随意拖拽的控件

代码过于简单，截图不付了，就是随意拖拽某个控件

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >


    <ImageView
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:src="@drawable/icon" />

</LinearLayout>

DraftTest

package com.oppo.examples;

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;

public class DraftTest extends Activity implements OnTouchListener{
	int screenWidth;
	int screenHeight;
	int lastX;
	int lastY;
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		DisplayMetrics dm = getResources().getDisplayMetrics();
		screenWidth = dm.widthPixels;
		screenHeight = dm.heightPixels;
		ImageView imageView=(ImageView)findViewById(R.id.btn2);
		imageView.setOnTouchListener(this);
	}

	@Override
	public boolean onTouch(View v, MotionEvent event) {
		int action=event.getAction();
		switch(action){
		case MotionEvent.ACTION_DOWN:
			lastX = (int) event.getRawX();
			lastY = (int) event.getRawY();
			break;
		case MotionEvent.ACTION_MOVE:
			//获取移动的距离
			int dx =(int)event.getRawX() - lastX;
			int dy =(int)event.getRawY() - lastY;
		
			//获取最新的坐标
			int left = v.getLeft() + dx;
			int top = v.getTop() + dy;
			int right = v.getRight() + dx;
			int bottom = v.getBottom() + dy;
			//屏蔽非法值
			if(left < 0){
				left = 0;
				right = left + v.getWidth();
			}					
			if(right > screenWidth){
				right = screenWidth;
				left = right - v.getWidth();
			}					
			if(top < 0){
				top = 0;
				bottom = top + v.getHeight();
			}					
			if(bottom > screenHeight){
				bottom = screenHeight;
				top = bottom - v.getHeight();
			}					
			v.layout(left, top, right, bottom);
			lastX = (int) event.getRawX();
			lastY = (int) event.getRawY();					
			break;
		case MotionEvent.ACTION_UP:
			break;        		
		}
		return false;	
	}
}