Hi,
I'm trying to make the footer of a Frame display different widgets when it
receives an alarm. I'd prefer to put this logic in the footer widget itself
rather than using Frame.set_footer to keep the frame code simple (although
maybe
this should be reconsidered).
The way I've done this, the footer may fail to render the changes depending on
the body widget. I can't figure out why, but I suspect something to do with
canvas caching.
I've discovered that subclassing WidgetWrap instead of hacking my own wrapper
fixes it (so I'll use that instead), but I want to understand how my first try
failed so I can avoid it in the future. Any insight to this would be greatly
appreciated.
-- Jacob
#!/usr/bin/env python2
from urwid import (Frame, SimpleListWalker, PollingListWalker, ListBox, Text,
MainLoop)
class ToggleFrame(Frame):
"""Press 'tab' to switch bodies."""
def __init__(self):
self.body1 = ListBox(SimpleListWalker((Text('Fails to redraw'),)))
self.body2 = ListBox(PollingListWalker((Text('Expected behavior'),)))
# Same as: self.body2 = ListBox((Text('Expected behavior'),))
self.footer = Footer()
super(ToggleFrame, self).__init__(self.body1, footer=self.footer)
def keypress(self, size, key):
if key == 'tab':
if self.get_body() is self.body1:
self.set_body(self.body2)
elif self.get_body() is self.body2:
self.set_body(self.body1)
else:
return key
class Footer(object):
"""Masquerade as another widget, switching on an alarm."""
def __init__(self):
self.one = Text('one')
self.two = Text('two')
self.current = self.one
def switch(self, loop, *args):
if self.current is self.one:
self.current = self.two
elif self.current is self.two:
self.current = self.one
#loop.draw_screen() # Doesn't make any difference
loop.set_alarm_in(0.5, self.switch)
def __getattr__(self, attr):
"""We would normally use WidgetWrap for this kind of thing."""
return getattr(self.current, attr)
frame = ToggleFrame()
loop = MainLoop(frame)
loop.set_alarm_in(0.5, frame.footer.switch) # Footer toggles itself after this.
loop.run()
# EOF
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