Android 简单画个渐变圆环

先上效果图

微信图片编辑_20200516150648.jpg

然后上代码（注释应该蛮清晰了吧，有需要随便改改就能用咯）

public class ArcChart extends View {
    //外部传入的比例参数
    private final float arrPer;
    //RGB颜色数组 为渐变准备为数组，起始颜色值和终止颜色值
    private final int[] mMinColors = {Color.parseColor("#FF8359"), Color.parseColor("#FFDF40")};

    public ArcChart(Context context, float getArrPer) {
        super(context);
        arrPer = getArrPer;
    }

    public void onDraw(Canvas canvas) {
        DisplayMetrics dm = getResources().getDisplayMetrics();
        int screenWidth = dm.widthPixels;//这里是控件view的宽度，设置为了屏幕宽度
        float mMinOvalR = screenWidth / 6f; //圆环直径
        float mMinWidth = 90; //圆环宽度
        float startAngle = 90;//圆弧起始角度
        float degreeCircle = 180;//圆头位置
        float matrixStart = 90;//渐变旋转角度

        //创建画笔：
        Paint mMinPaint = new Paint();
        mMinPaint.setColor(Color.parseColor("#F9F9F9"));
        mMinPaint.setAntiAlias(true); //启用抗锯齿
        mMinPaint.setDither(true); //启用抗颜色抖动（可以让渐变更平缓）
        mMinPaint.setStyle(Paint.Style.STROKE);//圆弧
        mMinPaint.setStrokeWidth(mMinWidth);//圆环宽度


        //外接矩形
        //算出矩形顶点坐标。
        RectF rect = new RectF(canvas.getWidth() / 2 - mMinOvalR,
                canvas.getHeight() / 2 - mMinOvalR,
                canvas.getWidth() - (canvas.getWidth() / 2 - mMinOvalR),
                canvas.getHeight() - (canvas.getHeight() / 2 - mMinOvalR));
        canvas.drawArc(rect, 0, 360, false, mMinPaint);//先画一圈背景灰色圆环
        float degree = 360 * (arrPer / 100); //圆弧扫过的角度
        matrixStart += degree;//渐变旋转角度要开始计算
        //创建渐变
        SweepGradient mSweepGradient = new SweepGradient(canvas.getWidth() / 2,
                canvas.getHeight() / 2,
                mMinColors,
                new float[]{0f, degree});
        Matrix matrix = new Matrix();//将渐变旋转
        matrix.setRotate(matrixStart, canvas.getWidth() / 2, canvas.getHeight() / 2);
        mSweepGradient.setLocalMatrix(matrix);
        //把渐变设置到笔刷
        mMinPaint.setShader(mSweepGradient);
        //画渐变的弧
        canvas.drawArc(rect, startAngle, degree, false, mMinPaint);
        //记录下位置
        float[] arrayInt = {0, arrPer};
        //获取渐变弧结束点的颜色值和渐变的开始值
        int[] newColor = {Color.rgb(255,
                (int) (223 + (-0.92 * arrPer)), (int) (64 + (0.25 * arrPer))), mMinColors[1]};
        //画圆弧开始和结束的圆点
        for (int i = 0; i < 2; i++) {
            Paint mMinCirclePaint = new Paint();//定义头部画笔
            mMinCirclePaint.setColor(newColor[i]);//取颜色值
            mMinCirclePaint.setAntiAlias(true);//启用抗锯齿
            degreeCircle += 360 * (arrayInt[i] / 100); //圆位置等于圆弧长度
            float mDegreeCircle = degreeCircle - 90;//抵消屏幕坐标系差异
            mDegreeCircle = (float) (Math.PI / 180f * mDegreeCircle); //换成弧度
            canvas.drawCircle((float) (rect.left + rect.width() / 2f + mMinOvalR * Math.cos(mDegreeCircle)), //圆心x
                    (float) (rect.top + rect.height() / 2f + mMinOvalR * Math.sin(mDegreeCircle)), //圆心y
                    mMinWidth / 2f,  //半径
                    mMinCirclePaint);
        }
    }
}

使用的时候直接new ArcChart(this, 0.5f);就行啦

主要是用SweepGradient来叠加渐变色，但是我发现似乎少于360度的圆弧无法根据传入的颜色值进行完全的渐变，所以我上面代码只能通过获取圆弧结束点的颜色值来达到结束点的圆角效果

要是有人知道怎么解决这个问题麻烦留言告知一下哦