Android提高之多方向抽屉实现方法

说起在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，但是本文的主角并不是它，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的演示效果如下所示：

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加以替换，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 panel's 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();
  }
  touchX = event.getX();
  touchY = event.getY();
 }
 if (!mGestureDetector.onTouchEvent(event)) {
  if (action == MotionEvent.ACTION_UP) {
  // tup up after scrolling
  int size = (int) (Math.abs(touchX - event.getX()) + Math
   .abs(touchY - event.getY()));
  if (size == mContentWidth || size == mContentHeight) {
   mState = State.ABOUT_TO_ANIMATE;
   //Log.e("size", String.valueOf(size));
   //Log.e(String.valueOf(mContentWidth),String.valueOf(mContentHeight));
  }
  post(startAnimation);
  }
 }
 return false;
 }
};

即可修复这个bug，并且也同样实现了OnClickListener的功能，可以把原Panel的OnClickListener给删掉了！

希望本文所述实例对于大家进行Android项目开发能有所帮助。