sugar-toolkit-gtk3/sugar/canvas/Timeline.py

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import gobject
class _Tag:
def __init__(self, name, start_frame, end_frame):
self.name = name
self.start_frame = start_frame
self.end_frame = end_frame
class TimelineObserver:
def __init__(self, observer):
self._observer = observer
def next_frame(self, tag, current_frame, n_frames):
try:
method = getattr(self._observer, 'do_' + tag)
method(current_frame, n_frames)
except:
pass
class Timeline:
def __init__(self, observer):
self._fps = 12
self._tags = []
self._name_to_tag = {}
self._current_frame = 0
self._timeout_sid = 0
self._observer = TimelineObserver(observer)
def add_tag(self, name, start_frame, end_frame):
tag = _Tag(name, start_frame, end_frame)
self._tags.append(tag)
self._name_to_tag[name] = tag
def remove_tag(self, name):
tag = self._tags[name]
self._tags.remove(tag)
del self._tags[name]
def _next_frame(self, tag, frame):
n_frames = tag.start_frame - tag.end_frame
self._observer.next_frame(tag.name, frame, n_frames)
def goto(self, tag_name, end_frame=False):
self.pause()
tag = self._name_to_tag[tag_name]
if end_frame:
self._current_frame = tag.end_frame
else:
self._current_frame = tag.start_frame
self._next_frame(tag, self._current_frame)
def on_tag(self, name):
tag = self._name_to_tag[name]
return (tag.start_frame <= self._current_frame and \
tag.end_frame >= self._current_frame)
def _get_tags_for_frame(self, frame):
result = []
for tag in self._tags:
if tag.start_frame <= frame and tag.end_frame >= frame:
result.append(tag)
return result
def _timeout_cb(self, end_frame):
for tag in self._get_tags_for_frame(self._current_frame):
cur_frame = self._current_frame - tag.start_frame
self._next_frame(tag, cur_frame)
if self._current_frame < end_frame:
self._current_frame += 1
return True
else:
return False
def play(self, start_tag=None, stop_tag=None):
self.pause()
if start_tag == None:
start = 0
else:
start = self._name_to_tag[start_tag].start_frame
if stop_tag == None:
end = self._tags[len(self._tags) - 1].end_frame
else:
end = self._name_to_tag[stop_tag].end_frame
self._current_frame = start
interval = 1000 / self._fps
self._timeout_sid = gobject.timeout_add(
interval, self._timeout_cb, end)
def pause(self):
if self._timeout_sid > 0:
gobject.source_remove(self._timeout_sid)