Android使用继承View类来绘图

添加新类MyView继承View

在MyView中实例化Paint

package com.hu.viewdemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Path;
import android.view.View;

public class MyView extends View{

    private Paint paint;//画笔
    
    public MyView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        paint = new Paint();
        paint.setColor(Color.RED);//设置画笔颜色
        paint.setAntiAlias(true);//设置抗锯齿
        paint.setStyle(Style.STROKE);//设置为空心
        paint.setStrokeWidth(1);//设置空心边距为1
        paint.setTextSize(40);//设置字符串高
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        canvas.drawCircle(100, 100, 20, paint);//画个圆
        canvas.drawText("这是字符串", 0, 40, paint);//写字,指定左下角位置
        canvas.drawRect(100, 200, 200, 300, paint);//画矩形
        Path path=new Path();//创建路径
        path.moveTo(300, 200);
        path.lineTo(300, 300);
        path.lineTo(200, 400);//指定路径
        canvas.drawPath(path, paint);//沿路径绘图
    }

}

然后在activity类中将MyView的实例设为ContentView

package com.hu.viewdemo;

import android.app.Activity;
import android.os.Bundle;

public class ViewDemoActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        MyView mv=new MyView(this);
        setContentView(mv);
    }
}