Android提高第十九篇之 多方向 抽屉

摘自blog.csdn.net/hellogv

       在android上要实现类似Launch的抽屉效果，大家一定首先会想起SlidingDrawer。SlidingDrawer是android官方控件之一，本文的主角不是它，而是民间的控件工具集合~~~android-misc-widgets。android-misc-widgets里面包含几个widget：Panel、SmoothButton、Switcher、VirtualKeyboard,还有一些动画特效，本文主要介绍抽屉容器Panel的用法。android-misc-widgets的google工程地址：-widgets/http://code.google.com/p/android-misc，工程代码中Panel的演示效果如下：

       这个Panel控件可以轻易实现不同方向的抽屉效果，比SlidingDrawer有更强的扩展性！

       在多次使用Panel的过程中，发现Panel有个bug，会间断性出现“闪烁”，也就是在onTouchListener里面的触发ACTION_DOWN后，抽屉瞬间弹出然后瞬间回收(版本日期为Feb 3, 2009)。把原Panel的OnTouchListener，即以下代码：

 OnTouchListener touchListener = new OnTouchListener() {
  int initX;
  int initY;
  boolean setInitialPosition;
  public boolean onTouch(View v, MotionEvent event) {
   if (mState == State.ANIMATING) {
    // we are animating
    return false;
   }
//   Log.d(TAG, "state: " + mState + " x: " + event.getX() + " y: " + event.getY());
   int action = event.getAction();
   if (action == MotionEvent.ACTION_DOWN) {
    if (mBringToFront) {
     bringToFront();
    }
    initX = 0;
    initY = 0;
    if (mContent.getVisibility() == GONE) {
     // since we may not know content dimensions we use factors here
     if (mOrientation == VERTICAL) {
      initY = mPosition == TOP? -1 : 1;
     } else {
      initX = mPosition == LEFT? -1 : 1;
     }
    }
    setInitialPosition = true;
   } else {
    if (setInitialPosition) {
     // now we know content dimensions, so we multiply factors...
     initX *= mContentWidth;
     initY *= mContentHeight;
     // ... and set initial panels position
     mGestureListener.setScroll(initX, initY);
     setInitialPosition = false;
     // for offsetLocation we have to invert values
     initX = -initX;
     initY = -initY;
    }
    // offset every ACTION_MOVE & ACTION_UP event
    event.offsetLocation(initX, initY);
   }
   if (!mGestureDetector.onTouchEvent(event)) {
    if (action == MotionEvent.ACTION_UP) {
     // tup up after scrolling
     post(startAnimation);
    }
   }
   return false;
  }
 };

替换为：

 OnTouchListener touchListener = new OnTouchListener() {
  float touchX, touchY;

  public boolean onTouch(View v, MotionEvent event) {
   if (mState == State.ANIMATING) {
    // we are animating
    return false;
   }

   int action = event.getAction();
   if (action == MotionEvent.ACTION_DOWN) {
    if (mBringToFront) {
     bringToFront();
    }