Android View实现圆形进度条

// 画圆
canvas.drawCircle
// 画圆弧
canvas.drawArc
// 画文本
canvas.drawText
// 抗锯齿
paint.setAntiAlias(true);
// 设置颜色
paint.setColor(getResources().getColor(mFGColor, null));

public class MyView extends View {
    // 线宽度
    private static final int mStrokeWidth = 50;
    private int mVal = 0;
    private static final int mMaxVal = 200;
    private int mGgColor = R.color.arcbg;
    private int mFgColor = R.color.arcfg;

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

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


    // 设置值
    public void setProgressValue(int val){
        this.mVal = val;
        invalidate();
    }


    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int width = getMeasuredWidth();
        int height = getMeasuredHeight();

        drawBGCircle(canvas, width, height);
        drawFGArc(canvas, width, height);
        drawText(canvas, width, height);
    }

    // 文本
    private void drawText(Canvas canvas, int width, int height) {
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(getResources().getColor(mFgColor, null));
        paint.setTextSize(120);
        int percent = (int) (( mVal / (float) mMaxVal ) * 100);
        canvas.drawText(percent + "%", (width - paint.measureText(percent + "%")) / 2, (height + paint.measureText("%")) / 2, paint);
    }

    // 圆弧
    private void drawFGArc(Canvas canvas, int width, int height) {
        Paint paint = new Paint();
        paint.setColor(getResources().getColor(mFgColor, null));
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(mStrokeWidth);
        paint.setAntiAlias(true);
        RectF mRectF = new RectF(mStrokeWidth, mStrokeWidth, width - mStrokeWidth, height - mStrokeWidth);
        int sweepAngle = (int) (360 * mVal / (float) mMaxVal);
        canvas.drawArc(mRectF, -90, sweepAngle, false, paint);
    }

    // 底部圆形
    private void drawBGCircle(Canvas canvas, int width, int height) {
        int r = (width - 2 * mStrokeWidth) / 2;
        Paint cPaint = new Paint();
        cPaint.setColor(getResources().getColor(mGgColor, null));
        cPaint.setStyle(Paint.Style.STROKE);
        cPaint.setStrokeWidth(mStrokeWidth);
        cPaint.setAntiAlias(true);
        canvas.drawCircle(width / 2, height / 2, r, cPaint);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int width = getSize(widthMeasureSpec, 200);
        int height = getSize(heightMeasureSpec, 200);
        setMeasuredDimension(width, height);
    }

    private int getSize(int widthMeasureSpec, int defultSize) {
        int realSize = defultSize;
        int mode = MeasureSpec.getMode(widthMeasureSpec);
        int size = MeasureSpec.getSize(widthMeasureSpec);
        switch (mode){
            case MeasureSpec.UNSPECIFIED:
                realSize = defultSize;
                break;
            case MeasureSpec.AT_MOST:
                realSize = size;
                break;
            case MeasureSpec.EXACTLY:
                realSize = size;
                break;
        }
        return realSize;
    }
}

<com.weizu.myapplication.view.MyView
        android:id="@+id/myView"
        android:layout_width="150dp"
        android:layout_height="150dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

MyView view = findViewById(R.id.myView);
view.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                int val = 0;
                while(val <= 200){
                    view.setProgressValue(val);
                    val++;
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
});