Android -- 自定义View小Demo（一）

1，现在要实现下图的简单效果，很简单  ，就是使用paint在canvas上绘制5中不同颜色的圆圈，效果图如下：

这是绘制基本图形一种最简单的方法，下面是它的代码 ，注释写的很详细，也就不去讲解了

MyCircleView.java

package com.wangjitao.myview.view;

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

/**
 * Created by wangjitao on 2016/10/10 0010.
 * 绘制类似于奥运五环的圆圈
 */
public class MyCircleView extends View {


    public MyCircleView(Context context) {
        super(context);
    }

    public MyCircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MyCircleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //定义一个默认的画笔
        Paint paint = new Paint();
        //绘制画布为白色
        canvas.drawColor(Color.WHITE);
        //设置抗锯齿功能
        paint.setAntiAlias(true);
        //设置画笔的宽度
        paint.setStrokeWidth(3);
        //设置画笔填充的样式
        paint.setStyle(Paint.Style.STROKE);

        //绘制蓝色圆环
        paint.setColor(Color.BLUE);
        canvas.drawCircle(250, 250, 150, paint);

        //绘制黄色圆环
        paint.setColor(Color.YELLOW);
        canvas.drawCircle(500, 250, 150, paint);

        //绘制黑色圆环
        paint.setColor(Color.BLACK);
        canvas.drawCircle(750, 250, 150, paint);

        //绘制绿色圆环
        paint.setColor(Color.GREEN);
        canvas.drawCircle(375, 450, 150, paint);

        //绘制红色圆环
        paint.setColor(Color.BLUE);
        canvas.drawCircle(625, 450, 150, paint);
    }
}