Android利用Canvas类绘制图形

package lession.example.com.learncanvas;

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

public class DrawPaint extends View {
    Paint pt;
    public DrawPaint(Context context) {
        super(context);
        pt = new Paint();//创建画笔
    }
    
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        pt.setARGB(255,255,0,0);
        pt.setStrokeWidth(3);
        pt.setStyle(Paint.Style.FILL);
        pt.setTextSize(60);
        //画圆
        canvas.drawText("圆：",80,120,pt);
        canvas.drawCircle(200,100,30,pt);
        //画矩形
        canvas.drawText("矩形：",80,220,pt);
        canvas.drawRect(250,180,400,250,pt);
        //正方形
        canvas.drawText("正方形：",80,320,pt);
        canvas.drawRect(290,290,370,370,pt);
        //圆角矩形
        canvas.drawText("圆角矩形：",80,440,pt);
        RectF rectF = new RectF(350,400,550,500);
        canvas.drawRoundRect(rectF,20,30,pt);
        //椭圆形
        canvas.drawText("椭圆形：",80,600,pt);
        RectF oval = new RectF(350,550,650,700);
        canvas.drawOval(oval,pt);
        //三角形
        canvas.drawText("三角形：",80,750,pt);
        Path path = new Path();
        path.moveTo(300,700);
        path.lineTo(300,800);
        path.lineTo(400,800);
        path.close();
        canvas.drawPath(path,pt);
        //五边形
        canvas.drawText("五边形：",80,900,pt);
        Path path1 = new Path();
        path1.moveTo(300,900);
        path1.lineTo(400,900);
        path1.lineTo(450,1000);
        path1.lineTo(400,1100);
        path1.lineTo(300,1100);
        path1.lineTo(300,1000);
        path1.close();
        canvas.drawPath(path1,pt);
    }
}

package lession.example.com.learncanvas;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.FrameLayout;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);
        DrawPaint MyPaint = new DrawPaint(MainActivity.this);
        setContentView(MyPaint);
    }
}