- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {

    if (![kind isEqualToString:[myGridHeaderView kind]]) {
        return nil;
    }

    myGridHeaderPosition headerPosition = [[self collectionView] headerPositionAtIndexPath:indexPath];
    CGRect cellRect = [[self delegate] getRectForHeaderAtIndex:indexPath headerPosition:headerPosition];

    if (CGRectEqualToRect(cellRect, CGRectZero)) {
        return nil;
    }

    myGridHeaderLayoutAttribute* attributes = [myGridHeaderLayoutAttribute layoutAttributesForSupplementaryViewOfKind:kind withIndexPath:indexPath];

    CGPoint centerPoint = CGPointMake(CGRectGetMidX(cellRect), CGRectGetMidY(cellRect));
    CGSize  size        = cellRect.size;


    UICollectionView * const cv = self.collectionView;

    NSInteger zIndex = 1;
    CGPoint const contentOffset = cv.contentOffset;

    if (contentOffset.x > 0)
    {
        if (headerPosition != myGridHeaderPositionColumn)
        {
            centerPoint.x += contentOffset.x;
        }
        zIndex = 1005;
    }
    if (contentOffset.y > 0)
    {
        if (headerPosition != myGridHeaderPositionRow)
        {
            centerPoint.y += contentOffset.y;
        }
        zIndex = 1005;
    }
    if (headerPosition == myGridHeaderPositionCommon) {
        zIndex = 1024;
    }
    attributes.zIndex = zIndex;
    attributes.headerPosition = headerPosition;
    attributes.center = centerPoint;
    attributes.size = size;
    attributes.alpha = 1.0;

    return attributes;

}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    isScrollingStart=YES;
    NSLog(@"scrollViewDidScroll  %f , %f",scrollView.contentOffset.x,scrollView.contentOffset.y);


    if (scrollView.contentOffset.y<=124) {
        _img_top_header.alpha=scrollView.contentOffset.y/124;
    }
    else
    {
        _img_top_header.alpha=1.0;
    }



}