We need a special value for different part of animation @param part - needed part @return - value for needed part

On drawing we should check current part of animation @param part - needed part of animation @return - return true if current part

Get part of animation duration @param part - needed part of time @return - interval of time

修改状态。注：状态的改变与前一个状态以及下拉头高度有关 @param state

Set the absolute color of the progress spinner. This is should only be used when animating between current and next color when the spinner is rotating

@param index Index into the color array of the color to display in the progress spinner.

确保Target非空

Pre API 11, this does an alpha animation. @param progress

设置mCircleView的偏移量 同时更新mCurrentTargetOffsetTop @param offset 偏移量，可正可负 @param requiresUpdate 界面是否需要重绘invalidate();

@return The amount the progress spinner is currently rotated, between [0..1].

@param strokeWidth Set the stroke width of the progress spinner in pixels.

回滚动画

回滚动画

Pre API 11, alpha is used to make the progress circle appear instead of scale.

通过调用setTargetOffsetTopAndBottom()方法移动下拉组件Spinner（mCircleView） 同时更新mProgress（一个drawable）的绘制进度 @param overscrollTop 下拉高度

@param show Set to true to show the arrow head on the progress spinner.

通过调用offsetTopAndBottom方法 更新mTarget和mBaseRefreshView的位置 更新target下拉高度--mCurrentOffsetTop @param offset 偏移位移 @param requiresUpdate 时候invalidate(

通过调用offsetTopAndBottom方法 更新mTarget和mBaseRefreshView的位置 更新target下拉高度--mCurrentOffsetTop @param offset 偏移位移 @param requiresUpdate 时候invalidate()

@return Whether it is possible for the child view of this layout to scroll up. Override this if the child view is a custom view.

Draw wind on loading animation @param canvas - area where we will draw @param y - y position fot one of lines @param xOffset - x offset for on

手指松开后，处理下拉组件Spinner 设置开始刷新的动画，或者 将下拉组件Spinner回滚隐藏 @param overscrollTop 下拉距离