如何显式动画CALayer的backgroundColor？ [英] How do you explicitly animate a CALayer's backgroundColor?

问题描述

我试图构造一个CABasicAnimation动画的Core Animation CALayer的backgroundColor属性，但我不知道如何正确包装一个CGColorRef值传递到动画。例如：

  CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB 
 CGFloat values [4] = {1.0，0.0，0.0，1.0}; 
 CGColorRef red = CGColorCreate（rgbColorspace，values）; 
 CGColorSpaceRelease（rgbColorspace）; 
 
 CABasicAnimation * selectionAnimation = [CABasicAnimation animationWithKeyPath：@backgroundColor]; 
 [selectionAnimation setDuration：0.5f]; 
 [selectionAnimation setToValue：[NSValue valueWithPointer：red]]; 
 [layer addAnimation：selectionAnimation forKey：@selectionAnimation]; 
  

似乎对backgroundColor属性没有任何作用，我认为因为把它作为指针NSValue不是通过它的方式。

backgroundColor是CALayer的一个动画属性，所以我的问题是：如何为这个特定属性设置From或To值（最好在Mac /

c> c> 当设置 CABasicAnimation 的 toValue 或 fromValue 属性时， 。只需使用 CGColorRef 。为避免编译器警告，可以将 CGColorRef 转换为 id 。

在我的示例应用程序中，以下代码将背景设置为红色。

  CABasicAnimation * selectionAnimation = [CABasicAnimation 
 animationWithKeyPath：@backgroundColor]]; 
 selectionAnimation.toValue =（id）[UIColor redColor] .CGColor; 
 [self.view.layer addAnimation：selectionAnimation 
 forKey：@selectionAnimation]; 
  

但是，当动画结束时，背景返回到原始颜色。这是因为 CABasicAnimation 仅在动画运行时影响目标图层的表示层。动画完成后，将返回在模型层中设置的值。因此，您必须将图层 backgroundColor 属性设置为红色。可以使用 CATransaction 关闭隐式动画。

您可以使用隐式动画第一名。

I'm trying to construct a CABasicAnimation to animate the backgroundColor property of a Core Animation CALayer, but I can't figure out how to properly wrap a CGColorRef value to pass to the animation. For example:

CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB();
CGFloat values[4] = {1.0, 0.0, 0.0, 1.0}; 
CGColorRef red = CGColorCreate(rgbColorspace, values); 
CGColorSpaceRelease(rgbColorspace);

CABasicAnimation *selectionAnimation = [CABasicAnimation animationWithKeyPath:@"backgroundColor"];
[selectionAnimation setDuration:0.5f];
[selectionAnimation setToValue:[NSValue valueWithPointer:red]];
[layer addAnimation:selectionAnimation forKey:@"selectionAnimation"];

seems to do nothing to the backgroundColor property, I assume because handing it off as a pointer wrapped in an NSValue is not the way to pass it along.

backgroundColor is an animatable property of CALayer, so my question is: how do you set the From or To values for this particular property (preferably in a Mac / iPhone platform-independent way)?

解决方案

You don't need to wrap CGColorRefs when setting the toValue or fromValue properties of a CABasicAnimation. Simply use the CGColorRef. To avoid the compiler warning, you can cast the CGColorRef to an id.

In my sample app, the following code animated the background to red.

CABasicAnimation* selectionAnimation = [CABasicAnimation 
    animationWithKeyPath:@"backgroundColor"];
selectionAnimation.toValue = (id)[UIColor redColor].CGColor;
[self.view.layer addAnimation:selectionAnimation
                       forKey:@"selectionAnimation"];

However, when the animation is over, the background returns to the original color. This is because the CABasicAnimation only effects the presentation layer of the target layer while the animation is running. After the animation finishes, the value set in the model layer returns. So you are going to have to set the layers backgroundColor property to red as well. Perhaps turn off the implicit animations using a CATransaction.

You could save yourself this trouble by using an implicit animation in the first place.

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