1 
 hI,

 I am workng on animation using CALayer and CAPath.

 Here I am animating an Image from top to bottom of screen.I gave starting and ending position for
 the animation.Now, I want to get position  during the animation.

Sample Code:

   - (void)onTimer
    {

    CGImageRef imageRef = [[UIImage imageNamed:@"apple.png"] CGImage];
int startX                      = round(random() % 460);
double speed     = 1 / round(random() %100) + 1.0;

layer          = [CALayer layer];
layer.name              = @"layer";
layer.contents          = (id)imageRef; // cached image
layer.frame             = CGRectMake(startX, self.view.frame.size.height+10,    CGImageGetWidth(imageRef), CGImageGetHeight(imageRef));

[mView.layer addSublayer:layer];


 path = CGPathCreateMutable(); 
CGPathMoveToPoint(path, NULL, startX, -100);
CGPathAddLineToPoint(path, NULL, startX, self.view.frame.size.height+10);



CAKeyframeAnimation *animation= [CAKeyframeAnimation animationWithKeyPath:@"position"];

animation.delegate=self;

animation.duration= 10*speed;
animation.autoreverses=NO;
animation.path=path;
animation.repeatCount = 0;
animation.removedOnCompletion=YES;
animation.calculationMode = kCAAnimationLinear;

[layer addAnimation:animation forKey:@"position"];


CGPoint point= CGPathGetCurrentPoint(path);


   }

    In this I used "CGPathGetCurrentPoint" method but it did not work. Also used 
     presentationLayer method of CALayer but uit also did not work in this case.

     Can anyone suggest the code to get the position during animation
    thanks in advance
4

2 回答 2

2

您可以通过查看图层的presentationLayer 上的属性来获取动画期间在屏幕上看到的内容的值。

于 2011-08-10T23:11:14.717 回答
1

Core Animation 不是为此而设计的。它的工作是为您处理属性动画，而不是让您接触它。

如果你想知道它在动画过程中的位置，那么你需要在没有 Core Animation 的情况下自己完成所有的动画。

CGPathGetCurrentPoint()是一个访问CGPath实例控制点的函数，而不是 Core Animation 关键帧动画路径。

于 2011-05-04T03:33:06.750 回答