android api Scroller类翻译

Scroller类：存在于android.widget包，直接继承至Object类

类概述：

该类封装了滚动。 你可以使用Scroller或者OverScroller类的实例去收集你需要产生滚动动画的数据，例如抛掷手势。该实例随时不断的追踪滚动效果的偏移量，但是不会自动将这些数据应用到你的view上。你要做的就是以一定的频率去得到并应用这些新的坐标，从而使滑动动画看起来更加平滑。

private Scroller mScroller = new Scroller(context);
 ...
 public void zoomIn() {
     // Revert any animation currently in progress 将当前正在执行的动画复位
     mScroller.forceFinished(true);
     // Start scrolling by providing a starting point and
     // the distance to travel  设置开始坐标和x，y轴上的偏移量，调用startScroll（。。。）
     mScroller.startScroll(0, 0, 100, 0);
     // Invalidate to request a redraw 迫使view重绘
     invalidate();
 }

if (mScroller.computeScrollOffset()) {
     // Get current x and y positions
     int currX = mScroller.getCurrX();
     int currY = mScroller.getCurrY();
    ...
 }
computeSCrolloffeset()方法会计算当前的偏移量，返回true表示当前滚动动画正在进行中，返回false表示已停止。

该类的方法如下：

  

      
       void
      

      
       abortAnimation()
       
      

       Stops
 the animation.
      

      
       boolean
      

      
       computeScrollOffset()
       
      

       Call
 this when you want to know the new location.
      

      
       void
      

      
       extendDuration(int
 extend)
       
      

       Extend the scroll animation.
      

      
       void
      

      
       fling(int
 startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY)
       
      

       Start scrolling based on a fling gesture.
      

      
       final void
      

      
       forceFinished(boolean
 finished)
       
      

       Force the finished field to a particular value.
      

      
       float
      

      
       getCurrVelocity()
       
      

       Returns
 the current velocity.
      

      
       final int
      

      
       getCurrX()
       
      

       Returns
 the current X offset in the scroll.
      

      
       final int
      

      
       getCurrY()
       
      

       Returns
 the current Y offset in the scroll.
      

      
       final int
      

      
       getDuration()
       
      

       Returns
 how long the scroll event will take, in milliseconds.
      

      
       final int
      

      
       getFinalX()
       
      

       Returns
 where the scroll will end.
      

      
       final int
      

      
       getFinalY()
       
      

       Returns
 where the scroll will end.
      

      
       final int
      

      
       getStartX()
       
      

       Returns
 the start X offset in the scroll.
      

      
       final int
      

      
       getStartY()
       
      

       Returns
 the start Y offset in the scroll.
      

      
       final boolean
      

      
       isFinished()
       
      

       Returns
 whether the scroller has finished scrolling.
      

      
       void
      

      
       setFinalX(int
 newX)
       
      

       Sets the final position (X) for this scroller.
      

      
       void
      

      
       setFinalY(int
 newY)
       
      

       Sets the final position (Y) for this scroller.
      

      
       final void
      

      
       setFriction(float
 friction)
       
      

       The amount of friction applied to flings.
      

      
       void
      

      
       startScroll(int
 startX, int startY, int dx, int dy)
       
      

       Start scrolling by providing a starting point and the distance to travel.
      

      
       void
      

      
       startScroll(int
 startX, int startY, int dx, int dy, int duration)
       
      

       Start scrolling by providing a starting point, the distance to travel, and the duration of the scroll.
      

      
       int
      

      
       timePassed()
       
      

       Returns
 the time elapsed since the beginning of the scrolling.