ondraw绘制顺序调整建议，目前先绘制item后绘制Curtain，drawIndicator会导致选中项被遮盖颜色值变浅

@Override
protected void onDraw(Canvas canvas) {
if (null != onWheelChangedListener) {
onWheelChangedListener.onWheelScrolled(this, scrollOffsetYCoordinate);
}
if (itemHeight - halfDrawnItemCount <= 0) {
return;
}
drawAllItem(canvas);
drawCurtain(canvas);
drawIndicator(canvas);
}

调整为
@Override
protected void onDraw(Canvas canvas) {
if (null != onWheelChangedListener) {
onWheelChangedListener.onWheelScrolled(this, scrollOffsetYCoordinate);
}
if (itemHeight - halfDrawnItemCount <= 0) {
return;
}
drawCurtain(canvas);
drawIndicator(canvas);
drawAllItem(canvas);
}