Re: NSAnimatablePropertyContainer

FROM : Troy Stephens
DATE : Fri Nov 16 18:42:33 2007

Change your setImageAlpha:0.0 to message the view directly:

    [myCustomView setImageAlpha:0.0];

That will set up the initial value, from which you'll then animate to 
1.0.

The way the code is written now, [[myCustomView animator] 
setImageAlpha:0.0] queues up an animation from the present value to 
0.0 (which won't begin executing until control returns to the 
runloop).  Then [[myCustomView animator] setImageAlpha:1.0] schedules 
another animation to 1.0 that supersedes the animation to 0.0.  Almost 
certainly the reason that changes to "imageToDisplay" after the first 
fail to animate is that imageAlpha is already 1.0, so the animation to 
1.0, the one that replaces the animation to 0.0, has nothing to do.

On Nov 15, 2007, at 7:22 PM, I. Savant wrote:

> List:
>
>  I'm finally playing around with Core Animation. I have a view which 
> (for simplicity sake) has two properties:
>
> NSImage * imageToDisplay  (default nil)
> CGFloat imageAlpha    (default 0.0)
>
>  I have the +defaultAnimationForKey: working fine. It dutifully 
> returns a well-formed CABasicAnimation per the example in the 
> NSAnimatablePropertyContainer protocol reference documentation.
>
>  I want to do something like this:
>
> - (void)someMethodWithSomeImage:(NSImage *)image
> {
>    [[myCustomView animator] setImageAlpha:0.0];
>    [myCustomView setImageToDisplay:image];
>    [[myCustomView animator] setImageAlpha:1.0];
> }
>
>  When imageToDisplay is first set, the new image fades in from the 
> default 0.0 beautifully. Subsequent sets fail to animate (they go 
> straight to the new image). I *assume* this is because the animation 
> is non-blocking and by the time the first interpolated alpha value 
> gets set (and drawn) the custom view's imageToDisplay is already 
> something else.
>
>  I spent quite some time tonight trying to figure out how to set the 
> 'blocking mode' as NSAnimation allows ( [someNSAnimation 
> setAnimationBlockingMode:NSAnimationBlocking] ) but CAAnimation, 
> CABasicAnimation, etc. don't seem to allow this.
>
>  Am I missing something or is it not possible to have a blocking 
> animation in this way?
>
> --
> I.S.
>
>
>
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