可自由拖动的ImageView

package com.ywm.myView;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.Window;
import android.widget.ImageView;

/**
 * 可自由拖动的ImageView
 * 
 * @author wey
 * 
 */
public class DragableView extends ImageView {

	public DragableView(Context context) {
		super(context);
		mContext = context;

		// TODO Auto-generated constructor stub
	}

	private Context mContext;

	public DragableView(Context context, AttributeSet attrs) {
		super(context, attrs);
		mContext = context;

	}

	public DragableView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mContext = context;

	}

	private float x = 0;
	private float y = 0;
	private int defaultHeight = 70; //

	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);
	}

	/**
	 * 获得状态栏和标题栏的高度
	 * 
	 * @return
	 */
	private int getStatusAndTitleBarHeight() {
		Activity ac = (Activity) mContext;

		Rect frame = new Rect();
		ac.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
		int statusBarHeight = frame.top; // 状态栏高度

		int contentTop = ac.getWindow().findViewById(Window.ID_ANDROID_CONTENT)
				.getTop();
		// statusBarHeight是上面所求的状态栏的高度
		int titleBarHeight = contentTop - statusBarHeight; // 标题栏高度
		return statusBarHeight + titleBarHeight;
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {

		// TODO Auto-generated method stub
		switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN:
				defaultHeight = getStatusAndTitleBarHeight();
				// 触控笔按下
				x = event.getX();
				// 得到X坐标
				y = event.getY() + defaultHeight; // 要减去标题栏和状态栏高度
				//
				break;
			case MotionEvent.ACTION_MOVE:
				int xx = (int) (event.getRawX() - x);
				int yy = (int) (event.getRawY() - y);

				this.layout(xx, yy, xx + getWidth(), yy + getHeight());
				// ViewGroup.LayoutParams lp = new LayoutParams(
				// LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT,
				// (int) event.getRawX() - x, (int) event.getRawY() - y);
				// this.setLayoutParams(lp);
				break;

			default:
				break;
		}
		return true;

	}
}