Android提高之多方向抽屜實現方法

說起在android上要實現類似Launch的抽屜效果，大家一定首先會想起SlidingDrawer。SlidingDrawer是android官方控件之一，但是本文的主角並不是它，而是民間的控件工具集合：android-misc-widgets。android-misc-widgets裡面包含幾個widget：Panel、SmoothButton、Switcher、VirtualKeyboard,還有一些動畫特效，本文主要介紹抽屜容器Panel的用法。android-misc-widgets的google工程地址：-widgets/http://code.google.com/p/android-misc。

工程代碼中Panel的演示效果如下所示：

這個Panel控件可以輕易實現不同方向的抽屜效果，比SlidingDrawer有更強的擴展性！

在多次使用Panel的過程中，發現Panel有個bug，會間斷性出現“閃爍”，也就是在onTouchListener裡面的觸發ACTION_DOWN後，抽屜瞬間彈出然後瞬間回收(版本日期為Feb 3, 2009)。把原Panel的OnTouchListener加以替換，即以下代碼：

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;
 }
};

替換為：

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;
 }
};

即可修復這個bug，並且也同樣實現了OnClickListener的功能，可以把原Panel的OnClickListener給刪掉了！

希望本文所述實例對於大家進行Android項目開發能有所幫助。