BeginUpdate Method (RasterThumbnailBrowser)

using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
 
class MyForm2 : Form 
{ 
   RasterImageViewer viewer; 
   RasterImageList imageList; 
   RasterCodecs codecs; 
 
   public MyForm2() 
   { 
      // Set the size of the form 
      Size = new Size(400, 200); 
 
      // Create a new RasterImageList control 
      imageList = new RasterImageList(); 
      imageList.Dock = DockStyle.Left; 
      imageList.SelectionMode = RasterImageListSelectionMode.Single; 
      Controls.Add(imageList); 
      imageList.BringToFront(); 
 
      // Add a handler to the SelectedIndexChanged event 
      imageList.SelectedIndexChanged += new EventHandler(rasterImageList_SelectedIndexChanged); 
 
      Splitter splitter = new Splitter(); 
      splitter.Dock = DockStyle.Left; 
      Controls.Add(splitter); 
      splitter.BringToFront(); 
 
      viewer = new RasterImageViewer(); 
      viewer.Dock = DockStyle.Fill; 
      Controls.Add(viewer); 
      viewer.BringToFront(); 
 
      // Now load all our images 
      codecs = new RasterCodecs(); 
 
      string folderName = LEAD_VARS.ImagesDir; 
      string[] files = Directory.GetFiles(folderName, "*.*"); 
 
      // This is going to be a lengthy operation 
      // Suspend painting the RasterImageList 
      imageList.BeginUpdate(); 
 
      foreach (string fileName in files) 
      { 
         // Load the image as a thumbnail 
         RasterImage image = LoadThumbnail(fileName); 
 
         // Only add an item if we loaded the image successfuly 
         if (image != null) 
         { 
            // Create an item 
            RasterImageListItem item = new RasterImageListItem(); 
 
 
            // Setup the item information 
            item.Image = image; 
            item.Text = Path.GetFileName(fileName); 
            item.Page = 1; 
 
            // To load this image in original size later 
            item.FileName = fileName; 
 
            // Add the item into RasterImageList 
            imageList.Items.Add(item); 
         } 
      } 
 
      imageList.EndUpdate(); 
 
   } 
 
   private void rasterImageList_SelectedIndexChanged(object sender, EventArgs e) 
   { 
      // User has selected an item from the RasterImageList control. 
      // Re-load the item image and show it in original size in the viewer 
 
      // Get the selected item(s) 
      RasterImageListItemCollection selectedItems = imageList.SelectedItems; 
      if (selectedItems != null && selectedItems.Count == 1) 
      { 
         RasterImageListItem item = selectedItems[0]; 
 
         // Load the image in its original size and set it in the viewer 
         viewer.Image = codecs.Load( 
            item.FileName, 
            0, 
            CodecsLoadByteOrder.BgrOrGray, 
            1, 
            1); 
      } 
   } 
 
   private RasterImage LoadThumbnail(string fileName) 
   { 
      RasterImage image = null; 
 
      try 
      { 
         // See if we can load this image 
         CodecsImageInfo info = codecs.GetInformation(fileName, false, 1); 
 
         if (info.Format != RasterImageFormat.Unknown) 
         { 
            // Yes, calculate the thumbnail size to fit into RasterImageList.ItemImageSize 
            Rectangle rc = new Rectangle( 
               0, 
               0, 
               imageList.ItemImageSize.Width, 
               imageList.ItemImageSize.Height); 
 
            rc = RasterImageList.GetFixedAspectRatioImageRectangle(info.Width, info.Height, rc); 
 
            // Load the thumbnail 
            image = codecs.Load( 
               fileName, 
               rc.Width, 
               rc.Height, 
               24, 
               RasterSizeFlags.Resample, 
               CodecsLoadByteOrder.BgrOrGray, 
               1, 
               1); 
         } 
         else 
            image = null; 
      } 
      catch 
      { 
         image = null; 
      } 
      return image; 
   } 
} 
 
public void RasterImageList_Image() 
{ 
   MyForm2 form = new MyForm2(); 
   form.ShowDialog(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}