateXML
    self.sequences[0].GenerateXML(dom, tractor1)
  File "/usr/share/openshot/classes/sequences.py", line 205, in GenerateXML
    MyTrack.GenerateXML(dom, multitrack)
  File "/usr/share/openshot/classes/track.py", line 114, in GenerateXML
    current_frame = MyClip.GenerateXML(dom, playlist, current_frame)
  File "/usr/share/openshot/classes/clip.py", line 241, in GenerateXML
    blank = round(self.position_on_track * fps) - current_frame
TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'

[Jay S (topdownjimmy)]

"I can reproduce this in any case where an image or title is hidden and is not the last item in its track."

If the hidden image or title is the *only* item in its track, however, the error does not occur.

[Jonathan Thomas (jonoomph)]

This has been fixed and committed. I'll push it bzr later tonight.