Gradient 对象可以用来创建渐变样式或者动画。你需要使用两个颜色（开始色和结束色）以及一个表示方向的角度来描述一个渐变。

The Gradient object can be used to create, customize and animate gradients. It consists of two colors (start, end) and an angle indicating its direction.

gradient = new Gradient
    start: "#05F"
    end: "#0DF"

开始色和结束色也可以使用颜色对象。

The start and end values also accept Color objects.

gradient = new Gradient
    start: new Color("#05F")
    end: new Color("#0DF")

如果你想要画一个带有渐变背景色的图层，可以直接将创建的渐变对象赋给 layer.gradient 。

You can apply a gradient to a layer directly by using the layer.gradient property.

blue = new Gradient
    start: "#05F"
    end: "#0DF"
​
layerA = new Layer
    gradient: blue

渐变对象的所有属性都是可以进行过渡动画的。

All properties of the gradients object can be animated, too.

blue = new Gradient
    start: "#05F"
    end: "#0DF"
​
purple = new Gradient
    start: "#30F"
    end: "#B8F"
​
layerA = new Layer
    gradient: blue
​
layerA.animate
    gradient: purple

gradient.start <string>

开始色，默认是黑色。

The start color. Set to black by default.

gradient = new Gradient
    start: "#05F"

gradient.end <string>

结束色，默认是白色。

The end color. Set to white by default.

gradient = new Gradient
    start: "#05F"
    end: "#0DF"

gradient.angle <number>

渐变的方向角度，默认是 0° 。

The angle of the gradient. Set to 0 by default.

gradient = new Gradient
    start: "#0DF"
    end: "#05F"
    angle: 180