Re: NSTextField

[Stefan Böhringer]

To compare implementations you should better look at MacOSX rather than
Openstep since Openstep makes use of a special display postscript
operator called highlight (IIRC). This is quite of a hack since it
replaces pixels in the framebuffer of one color with another one (say
replace white pixels with gray ones). This is a implementation running
quickly but not well portable.
Why is there both, a selectText: and a mouseDown: method sent? From a
glance I cannot reproduce your described behaviour (say in GWorkspace).

Best wishes,

        Stefan

On Fri, 2002-06-28 at 13:44, David Ayers wrote:
> Hi Stefan,
> 
> --------------------------------------------------------------------------
> 2002 Jun 28 - 13:25
> Stefan Böhringer <stefan.boehringer+usenet@uni-bochum.de> 
> --------------------------------------------------------------------------
> >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.