Android中兑现物体在屏幕的移动

程序效果是：在屏幕上画一个圆，可以用鼠标任意移动到屏幕上任何一个地方：

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package com.ray.view;import android.app.Activity;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Bundle;import android.view.MotionEvent;import android.view.View;import android.view.Window;import android.view.WindowManager;public class TestView extends Activity {	float x = 0;	float y = 0;	View myView;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        //值得一提的是，由于画圆参照的坐标系(以系统信息栏的左下侧为原点)        //和MotionEvent获取的x,y坐标参照(以屏幕坐上角为原点)的坐标系不同，        //如果不设置全屏的话，会出现鼠标中心跟圆心不一致的情况。        requestWindowFeature(Window.FEATURE_NO_TITLE);           getWindow().setFlags(WindowManager.LayoutParams. FLAG_FULLSCREEN ,WindowManager.LayoutParams. FLAG_FULLSCREEN);          myView = new MyView(this);        setContentView(myView);      }    public boolean onTouchEvent(MotionEvent event) {		x = event.getX();		y = event.getY();		switch(event.getAction()){			case MotionEvent.ACTION_DOWN: 				myView.invalidate();				break;			case MotionEvent.ACTION_UP: 				myView.invalidate();				break;			case MotionEvent.ACTION_MOVE:				myView.invalidate();				break;		}				return super.onTouchEvent(event);	}    class MyView extends View{		protected void onDraw(Canvas canvas) {			Paint mPaint = new Paint();						mPaint.setColor(Color.BLUE);			mPaint.setAntiAlias(true);			canvas.drawCircle(x, y, 20, mPaint);			super.onDraw(canvas);				}		public MyView(Context context) {			super(context);		}				    }}

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1 楼 happyljt 2010-01-25  

学习了。