Randy Smith wrote:
The cropping and scrolling works fine. But when I try to add
responding to resize events, I get into trouble. Specifically:
* When I naively change the size of the image shown to be borderwidth
less than the size indicated in the configure event, the size of the
image shown grows gradually but inexorably when I start the test
app. (Sorta scary, actually :-})
* When I fiddle a bit to figure out what the actual difference in size
is between the Configure event and the image that can be displayed,
I get a vibrating, jagged display of the image.
Investigation suggests that multiple configure events are hitting the
label in response to each user resize with different sizes. I'm
guessing that when I resize the image in response to those different
events, that creates new resize events propagating through the window
manager hierarchy, which creates new configure events, which means my
handler changes the image size, which ... you get the idea.
I can't test your code because I don't have the test image and for some
reason it does not recognize a tiff of my own. But, just glancing at
your code, it looks like a quick-fix would be to set self.zoom to a
sentinel at the end of refresh() and return 'break' at the top of the
methods that use self.zoom if it is said sentinel value (e.g. "if
self.zoom == WHATEVER_SENTINEL: return 'break'). You may also want to
return 'break' for event responders that should terminate the event
chain. This is a general technique to stop a lot of unwanted event
propagation.
James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com
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