public DefaultCellCalculator(int showCnt){
        mCnt = showCnt;
        mCells = new Cell[mCnt];
        mAlphas = new float[mCnt];
        STATIC_ALPHA = new int[mCnt];
        STATIC_ALPHA[mCnt - 1] = 0; //最后一张图的透明度为0
        int alphaUnit = (255 - FIRST_ALPHA) / (mCnt - 2);
        for(int i = mCnt - 2; i >= 0; i--){  //定义静态时每张图的透明度
            STATIC_ALPHA[i] = FIRST_ALPHA + (mCnt - 2 - i) * alphaUnit;
        }
    }

    @Override
    public Cell[] getCells() {
        return  mCells;
    }
    
    //用户手势移动，distance表示移动距离，正负值分别意味着需要向前/向后移动
    @Override
    public int setStatus(float distance) {
        if(distance > 0){
            return calculateForward(distance);
        } else if(distance < 0){
            return calculateBackward(distance);
        } else{
            initCells();
        }
        return 0;
    }

    //