BExplorer.Shell.ShellView.RetrieveThumbnailByIndex C# (CSharp) Method

    private async void RetrieveThumbnailByIndex(Int32 index) {
      await Task.Run(() => {
        if (this.IsCancelRequested) return;

        //F.Application.DoEvents();
        var itemBounds = new User32.RECT();
        var lvi = new LVITEMINDEX() { iItem = index, iGroup = this.GetGroupIndex(index) };
        User32.SendMessage(this.LVHandle, MSG.LVM_GETITEMINDEXRECT, ref lvi, ref itemBounds);

        var r = new Rectangle(itemBounds.Left, itemBounds.Top, itemBounds.Right - itemBounds.Left, itemBounds.Bottom - itemBounds.Top);

        if (r.IntersectsWith(this.ClientRectangle)) {
          var sho = Items[index];
          var icon = sho.GetHBitmap(IconSize, true, true);
          sho.IsThumbnailLoaded = true;
          sho.IsNeedRefreshing = false;
          if (icon != IntPtr.Zero) {
            Int32 width = 0, height = 0;
            Gdi32.ConvertPixelByPixel(icon, out width, out height);
            sho.IsOnlyLowQuality = (width > height && width != IconSize) || (width < height && height != IconSize) || (width == height && width != IconSize);
            Gdi32.DeleteObject(icon);
            this.RedrawItem(index);
          }
        }
      });
    }