怎么让字体大小不是固定的normalTextsize 和 selectedSize ，而是随着远离中心逐渐变小，接近中心逐渐变大？ about numberpickerview HOT 3 CLOSED

if(i == mShowCount / 2){//this will be picked
                fraction = (float)(mItemHeight + mCurrDrawFirstItemY) / mItemHeight;
                textColor = getEvaluateColor(fraction, mTextColorNormal, mTextColorSelected);
                textSize = getEvaluateSize(fraction, mTextSizeNormal, mTextSizeSelected);
                textSizeCenterYOffset = getEvaluateSize(fraction, mTextSizeNormalCenterYOffset,
                        mTextSizeSelectedCenterYOffset);
            }else if(i == mShowCount / 2 + 1){
                textColor = getEvaluateColor(1 - fraction, mTextColorNormal, mTextColorSelected);
                textSize = getEvaluateSize(1 - fraction, mTextSizeNormal, mTextSizeSelected);
                textSizeCenterYOffset = getEvaluateSize(1 - fraction, mTextSizeNormalCenterYOffset,
                        mTextSizeSelectedCenterYOffset);
            }else{
                textColor = mTextColorNormal;
                textSize = mTextSizeNormal;
                textSizeCenterYOffset = mTextSizeNormalCenterYOffset;
            }