Re: scrolling and drawing porblems
Re: scrolling and drawing porblems
- Subject: Re: scrolling and drawing porblems
- From: m <email@hidden>
- Date: Tue, 7 Nov 2006 13:11:12 -0800
Then you'll probably need to do something like let the scroll view
copy on scroll, then in your view's drawRect: method, draw "outside
the lines" of the rect you get as a peramter. Basically redraw where
your static stuff was before scrolling and where it should be after.
_murat
On Nov 7, 2006, at 12:52 PM, Ivan Kourtev wrote:
On Nov 7, 2006, at 3:43 PM, m wrote:
On Nov 7, 2006, at 12:25 PM, Ivan Kourtev wrote:
I want to have a certain object drawn at a constant position
relative to the visible rectangle of my custom view (so that it's
always visible). The problem was that the my custom view was in
a scroll view that by default copies view content on scroll. As
both you and Eric suggested one way to accomplish what I wanted
was to disable the copying. Indeed, something like [[self
enclosingScrollView] setCopiesOnScroll:NO]; in my custom view did
the job.
The side effect of this is that since there is no copying
anymore, the argument to drawRect in my custom view after
scrolling is the entire visible rectangle (rather than just a
small strip exposed after scrolling).
Is this a problem in fact or in theory? Put another way, are you
noticing (as a user) a performance impact as a result of having to
redraw the while view instead of just a bit? Depending on how
complex and expensive your drawing is, you might find the code
complexity required (time spent coding, fixing, maintaining) to
optimize drawing doesn't pay off in substantial user perceived
responsiveness.
I absolutely agree but in this particular case performance is
impacted significantly indeed.
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