Re: scrolling and drawing porblems
Re: scrolling and drawing porblems
- Subject: Re: scrolling and drawing porblems
- From: Ivan Kourtev <email@hidden>
- Date: Tue, 7 Nov 2006 10:15:01 -0500
I subclassed NSScrollView to try and draw under my custom view. But
I am seeing weird things.
First, I am not drawing any background in my custom view but still
don't see the drawing in the custom enclosing NSScrollView? Drawing
in the custom NSScrollView started showing after only I overrode
isOpaque of my custom view to return YES, which has me thoroughly
confused.
So if my custom view's isOpaque is not overridden at all, or if it
returns NO, the drawing in the enclosing custom NSScrollView does not
show. Isn't that exactly the opposite of what it should be?
On Nov 6, 2006, at 6:53 PM, Erik Buck wrote:
Here are a bunch of ideas in roughly decreasing order of sensibility:
1) Try turning off copies on scroll behavior:
setCopiesOnScroll: Controls whether the receiver copies rendered
images while scrolling.
- (void)setCopiesOnScroll:(BOOL)flag
Discussion If flag is YES, the receiver copies the existing
rendered image to its new location while scrolling and only draws
exposed portions of its document view. If flag is NO, the receiver
always forces its document view to draw itself on scrolling.
Availability
Available in Mac OS X v10.0 and later.
See Also
– copiesOnScroll
2) You can also send your view a -setNeedsDisplay: message and
the whole visible rect will be marked as needing redisplay.
3) You can also draw your immovable graphics as part of the clip
view or part of the enclosing scroll view instead of part of the
scrollview's document view. Think about the way the scrollview
draws rulers. You can do that too via overriding the -tile method.
4) You can also draw your immovable graphics in a transparent
child window overlaying the scroll view.
5) You could use a subview of your scrollview's document view to
draw the immovable graphics. Then whenever the document view's
visible rect changes, reposition the subview which will cause a
redraw when appropriate.
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