Animation

Animation objects manage animations that target a layer and properties. An animation will tween between a start and end value, with a curve. The start value is determined when the animation starts, and the end value is defined by properties. If the start values equal to end values, they won't animate.
译：动画对象用来管理图层或者属性的动画。一个动画就是某个属性在起始值和结束值之间以一种运动曲线过渡。在动画开始时那些属性默认的值就是起始值，我们需要定义一下属性的结束值。如果它们相等就不会有动画效果。

Properties（属性值）

1. layer — 一个要被触发动画的图层对象.

2. properties — 该动画最终的一些属性值对象.

3. curve — 一个字符串，默认是“ease”。(可选的)

4. curveOptions — 带有运动曲线属性值的对象. (可选的)

5. time — 数字，代表动画运行多少秒. (可选的)

6. delay — 数字，动画延迟执行的时间 (可选的)

7. repeat — 数字, 动画重复的次数 (可选的)

8. colorModel — 字符串, 动画变幻时的颜色模式。(可选的)

Example: layer and properties（示例: 图层和属性变化）

Here, we create a new Animation for layerA. Once we start the animation, it will move horizontally from 0 to 100. Note that we left out many optional arguments. By default, the animation will take 1 second, with a ease curve.
译：这里我们给layerA设置一个新的动画。动画开始后这个图层就会从0水平移动到100.需要注意的是，有很多可选的动画参数我们没有写，那么这个动画就默认执行1秒，使用ease曲线。

layerA = new Layer

# Animate the layer to the right 
animationA = new Animation
    layer: layerA
    properties:
        x: 100

Example: multiple properties and time（示例: 多属性变化和动画时间）

Multiple properties can be animated at once. Here, we animate the x and opacity properties, with a duration of 5 seconds.
译：我们可以对多个属性同时执行动画。下面的代码就是在5秒内让图层的x坐标和透明度同时变化。

layerA = new Layer

# Animate multiple properties for 5 seconds 
animationB = new Animation
    layer: layerA
    properties:
        x: 100
        opacity: 0.5
    time: 5

Example: repeat and delay（示例: 重复和延迟）

When using repeat, the end values of properties will be reset to their starting position instantly. In the example below, there is a 2 second delay between every repeat.
译：当启用重复选项时，动画结束时变化的属性就会立即恢复到开始的状态。下面的例子中，图层的动画每次重复之间会有2秒的延迟。

# Repeat an animation 5 times, delay for 2 seconds 
animationD = new Animation
    layer: layerA
    properties:
        x: 100
    repeat: 5
    delay: 2

Example: ease-in-out（示例: ease-in-out）

Included easing curves are ease-in, ease-out and ease-in-out.
译：动画中已经包含的动画曲线有ease-in, ease-out和ease-in-out。

# Animate with an ease-in-out curve 
animationE = new Animation
    layer: layerA
    properties:
        x: 100
    curve: "ease-in-out"