单点触控

package com.bwie.touch;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class TouchEvent extends View {

public float x=50;//刚进入时小球的位置
public float y=60;
public TouchEvent(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
Paint paint=new Paint();
//设置画笔的颜色
paint.setColor(Color.CYAN);
//画一个小球
canvas.drawCircle(x, y, 20, paint);

}
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
//获得该小球的x,y
this.x=event.getX();
this.y=event.getY();
//通知该组件重绘
this.invalidate();
//返回true表明处理方法已经处理该事件
return true;
}

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<com.bwie.touch.TouchEvent
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>

</RelativeLayout>