创建安卓应用

创建custom

定义变量

构造方法，初始化画笔

绘制方法–绘制兔子

package net.zjs.draw_circle_view;


import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.view.View;

public class CustomView extends View {
    private Paint paint;//画笔
    private int screenWidth;//屏幕宽度
    private int screenHeight;//屏幕高度


    /*
    * 构造方法--初始化画笔
    * */
    public CustomView(Context context) {
        super(context);
        //实例化画笔
        paint=new Paint();
        //设置画笔防锯齿形
        paint.setAntiAlias(true);
//        //设置画笔颜色
//        paint.setColor(Color.BLACK);
        //获取屏幕宽度
        screenWidth=((Activity) context).getWindowManager().getDefaultDisplay().getWidth();
        //获取屏幕高度
        screenHeight=((Activity) context).getWindowManager().getDefaultDisplay().getHeight();
    }

    /*
    * 绘制方法
    * 绘制兔子*/
    protected void onDraw(Canvas canvas){
        super.onDraw(canvas);
        //设置画笔颜色--黑色
        paint.setColor(Color.BLACK);
        //
        paint.setStyle(Paint.Style.STROKE);
        //绘制椭圆(设置其大小)--左耳朵
        canvas.drawArc(new RectF(200,200,400,1000),0,360,true,paint);
        //绘制椭圆（右耳朵）
        canvas.drawArc(new RectF(700,200,900,1000),0,360,true,paint);

        //绘制圆（脸）
        paint.setColor(Color.WHITE);
        paint.setStyle(Paint.Style.FILL);
        canvas.drawCircle(550,1200,500,paint);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);//空心圆
        canvas.drawCircle(550,1200,500,paint);


        //绘制实心圆（眼睛）
        paint.setStyle(Paint.Style.FILL);
        canvas.drawCircle(350,1100,40,paint);
        canvas.drawCircle(750,1100,40,paint);


        //直线（嘴）
        canvas.drawLine(300,1400,800,1400,paint);

        //矩形（牙齿）
        paint.setStyle(Paint.Style.STROKE);
        canvas.drawRect(new Rect(400,1500,500,1400),paint);
        canvas.drawRect(new Rect(600,1500,700,1400),paint);


    }



}

编写主界面类

package net.zjs.draw_circle_view;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {
    private CustomView mCustomview;//声明自定义视图
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //实例化自定义视图
        mCustomview=new CustomView(this);
        //将自定义视图设置为用户界面
        setContentView(mCustomview);
    }

}

运行效果