Re: The simplest way to fade out a view
Re: The simplest way to fade out a view
- Subject: Re: The simplest way to fade out a view
- From: Nick <email@hidden>
- Date: Fri, 20 May 2011 23:21:38 +0300
Chase,
thank you for your responses.
I actually tested both your code and the code of Gustavo. For me the result
was the same - the opacity changes back to 1.0 when the animation had
finished and then i hide it, which still causes blinking...
Before the animation starts, i need to set the opacity to 1.0 for your code
- the "animator" uses it as starting value (and the final value is specified
by the line alphaAnimation.toValue = [NSNumber numberWithFloat:0.0];).
So, since in the Layer Tree the opacity is 1.0, after the animation
finishes, the view becomes opaque again.
The only thing that worked for me was [[[myView] animator]
setAlphaValue:0.0], which did not end up with the opacity 1.0 after
animation had finished, but i need to use a timer to hide the view. I only
was thinking there would be a "simpler" solution.
Well, i guess i made up a big problem from a little desire to make my
application to look more "alive" to the user :-)
Here is a full code that ends up with the opacity 1.0 (instead of 0.0 as i
needed to have)
CABasicAnimation * alphaAnimation = [CABasicAnimation animationWithKeyPath:
@"opacity"];
alphaAnimation.delegate = self;
alphaAnimation.removedOnCompletion = YES;
alphaAnimation.autoreverses = NO;
alphaAnimation.timingFunction = [CAMediaTimingFunction functionWithName:
kCAMediaTimingFunctionEaseInEaseOut];
alphaAnimation.duration = 1.0f;
alphaAnimation.toValue = [NSNumber numberWithFloat:0.0];
[[theView layer] setOpacity:1.0];
[[theView layer] addAnimation:alphaAnimation forKey:@"opacity"];
2011/5/20 Chase Latta <email@hidden>
> Did you try making that change in your code? If yes, is your view layer
> backed?
>
> I work mainly on iOS so I could be missing something but the code worked
> without blinking for me on 10.6.
>
> What is happening, as I think I understand it, is that by setting the
> opacity of your view's layer to 0.0 you trigger the implicit animation for
> opacity. But if you add an animation for the opacity key path that animation
> will be used. What you are doing is simply adding an animation. When it
> finishes it jumps back to the original value before you hide it. You need to
> set the opacity of your layer to zero at some point in your code. The
> animation that you see is actually the animation of the presentationLayer.
>
> I could be wrong on how all this works but my quick test does not cause the
> view to blink.
>
> Chase
>
>
> On May 20, 2011, at 12:26 PM, Nick <email@hidden> wrote:
>
> Chase,
> the animation itself worked and works - either with your code or with
> Gustavo's.
>
> But after the animation finishes, the opaqueness of the view again becomes
> 1.0 again. Then the "animationDidStop" gets called and the view disappears.
> But before disappearing, it annoyingly blinks (so, the opaqueness changes
> like this: 1.0, 0.9, 0.8, ..., 0.1, *1.0*, hidden).
>
> I am wondering *how could i make it save the final state of the animation* -
> to remain transparent when the "animationDidStop" callback gets called -
> which will allow the view not to blink.
>
> I understand (i hope i do :-) ) that i am actually changing the opaqueness
> of the layer (i.e., of the temporary graphical representation) and not of
> the view itself, but maybe i could get rid of blinking somehow.
> Thank you!
>
> 2011/5/20 Chase Latta < <email@hidden>email@hidden>:
> >> How could i force the animation to actually change the alpha value
> >> from 1.0 to 0.0 and make it stay 0.0 unless i change it back?
> >
> > Change your code to look like this:
> >
> > CABasicAnimation * alphaAnimation = ...
> > ...
> > [[theView layer] setOpacity:0.0]; // Set your opacity here
> > [[theView layer] addAnimation:alphaAnimation forKey:@"opacity"];
> > // Note the key
> > }
> >
> > By setting the key to @"opacity" instead of @"opacityAnimation" your
> > animation will used instead of the default animation when you call
> > [CALayer setOpacity:].
> >
> > There is a good WWDC talk about animation on the ipad that addresses
> > this. I don't remember the exact talk, though.
> >
> > Chase
> >
>
>
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