Re : Re: NSTextField

[David Ayers]

Hi Stefan,

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2002 Jun 28 - 13:25
Stefan Böhringer <stefan.boehringer+usenet@uni-bochum.de> 
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>I see your problem now. The question is what triggers the
>setNeedsDisplay:YES call which in turn causes the flickering. Is it the
>drawing of the selection?

Yes, this triggers the setNeedsDisplay, and it's OK that it does so.

> Perhaps a delayedPerform: could help to
>postpone the redrawing. Then again I do not know about the point in time
>when delayedPerform: methods are executed.
>Another question is what is flickering after all. If it is the whole
>window this indicates that redrawing is too extensive and should perhaps
>be optimized in the first place.

It's not real flickering. If you click inside a TextField (with contents) it 
will select the entire content shortly and then reinsert the insertion point at 
the location of the click. (or show the actual selection if you dragged-clicked)

I still couldn't test it on openstep, yet I found some documatation that makes 
me beleive that the flushWindow approach is the correct way to do this. As I 
said, only NSBackingStorNonretained is still causing this effect with the 
enable/disableflushWindow approach but the online Docs from Apple

http://developer.apple.com/techpubs/macosx/Cocoa/TasksAndConcepts/ProgrammingTopics/WinPanel/index.html

also mention:
"Both retained and nonretained windows are also subject to a flashing effect as 
individual drawing operations are performed, but their results do get to the 
screen more quickly than those of buffered windows."

So my guess it, something similar will happen.

Dave

PS: Thanks again Richard for the tip on exception handler to ensure flushing 
will be reenabled. And I also think the _handleWindowNeedsDisplay: should 
reschedule itself in case isFlushWindowDisabled returns YES and just return. 
I'll try to get the modifications together soon.