Manina.Windows.Forms.ImageListViewLayoutManager.UpdateGroups C# (CSharp) Method

        private void UpdateGroups()
        {
            if (!mImageListView.showGroups)
                return;

            int x = mItemAreaBounds.Left - mImageListView.ViewOffset.X;
            int y = mItemAreaBounds.Top - mImageListView.ViewOffset.Y;

            if (mImageListView.View == View.Gallery)
            {
                totalWidth = 0;
                totalHeight = mItemAreaBounds.Height;
            }
            else if (mImageListView.View == View.Details)
            {
                totalHeight = 0;
            }
            else
            {
                totalHeight = 0;
                totalWidth = mItemAreaBounds.Width;
            }

            foreach (ImageListView.ImageListViewGroup group in mImageListView.groups)
            {
                if (mImageListView.View == View.Gallery)
                {
                    // Number of rows and columns to enclose all items
                    group.itemRows = mDisplayedRows;
                    group.itemCols = (int)System.Math.Ceiling((float)group.ItemCount / (float)mDisplayedRows);

                    // Header area
                    group.headerBounds = new Rectangle(x, y, cachedGroupHeaderHeight, mItemSize.Height * mDisplayedRows);
                    x += cachedGroupHeaderHeight;

                    // Item area
                    group.itemBounds = new Rectangle(x, y, group.itemCols * mItemSizeWithMargin.Width, group.itemRows * mItemSizeWithMargin.Height);
                    if (group.Collapsed)
                        group.itemBounds.Width = 0;

                    // Update total size
                    totalWidth += group.headerBounds.Width + group.itemBounds.Width;

                    // Offset to next group
                    x += group.itemBounds.Width;
                }
                else
                {
                    // Number of rows and columns to enclose all items
                    group.itemCols = mDisplayedCols;
                    group.itemRows = (int)System.Math.Ceiling((float)group.ItemCount / (float)mDisplayedCols);

                    // Header area
                    group.headerBounds = new Rectangle(x, y, mClientArea.Width + mImageListView.ViewOffset.X, cachedGroupHeaderHeight);
                    y += cachedGroupHeaderHeight;

                    // Item area
                    group.itemBounds = new Rectangle(x, y, group.itemCols * mItemSizeWithMargin.Width, group.itemRows * mItemSizeWithMargin.Height);
                    if (group.Collapsed)
                        group.itemBounds.Height = 0;

                    // Update total size
                    totalHeight += group.headerBounds.Height + group.itemBounds.Height;

                    // Offset to next group
                    y += group.itemBounds.Height;
                }

                group.isVisible = ItemAreaBounds.IntersectsWith(group.headerBounds) || ItemAreaBounds.IntersectsWith(group.itemBounds);
            }

            // Groups processed
            mImageListView.groups.collectionModified = false;
        }