Android提高第十九篇之"多方向"抽屉

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

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 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！