android drawArc写的一个小例子

package com.fise.ctraffic.widget;

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

import androidx.annotation.Nullable;

/**
 * author : vincent
 * e-mail : jiaqiangmn@gmail.com
 * date   : 2020/9/30 13:59
 * desc   :
 * project_name: cellularTraffic
 */
public class UsedInfoCircle extends View {
    private Paint paint;

    public UsedInfoCircle(Context context) {
        super(context);
        init();
    }

    public UsedInfoCircle(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public UsedInfoCircle(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        paint = new Paint();
    }

    @Override
    protected void onDraw(Canvas canvas) {


//        设置画笔属性
//        paint.setStyle(Paint.Style.FILL);//画笔属性是实心圆
        paint.setStyle(Paint.Style.STROKE);//画笔属性是空心圆
        paint.setStrokeWidth(10);//设置画笔粗细

        float cx = getWidth() / 2;
        float cy = getHeight() / 2;
        float radius1 = cx - 10;
        float radius2 = radius1 - 10;//中间大面积的圆的半径
        paint.setAntiAlias(true);//抗锯齿


        paint.setColor(Color.parseColor("#0C3443"));
//        先画一个圆形底色
        canvas.drawCircle(cx, cy, radius1, paint);

        //添加渐变颜色
        @SuppressLint("DrawAllocation")
        int[] colors = new int[]{Color.parseColor("#FFE000"),
                Color.parseColor("#FFA011"),
                Color.parseColor("#FF3131"),
                Color.parseColor("#FF6222")
        };
        //添加渐变颜色改变点
        float[] f = new float[]{0.1f, 0.3f, 0.6f, 0.8f};
        //SweepGradient 的参数是： X中心点，Y中心点，颜色数组，渐变点数组
//        SweepGradient sweepGradient1 = new SweepGradient(cx, cy, colors, f);
//        paint.setShader(sweepGradient1);
//        canvas.drawCircle(cx, cy, radius1, paint);
//        paint.setShader(null);
        paint.setColor(Color.parseColor("#FFE000"));
        float left = (getWidth() - radius1 * 2) / 2;
        float top = left;
        float width = radius1 * 2 + left;
        RectF oval1 = new RectF(left, top, width, width);
        //startAngle 从3点钟方向开始
        //sweepAngle 顺时针扫过的角度
        canvas.drawArc(oval1, 0, 270, false, paint);

        //画实心的圆
//        paint.reset();
//        paint.setAntiAlias(true);//抗锯齿
//        paint.setStyle(Paint.Style.FILL);
//        paint.setColor(Color.parseColor("#00AEC3"));
//        canvas.drawCircle(cx, cy, radius2, paint);
    }
    //定义的圆弧的形状和大小的范围
//    RectF oval1=new RectF(width/2-100,height/2-100,width/2+100,height/2+100);
    //float startAngle设置圆弧是从哪个角度来顺时针绘画的
    //float sweepAngle 设置圆弧扫过的角度
    //boolean useCenter  设置我们的圆弧在绘画的时候，是否经过圆形。也就是是否会是扇形的图像()
//        canvas.drawArc(oval1, 270, Currentprogress, false, PaintCurrent);
//        canvas.drawText(Currentprogress*100f/Maxprogress+"%", width/2,height/2, PaintText);

}