CancelLoadingThumbnails Method

using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
 
class MyForm : Form 
{ 
   public RasterThumbnailBrowser theBrowser; 
   public bool cancelOperation;        // Informs us if the user canceled the operation 
   public Button buttonCancel;         // Cancel browse loading 
   public Button buttonBrowse;         // Diplays the browse control 
   public ProgressBar progressBar;     // shows progress of loading browse images 
 
   void buttonBrowse_Click(object sender, EventArgs e) 
   { 
      // If we are already loading thumbails, cancel 
      // this operation 
      if (theBrowser.IsLoadingThumbnails) 
         theBrowser.CancelLoadingThumbnails(); 
 
      // Clean all the items 
      theBrowser.Items.Clear(); 
 
      // Update the application state 
      buttonCancel.Enabled = true; 
      progressBar.Value = 0; 
 
      // And load the new thumbnails 
      cancelOperation = false; 
 
      string folderPath = LEAD_VARS.ImagesDir; 
      theBrowser.LoadStamp = true; 
      theBrowser.LoadThumbnails(folderPath, "*.*", RasterThumbnailBrowserLoadFlags.Block); 
 
      theBrowser.Refresh(); 
 
      theBrowser.EnableBrowserWatcher = true; 
   } 
 
   private void thumbnailBrowser_LoadThumbnail(object sender, RasterThumbnailBrowserLoadThumbnailEventArgs e) 
   { 
      // If this is the first iteration, update the progress bar minimum and maximum values 
      if (e.Index == 0) 
      { 
         progressBar.Minimum = 0; 
         progressBar.Maximum = e.Total - 1; 
      } 
 
      // Update where we are in the loading operation 
      progressBar.Value = e.Index; 
 
      // Check if we need to cancel (due to the user clicking the Cancel button) 
      if (cancelOperation) 
         e.Cancel = true; 
   } 
 
   private void thumbnailBrowser_AddFile(object sender, RasterThumbnailBrowserAddFileEventArgs e) 
   { 
      Console.WriteLine("AddFile: {0}    Add: {1}", e.FileName, e.Add); 
   } 
 
   private void thumbnailBrowser_FinishedLoadingThumbnails(object sender, EventArgs e) 
   { 
      buttonCancel.Enabled = false; 
   } 
 
   private void buttonCancel_Click(object sender, EventArgs e) 
   { 
      // The user has clicked the cancel button 
      this.cancelOperation = true; 
   } 
 
   // Create  custom images to use as the "error" and "loading" thumbnails. 
   void CreateErrorThumbnail() 
   { 
      // Get the image size 
      Size imageSize = theBrowser.ItemImageSize; 
 
      // No "loading" thumbnail 
      theBrowser.LoadingThumbnail = null; 
 
      // For the "error" thumbnail, create a red X image 
      RasterColor[] palette = new RasterColor[0]; 
      RasterImage image = new RasterImage( 
         RasterMemoryFlags.Conventional, 
         imageSize.Width, 
         imageSize.Height, 
         24, 
         RasterByteOrder.Bgr, 
         RasterViewPerspective.TopLeft, 
      palette, 
      IntPtr.Zero, 
      0 
      ); 
 
      IntPtr hdc = RasterImagePainter.CreateLeadDC(image); 
      Graphics g = Graphics.FromHdc(hdc); 
 
      g.FillRectangle(Brushes.Magenta, 0, 0, imageSize.Width, imageSize.Height); 
 
      g.DrawLine(Pens.Red, 0, 0, imageSize.Width, imageSize.Height); 
      g.DrawLine(Pens.Red, imageSize.Width, 0, 0, imageSize.Height); 
 
      g.Dispose(); 
      RasterImagePainter.DeleteLeadDC(hdc); 
 
      // Make this image transparent 
      image.Transparent = true; 
      image.TransparentColor = RasterColor.FromKnownColor(RasterKnownColor.Magenta); 
 
      theBrowser.ErrorThumbnail = image; 
   } 
 
   public void Cleanup() 
   { 
      buttonBrowse.Click -= new EventHandler(buttonBrowse_Click); 
      buttonCancel.Click -= new EventHandler(buttonCancel_Click); 
      theBrowser.LoadThumbnail -= new EventHandler<RasterThumbnailBrowserLoadThumbnailEventArgs>(thumbnailBrowser_LoadThumbnail); 
      theBrowser.FinishedLoadingThumbnails -= new EventHandler(thumbnailBrowser_FinishedLoadingThumbnails); 
   } 
 
   public MyForm() 
   { 
      Size = new Size(300, 200); 
 
      // create the browser 
      theBrowser = new RasterThumbnailBrowser(); 
      theBrowser.Codecs = new RasterCodecs(); 
      theBrowser.Dock = DockStyle.Fill; 
      theBrowser.ItemSpacingSize = new Size(10, 10); 
      theBrowser.ThumbnailSizeFlags = RasterSizeFlags.Bicubic; 
      theBrowser.LoadThumbnail += new EventHandler<RasterThumbnailBrowserLoadThumbnailEventArgs>(thumbnailBrowser_LoadThumbnail); 
      theBrowser.FinishedLoadingThumbnails += new EventHandler(thumbnailBrowser_FinishedLoadingThumbnails); 
      theBrowser.AddFile += new EventHandler<RasterThumbnailBrowserAddFileEventArgs>(thumbnailBrowser_AddFile); 
 
      // Create a thumbnail image to be displayed on error 
      CreateErrorThumbnail(); 
 
      // add a panel 
      Panel panel = new Panel(); 
      panel.Dock = DockStyle.Left; 
      panel.Width = 100; 
      Controls.Add(panel); 
      panel.BringToFront(); 
 
      // add a "browse" button 
      buttonBrowse = new Button(); 
      buttonBrowse.Text = "Browse"; 
      buttonBrowse.Dock = DockStyle.Top; 
      panel.Controls.Add(buttonBrowse); 
      buttonBrowse.Click += new EventHandler(buttonBrowse_Click); 
 
      // add a "cancel" button 
      buttonCancel = new Button(); 
      buttonCancel.Text = "Cancel"; 
      buttonBrowse.Dock = DockStyle.Bottom; 
      panel.Controls.Add(buttonCancel); 
      buttonCancel.Click += new EventHandler(buttonCancel_Click); 
 
      // add a progress bar 
      progressBar = new ProgressBar(); 
      progressBar.Dock = DockStyle.Bottom; 
      Controls.Add(progressBar); 
 
      Controls.Add(theBrowser); 
      theBrowser.BringToFront(); 
   } 
 
   private void InitializeComponent() 
   { 
      this.SuspendLayout(); 
      //  
      // MyForm 
      //  
      this.ClientSize = new System.Drawing.Size(315, 273); 
      this.Name = "MyForm"; 
      this.ResumeLayout(false); 
 
   } 
} 
public void RasterThumbnailBrowser_RasterThumbnailBrowser() 
{ 
   MyForm form = new MyForm(); 
   form.ShowDialog(); 
   form.Cleanup(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}