def _prepare_frames(self):
if self._frames_prepared:
return
tl = TrackLibrary()
# TODO: We might want to do some cleverer sorting
print("Sorting tracks by time...")
tracks = [t for t in tl.sort_tracks_by_time() if t in self.tracks]
print("Sorted")
self.frames = []
if self.timelapse_unit == "track":
batchsize = self.units_per_frame
# This splits a list into batches, ie
# [1,2,3,4,5] -> [[1,2],[3,4],[5]]
cumulative_tracks = []
counter = 0
print("Creating frames")
startnums = xrange(0, len(tracks), batchsize)
# The end number should be 1 more than might be expected,
# because of the way python list slicing works
batches = [(s, s + batchsize) for s in startnums]
total = len(batches)
for tracklist in (tracks[s:e] for (s, e) in batches):
counter += 1
if counter % 100 == 0 and total > 200:
print("\tCreated %s/%s frames" % (counter, total))
cumulative_tracks.extend(tracklist)
canvas = self._get_canvas(counter - 1)
self.frames.append(Frame(canvas=canvas,
tracks=deepcopy(cumulative_tracks),
frame_number=counter-1))
else:
raise NotImplementedError("Don't know how to handle %s" %
self.timelapse_unit)
self._frames_prepared = True
