Paul Chapman paul at igblan.free-online.co.uk
Mon Apr 28 15:53:42 UTC 2003

I'm starting to find out where the code hooks into Morphic are.  I found #fullDrawOn:, which looks like the place to put my drawing code for a pane.  But I have a few simple questions.

(1) Is this the only drawing hook?  What's #drawOn: for?

(2) The canvas argument my pane is passed does not seem to be clipped to the pane.  This surprised me.  Is this the right behaviour?  Am I supposed to do my own clipping using something like #clipBy:during: ?

(3) I noticed that when my window is first creatd and displayed, #fullDrawOn: is called three times.  This seems excessive. :)  I'm used to battling the Windows API to stop unnecessary extra WM_PAINT messages.  Am I up against the same kind of thing in Squeak?

(4) Squeak seems to have problems coping with errors during the execution of #fullDrawOn: -  I get a stack dump to the screen instead of a debugger, and the image usually dies.  This makes code here hard to debug.  Is there a general approach to debugging drawing code to work around this?

Thanks for any help anyone can give. :)

Cheers, Paul

More information about the Squeak-dev mailing list