I'd like help on some strategies to sequence some animations.
I subclassed UIImageView so that I could write some custom animation actions on an image. I implemented a few methods to be used as actions that I could call on my image
example:
-(void)rotateAnim; //rotates the image by a few degrees using a CGAffine Transform
-(void)numbersFlashAnim; //uses the UIImageVew.animationImages array for a 14 frame animation.
-(void)moveLeftAnim; //uses another CGAffine Transform to change the imageView's position.
In my viewDidLoad method I create an instance of my UIImageView subclass. What ways exist to call these animations in sequence?
I was thinking about using an NSTimer to handle the animations, but wasn't sure if you could write an NSTimer object to handle multiple method calls.
example:
[imageView rotateAnim]; //when this animation is done, I want to call:
[imageView numbersFlashAnim];
I've seen several questions regarding the use of an NSTimer, but none that specifically relate to this problem. Note: I saw that the dev docs on apple's site also recommend the use of the performSelector:withObject:afterDelay: in some cases but was wondering if that would offer enough flexibility.
Additionally, I've already taken a look at the Cocos2d framework, and although I can use their methods ~(Sequence actions: etc, ) I'm choosing to solve this problem with UIKit/Foundation, etc.
Do you use animation? I mean you can rotate your image inside
[UIView beginAnimations:(NSString *)animationID context:(void *)context] block. There you can add a delegate method that will be called after current animation ends. And there you can call your numbersFlashAnim.
(Sorry for my english ;-) )
Related
I've created an UIView and some layers. I've organized those layers into superview-subview hierarchy with the root in UIView's layer, added some gesture recognizers and I am trying to manipulate layers' geometry on events from gesture recognizers (setting bounds and position for sure). I use implicit animations and CATransactions. No explicit animations are used.
The actual result is good enough if I create CATransaction with duration = 0. But if I set the duration to 0.2 I get some strange results: as event come not rapidly and previous transaction have time to be completed before the next starts everything is OK (for example on tapping), but if there is not enough time (for example on pinch or pan) the layer being resized starts jerking. Visually it looks like animation rolls back to the initial point and starts again to the new value.
I do not see any reason for this. I've tried to perform the layout in -[UIView layoutSubviews] and invoke setNeedsDisplay in gesture recognizers handlers. I've also tried to separate this logic into separate method but it does not help.
I repeat once more that I use only implicit animations. And what I want to know is why does it happen (but not how to work around).
Any clues?
I think, it's because you start new animation when previous not finished.
Maybe, you need to stop it like
[yourView.layer removeAnimationForKey:#"yourAnimationKey"];
and you need to implement animation delegate method
-(void)stopAnimation:(id)sender
{
yourView.frame = [[yourView.layer presentationLayer] frame]; // that set frame of your view to it's animation position
}
I have a CALayer and I would like to use it as an UIImageView. That way I'll be able to move it with timers etc... so here the layer :
CALayer *rootLayer = [CALayer layer];
And I would like to move it with timer like that :
Image.center=CGPointMake(Image.center.x +10, Image.center.y );
For this you'll need a CABasicAnimation. For the timer, create an NSTimer. Make sure that the timer fires the method on the main thread using one of the performSelectorOnMainThread methods.
That method will add the CABasicAnimation to the layer. You'll have to be careful with the end positions as when the animation finishes, your layer will still be visible in it's original position.
To resolve that you'll need to update the model value of the layer in the animationDidStart delegate callback of the CABasicAnimation.
Note that if it's a repeating animation - which I guess it is given you're using a timer - you can use the removedOnCompletion flag. That means you can re-use the same animation repeatedly. Check out this question for details on how to make use of that:
How to reuse an CABasicAnimation when not removed after completion?
I have a UIView with a bunch of subviews, all positioned using layoutSubviews. When the view is resized, the relative positions all change. I'd like these re-calculations to happen during an animated resize (using +[UIView beginAnimations:] calls). This doesn't seem to be happening. Any ideas?
Assumption: You want to have multiple animation steps (i.e. position doesn't change linearly with frame size).
This isn't possible with a single "standard" UIView animations. Why? The frame/bounds is only set once.
Core Animation has three "layer trees":
The model tree is where your app thinks things are.
The presentation tree is approximately what's being displayed on screen.
The render tree is approximately what Core Animation is compositing.
UIView is a (somewhat thin) wrapper around the model layer. During a UIView animation, Core Animation updates the presentation/render tree — the model tree represents the endpoint of animations. The upshot is that your code can (for the most part) treat animations as instantaneous — moving a view from A to B instantly moves it to B; the change just happens to be animated to the user.
There are more complicated things you can do with CALayer/CAAnimation directly, but I haven't investigated this much.
You could chain multiple animations together using -[UIView setAnimationDidStopSelector:]. (You could also try using multiple animations together with setAnimationDelay:, but I'm not sure what happens with multiple animations on the same property; you might have luck with setAnimationBeginsFromCurrentState:.)
If you want really fine-grained control, CADisplayLink (OS 3.1+) is a timer that fires after each screen refresh. A fallback option (for 3.0 support) is to use an NSTimer at 30/60 Hz or so.
I know this is an old question, but this code works for me very well (suited for your example of changing frame).
-(void)layoutSubviews{
[super layoutSubviews];
// layout your subviews here, or whatever
}
-(void)someMethod{
double duration=...;
[UIView animateWithDuration:duration animations:^{
self.frame = ...;
[self layoutIfNeeded];
}];
}
Of course you can call this method from another object. The "trick" is to call layoutIfNeeded (or layoutSubviews directly - same thing, if You change the frame the setNeedsLayout is called).
