Re: drawRect troubles
Re: drawRect troubles
- Subject: Re: drawRect troubles
- From: Ivan Kourtev <email@hidden>
- Date: Sat, 28 Oct 2006 23:33:36 -0400
On Oct 28, 2006, at 11:11 PM, Scott Stevenson wrote:
On Oct 28, 2006, at 8:05 PM, Ivan Kourtev wrote:
For performance reasons I am trying to do incremental drawing --
draw/erase only small amounts of stuff that has changed -- but it
seems that the view contents is "erased" between successive calls
to drawRect. After each drawRect, I only see the incremental
drawing -- the small stuff added/removed -- but not what was there
before.
Have you tried playing with Quartz Debug's "flash updates" checkbox?
Should show you which areas are considered invalid at which points.
Might help.
- Scott
Yes, I've been doing this. All the update areas seem to be correct.
The problem is that the drawing I see in the view contains only what
was done explicitly in drawRect.
I was under the impression that what's been drawn in the view so far
is there, and if I don't want it, I have to erase it. So I am only
adding small pieces of stuff in drawRect -- and they do appear on
screen. All of the previous drawing is gone.
Since I am issuing the [self setNeedsDisplay:YES] is there any way to
also specify which particular parts of the view should be
invalidated? Right now, the argument to drawRect is always the
entire view area.
-- ivan
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