在main.xml文件中代码如下：
<?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" >
<com.tarena.touch.MyPaintView
android:id="@+id/paintView"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</LinearLayout>
在MyPaintView.java中代码如下：
package com.tarena.touch;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class MyPaintView extends View{
private List<Point> allPoint = new ArrayList<Point>(); //保存所有的操作坐标
public MyPaintView(Context context, AttributeSet attrs) { //接收Context，同时接收属性集合
super(context, attrs); //调用父类的构造
super.setOnTouchListener(new OnTouchListenerImpl());
}
private class OnTouchListenerImpl implements OnTouchListener{
public boolean onTouch(View v, MotionEvent event) {
Point p = new Point((int) event.getX(),(int) event.getY()); //将坐标保存在Point类中
if(event.getAction() == MotionEvent.ACTION_DOWN){ //用户按下
MyPaintView.this.allPoint = new ArrayList<Point>(); //重绘
MyPaintView.this.allPoint.add(p); //保存新的点
}
else if(event.getAction() == MotionEvent.ACTION_UP){ //用户松开
MyPaintView.this.allPoint.add(p); //记录坐标点
MyPaintView.this.postInvalidate(); //重绘图形
}
else if(event.getAction() == MotionEvent.ACTION_MOVE){ //用户移动
MyPaintView.this.allPoint.add(p); //记录坐标点
MyPaintView.this.postInvalidate(); //重绘图形
}
return true; //表示下面的操作不再执行
}
}
protected void onDraw(Canvas canvas){ //进行重绘
Paint p = new Paint(); //依靠此类开始画线
p.setColor(Color.RED); //定义线的颜色
if(MyPaintView.this.allPoint.size() > 1){ // 有坐标点保存的时候开始绘图
Iterator<Point> iter = MyPaintView.this.allPoint.iterator();
Point first = null; //开始的坐标点
Point last = null; //结束的坐标点
while(iter.hasNext()){
if(first == null){
first = (Point) iter.next(); //现在没有在绘图，取出坐标
}
else{
if(last != null){ //前一阶段已经完成
first = last; //重新更新下一阶段
}
last = (Point) iter.next(); //结束点坐标
canvas.drawLine(first.x, first.y, last.x, last.y, p);
}
}
}
}
}
在MyTouchDemo.java中代码如下：
package com.tarena.touch;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;
public class MyTouchDemo extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.main);
}
}