As tc. nicely explained the "layer trees", You just force the presentation layer to display the final stage of model layer with animation.
The advantage of this method is in possibility to control when the frame/bounds change is animated and when it's instant.
Hope this helps someone:).
Completing #GrizzlyNetch's anwer, you can set the UIViewAnimationOptionLayoutSubviews animation option, so you don't need to call layoutIfNeeded:
-(void)someMethod{
double duration = ...;
[UIView animateWithDuration:duration delay:0 options:UIViewAnimationOptionLayoutSubviews animations:^{
self.frame = ...;
} completion:nil];
}
Posting for completeness. Thanks to tc. for explaining that what I want to do, exactly, is not supported by Core Animation.
I eventually came up with a reasonable solution. Rather then layout my subviews in -layoutSubviews, I do so in -setBounds:. Then, when I wrap a -setBounds: call in a UIView +beginAnimations: block, those positioning calls are also animated, and the end result is everything properly animating to where it should god.
So I came from a Flash background where I can animate in timeline. I've completed the Beginning iPhone Development book and just realized that I still don't know how to get an animation in. I'm guessing I need to import png sequences?
Can anyone point me to an appropriate place to learn more about this topic? I want to make a game and my game objects need to animate.
Thanks in advance!!
The simplest type of animation, moving things around and fading in and out, can be done with a few static methods of UIVIew. You can affect the center, bounds, transform matrix and alpha level of one or more views.
[UIView beginAnimations:nil context:nil];
[fadingOutView setAlpha:0.0];
[slidingView setCenter:CGPointZero];
[shrinkingView setFrame:CGRectZero];
[fadingInView setAlpha:1.0];
[spinningView setTransform:CGAffineTransformMakeRotation( M_PI )];
[UIView commitAnimations];
Animations start with the current state of the view and interpolate to the state assigned between begin and commit animation. So if fadingInView already had an alpha of 1.0 (the default) there would be no change.
If you are unfamiliar with static methods [UIView method]; means call method on the class not an instance.
Using other UIView static methods you can control several details of the animation. Every UIView has a CALayer that also has a few properties that can be animated, the most interesting of which is the 3D transform property.
If the basic animation is not sufficient for you needs, you can either look into CAAnimation and related classes, or look to a third party animation library.
I think the best place to start learning is in your code, since you are just transitioning from Flash. Look at the very bottom of UIView.h to see the animation methods. Make a few views and move them around.
Take a look at cocos2d for iPhone. It has a good framework for handling sprites, animation (frame based and motion) as well as a lot of other stuff.
http://www.cocos2d-iphone.org
You can of course do all off this on your own with core graphics and core animation, but an API like cocos2d takes care of a lot of the nitty gritty details for you.
The Beginning iPhone Development book does not talk much about animation. You may read more about animation from Apple documentation, and play with some samples from Apple, such as the Touches.
I'm trying to create a custom transition, to serve as a replacement for a default transition you would get here, for example:
[self.navigationController pushViewController:someController animated:YES];
I have prepared an OpenGL-based view that performs an effect on some static texture mapped to a plane (let's say it's a copy of the flip effect in Core Animation). What I don't know how to do is:
grab current view content and make a texture out of it (I remember seeing a function that does just that, but can't find it)
how to do the same for the view that is currently offscreen and is going to replace current view
are there some APIs I can hook to in order to make my transition class as native as possible (make it a kind of Core Animation effect)?
Any thoughts or links are greatly appreciated!
UPDATE
Jeffrey Forbes's answer works great as a solution to capture the content of a view.
What I haven't figured out yet is how to capture the content of the view I want to transition to, which should be invisible until the transition is done.
Also, which method should I use to present the OpenGL view?
For demonstration purposes I used pushViewController. That affects the navbar, though, which I actually want to go one item back, with animation, check this vid for explanation:
http://vimeo.com/4649397.
Another option would be to go with presentViewController, but that shows fullscreen.
Do you think maybe creating another window (or view?) could be useful?
While I cannot completely answer your question without doing some more research of my own, I can help a bit:
-In order to get the view of a UINavigationController, you need to take a screenshot. The easiest way to do this is by grabbing it into a UIImage:
UIGraphicsBeginImageContext(self.view.frame.size);
[[self.view layer] renderInContext:UIGraphicsGetCurrentContext()];
UIImage* test = UIGraphicsGetImageFromCurrentImageContext();
UIImageView* view = [[UIImageView alloc] initWithImage:test];
UIGraphicsEndImageContext();
I am not sure if you can render a GLContext (not familiar on the phone) into a CGImage, but I would do something like that (and init a UIImage from that). I would prerender every frame of the animation you are trying to do and slap it into an UIImageView using the animation stuff provided within. That is, if your animation is simple enough. Otherwise, it might come down to writing your own animation function :-/
I have just put together a transition class to implement your own transition animation in OpenGL ES.
Feel free to read about it here
There are two example transitions in the project, feel free to add you own to it.
I think the function you might be thinking of is http://www.opengl.org/sdk/docs/man/xhtml/glCopyTexImage2D.xml ... you set the viewport to the texture size and then draw as usual, then do glCopyTexImage2D to copy the scene onto a texture.
or you should look into FrameBuffer Objects. The default OpenGL template in XCode uses these. Just generate the example project to see how those work.
I recently write some transitioning animation betweeen view controllers like you. If you want to get any extra info from the invisible view, you can try delaying the transition like this :
- (void)animationFromModalView:(UIView *)modalView toMasterView:(UIView *)masterView
{
[masterView setNeedsLayout];
[masterView layoutIfNeeded];
[self performSelector:#selector(delayAnimationFromModalViewToMasterView) withObject:nil afterDelay:.1f];
}