如何对UIBezierPath进行动画处理 [英] How to Animate a UIBezierPath

问题描述

我想将矩形的UIBezierPath设置为三角形，而不是对路径上的视图进行动画处理，而是对路径本身进行动画处理，以使其从一种形状变形为另一种形状.路径已添加到CALayer

CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.fillColor = [[UIColor whiteColor] CGColor];    
maskLayer.path = [self getRectPath];

-(CGPathRef)getTrianglePath
{
    UIBezierPath* triangle = [UIBezierPath bezierPath];
    [triangle moveToPoint:CGPointZero];
    [triangle addLineToPoint:CGPointMake(width(self.view),0)];
    [triangle addLineToPoint:CGPointMake(0, height(self.view))];
    [triangle closePath];
    return [triangle CGPath];
}

-(CGPathRef)getRectPath
{
    UIBezierPath*rect = [UIBezierPath bezierPathWithRect:self.view.frame];
    return [rect CGPath];
}

解决方案

我不是CoreAnimation的专家，但是您可以按以下方式定义CABasicAnimation

CABasicAnimation *morph = [CABasicAnimation animationWithKeyPath:@"path"];
morph.duration = 5;
morph.toValue = (id) [self getTrianglePath];
[maskLayer addAnimation:morph forKey:nil];

第一行指出您要定义一个动画，该动画会更改图层的path属性.第二行指出动画需要五秒钟，第三行指出动画的最终状态.最后，我们将动画添加到图层.关键点是动画的唯一标识符，也就是说，如果您添加两个具有相同关键点的动画，则仅考虑最后一个.该键也可以用于覆盖所谓的隐式动画.默认情况下，CALayer的几个属性是动画的.更准确地说，如果您更改这些属性之一，则更改将以0.25的持续时间进行动画处理.

i would like to animate a UIBezierPath of a rect to a triangle one, not to animate a view on a path but animate the path itself so it morphs from one shape to another. the path is added to a CALayer

CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.fillColor = [[UIColor whiteColor] CGColor];    
maskLayer.path = [self getRectPath];

-(CGPathRef)getTrianglePath
{
    UIBezierPath* triangle = [UIBezierPath bezierPath];
    [triangle moveToPoint:CGPointZero];
    [triangle addLineToPoint:CGPointMake(width(self.view),0)];
    [triangle addLineToPoint:CGPointMake(0, height(self.view))];
    [triangle closePath];
    return [triangle CGPath];
}

-(CGPathRef)getRectPath
{
    UIBezierPath*rect = [UIBezierPath bezierPathWithRect:self.view.frame];
    return [rect CGPath];
}

解决方案

I am not an expert on CoreAnimation but you can define a CABasicAnimation as follows

CABasicAnimation *morph = [CABasicAnimation animationWithKeyPath:@"path"];
morph.duration = 5;
morph.toValue = (id) [self getTrianglePath];
[maskLayer addAnimation:morph forKey:nil];

The first line states that you want to define an animation that changes the path property of the layer. The second line states that the animation takes five seconds and the third line gives the final state of the animation. Finally, we add the animation to the layer. The key is a unique identifier for the animation, that is, if you add two animations with the same key only the last one is considered. This key can also be used to override so called implicit animations. There are a couple of properties of a CALayer that are animated by default. More precisely, if you change one of these properties the change will be animated with a duration of 0.25.

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