public void fillAlphaData(BaseDanmaku item, int beginAlpha, int endAlpha,
                              long alphaDuraion) {
        if (item.getType() != BaseDanmaku.TYPE_SPECIAL)
            return;
        ((SpecialDanmaku) item).setAlphaData(beginAlpha, endAlpha, alphaDuraion);
        updateSpecicalDanmakuDuration(item);
    }
Initial alpha data of the special danmaku

@param item
@param beginAlpha
@param endAlpha
@param alphaDuraion
app/src/main/java/com/sunnyweather/android/flame/master/flame/danmaku/danmaku/model/android/DanmakuFactory.java