canvas.drawText("弧度：" + currentAngle, rectF.centerX()-textWidth/2 , rectF.bottom , mArrowPaint);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
<BUG>width = getWidth();

height = getHeight();

mRingCenterRadius = Math.min(width, height);
rectF.set((float) (width / 2 - (SecondRadius + result)), (float) (height / 2 - (SecondRadius + result)), (float) (width

/ 2 + (SecondRadius + result)), (float) (height / 2 + (SecondRadius + result)));
</BUG>
centerX = rectF.centerX();

canvas.drawText("弧度：" + currentAngle, rectF.centerX()-textWidth/2 , rectF.bottom , mArrowPaint);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
int width = getWidth();
int height = getHeight();
mRingCenterRadius = Math.min(width, height);
int result = 10;
int secondRadius = 200;
rectF.set((float) (width / 2 - (secondRadius + result)), (float) (height / 2 - (secondRadius + result)), (float) (width
/ 2 + (secondRadius + result)), (float) (height / 2 + (secondRadius + result)));
centerX = rectF.centerX();
