I really think you ought to try what I said. I just did and I'm not seeing any
flash. Here's my code:
- (IBAction) doButton: (id) sender { // toggle view size
CGRect f = self->mmview.frame;
if (f.size.height == 200) {
f.size.height = f.size.width = 100;
self->mmview.frame = f;
return;
}
if (f.size.height == 100) {
f.size.height = f.size.width = 200;
self->mmview.frame = f;
return;
}
}
And here's the code for the view subclass:
- (void) awakeFromNib {
[super awakeFromNib];
CALayer* lay = [CALayer layer];
lay.frame = self.layer.bounds;
[self.layer addSublayer: lay];
lay.contents = (id)[[UIImage imageNamed:@"manny.jpg"] CGImage];
self.which = @"manny";
}
- (void) layoutSublayersOfLayer: (CALayer*) layer {
[CATransaction setDisableActions:YES]; // looks fine without this, too
for (CALayer* lay in layer.sublayers) {
lay.frame = layer.bounds;
if (lay.contents) {
if ([self.which isEqualToString:@"manny"]) {
lay.contents = (id)[[UIImage imageNamed:@"moe.jpg"] CGImage];
self.which = @"moe";
}
else if ([self.which isEqualToString:@"moe"]) {
lay.contents = (id)[[UIImage imageNamed:@"manny.jpg"] CGImage];
self.which = @"manny";
}
}
}
}
So it seems to me I'm doing exactly what you said; when the view changes frame,
I'm changing the sublayer frame to match, plus I'm changing the sublayer
contents. And there's no flash.
m.
On Wed, 2 Feb 2011 18:29:48 +0800, Roland King <r...@rols.org> said:
>
>On 02-Feb-2011, at 1:38 AM, David Duncan wrote:
>
>> On Feb 1, 2011, at 4:32 AM, Roland King wrote:
>>
>>> I have a UIView subclass in my iOS app and the content for that UIView is 3
>>> CALayers, each with a bitmap image for their content, added as sublayers of
>>> the UIView's layer. Each of the CALayers is the full size of the UIView's
>>> layer (they have transparency to composite them together).
>>>
>>> When the UIView is resized the setFrame: method is called and I have a
>>> custom implementation of that which sets the bounds of the sublayers so
>>> they again fill the UIView's layer, and draws a new bitmap for each of them
>>> of the right size and sets it into their contents.
>>>
>>> However, when I resize, there's a brief flash of the current content,
>>> before it's been redrawn, stretched to fill the new sized window, before
>>> the new content replaces it. Nothing I've tried has been able to stop that
>>> brief flash and I can't figure out where it's coming from.
>>
>>
>> I suppose my first question is why not just use UIViews instead? They should
>> already abstract all of what you need to make this work away from you, and
>> you should only need to set the view's contentMode property to
>> UIViewContentModeRedraw to get the behavior you seem to desire. Then it
>> would just be a matter of teaching the UIViews how to draw themselves to
>> generate their own content instead of having the parent UIView do so and
>> push it to them.
>>
>> As for overall, I'm not entirely certain what is happening, but it sounds
>> like you have a timing issue, possibly one where the view's are resized on
>> one runloop invocation and their contents replaced on the next. Instead of
>> overriding -setFrame: you should override -layoutSubViews: which should
>> catch more cases where layout is needed and allow you to do the work you
>> need at the right time.
>> --
>> David Duncan
>>
>
>Yeah I ended up with layers because I started constructing one UIImage by
>drawing to a bitmap context and then split it up into three pieces (backdrop,
>bit in the middle and an overlay) so I didn't have to keep redrawing the bits
>that weren't changing and at that point I though layers instead of images, but
>I certainly try to pull myself up the tree a bit and move it back to UIViews.
>I'm just bothered that I can't figure this out, CALayers should work ok for
>this.
>
>-layoutSubViews: doesn't work for this either, I tried that already, and that
>does seem to ensure I end up with the calls on two different runloop
>invocations, which is worse.
>
>I tend to agree that it's a timing issue, but I can't find it, I'm explicitly
>doing everything in the one method, removing layers or removing their contents
>before they are resized etc, so the only thought I'm left with is that core
>animation is shifting the actual work to another thread, even when I've turned
>off actions and put things in CATransactions and whatever order I do things in
>makes little difference, that thread sees the net change and animates between
>it, doing the resize first.
>
>Thanks for the reply though, if I can't sort this out (and I have perhaps one
>more good idea) I'll try using UIImageViews instead.
>
>
>
>
--
matt neuburg, phd = m...@tidbits.com, <http://www.apeth.net/matt/>
A fool + a tool + an autorelease pool = cool!
AppleScript: the Definitive Guide - Second Edition!
http://www.apeth.net/matt/default.html#applescriptthings_______________________________________________
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