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Thumbnails Property

Summary

Manages the thumbnails in this document viewer.

Syntax
C#
C++/CLI
public DocumentViewerThumbnails Thumbnails { get; } 
public:  
   property DocumentViewerThumbnails^ Thumbnails 
   { 
      DocumentViewerThumbnails^ get() 
   } 

Property Value

The DocumentViewerThumbnails object that manages the thumbnails in this document viewer.

Remarks

This class manages the thumbnail image of the pages in the current LEADDocument set in the document viewer.

The class creates an instance of ImageViewer for viewing the thumbnails. The thumbnail images are loaded in a background thread to keep the application user interface responsive.

The class also handles the user interactions with the thumbnails, such as clicking on a thumbnail to move the view to the specified page.

When the Document Viewer is created

Refer to DocumentViewerThumbnails for more information.

Example
C#
using Leadtools; 
using Leadtools.Controls; 
using Leadtools.Document; 
using Leadtools.Document.Viewer; 
using Leadtools.Codecs; 
using Leadtools.Caching; 
using Leadtools.Annotations.Engine; 
using Leadtools.Ocr; 
 
 
public void DocumentViewer_Example() 
{ 
   // New Form to be used as our application 
   var form = new MyForm(); 
   form.ShowDialog(); 
} 
 
class MyForm : Form 
{ 
   public MyForm() 
   { 
      this.Size = new Size(800, 800); 
      this.Text = "LEADTOOLS Document Viewer Example"; 
   } 
 
   protected override void OnLoad(EventArgs e) 
   { 
      if (!DesignMode) 
      { 
         // Init OCR. This is optional and not required for the PDF document we are loading. 
         // But if image documents are loaded and text functionality is used, then we need OCR 
         _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD); 
         _ocrEngine.Startup(null, null, null, @"C:\LEADTOOLS22\Bin\Common\OcrLEADRuntime"); 
 
         Init(); 
      } 
 
      base.OnLoad(e); 
   } 
 
   // Our document viewer instance 
   private DocumentViewer _documentViewer; 
 
   // Optional OCR engine to use in the example 
   private IOcrEngine _ocrEngine; 
 
   private void Init() 
   { 
      // Initialize the user interface 
      InitUI(); 
 
      // Init the cache. This is optional, but it can speed up viewing of large documents 
      // if not needed, remove this section 
      DocumentFactory.Cache = new FileCache(); 
 
      // Init the document viewer, pass along the panels 
      var createOptions = new DocumentViewerCreateOptions 
      { 
         // The middle panel for the view 
         ViewContainer = this.Controls.Find("middlePanel", false)[0], 
         // The left panel for the thumbnails 
         ThumbnailsContainer = this.Controls.Find("leftPanel", false)[0], 
         // The right panel is for bookmarks 
         BookmarksContainer = this.Controls.Find("rightPanel", false)[0], 
         // Not using annotations for now 
         UseAnnotations = false 
      }; 
 
      // Create the document viewer 
      _documentViewer = DocumentViewerFactory.CreateDocumentViewer(createOptions); 
 
      // We prefer SVG viewing 
      _documentViewer.View.PreferredItemType = DocumentViewerItemType.Svg; 
 
      // Load a document 
      var fileName = @"C:\LEADTOOLS22\Resources\Images\Leadtools.pdf"; 
      var document = DocumentFactory.LoadFromFile( 
         fileName, 
         new LoadDocumentOptions { UseCache = DocumentFactory.Cache != null }); 
 
      _documentViewer.Operation += (sender, e) => 
      { 
         if (e.Operation == DocumentViewerOperation.LoadingBookmarks) 
         { 
            // Disable the bookmarks when we are loading, enable when we are done 
            var rightPanel = this.Controls.Find("rightPanel", true)[0]; 
            if (rightPanel.InvokeRequired) 
            { 
               rightPanel.Invoke((MethodInvoker)delegate { rightPanel.Enabled = e.IsPostOperation; }); 
            } 
            else 
            { 
               rightPanel.Enabled = e.IsPostOperation; 
            } 
         } 
      }; 
 
      // If we have an OCR engine, use it 
      document.Text.OcrEngine = _ocrEngine; 
 
      // Set it in the viewer 
      _documentViewer.SetDocument(document); 
 
      // Run pan/zoom 
      var interactiveComboBox = this.Controls.Find("interactiveComboBox", true)[0] as ComboBox; 
      interactiveComboBox.SelectedItem = DocumentViewerCommands.InteractivePanZoom; 
   } 
 
   private void InitUI() 
   { 
      // Add a panel on the left for the document viewer thumbnails part 
      var leftPanel = new Panel(); 
      leftPanel.Name = "leftPanel"; 
      leftPanel.Width = 200; 
      leftPanel.Dock = DockStyle.Left; 
      leftPanel.BackColor = Color.Gray; 
      leftPanel.BorderStyle = BorderStyle.FixedSingle; 
      this.Controls.Add(leftPanel); 
 
      // Add a panel to the right, this will work for the bookmarks or annotations part 
      var rightPanel = new Panel(); 
      rightPanel.Name = "rightPanel"; 
      rightPanel.Width = 200; 
      rightPanel.Dock = DockStyle.Right; 
      rightPanel.BackColor = Color.LightBlue; 
      rightPanel.BorderStyle = BorderStyle.FixedSingle; 
      this.Controls.Add(rightPanel); 
 
      // Add a panel to fill the rest, for the document viewer 
      var middlePanel = new Panel(); 
      middlePanel.Name = "middlePanel"; 
      middlePanel.BackColor = Color.DarkGray; 
      middlePanel.BorderStyle = BorderStyle.None; 
      middlePanel.Dock = DockStyle.Fill; 
      this.Controls.Add(middlePanel); 
 
      // Add a top panel to host our application controls 
      var topPanel = new Panel(); 
      topPanel.Name = "topPanel"; 
      topPanel.Height = 100; 
      topPanel.Dock = DockStyle.Top; 
      topPanel.BorderStyle = BorderStyle.FixedSingle; 
      this.Controls.Add(topPanel); 
 
      middlePanel.BringToFront(); 
 
      // Add buttons for the UI 
 
      // Combo box for interactive modes 
      var interactiveComboBox = new ComboBox(); 
      interactiveComboBox.Name = "interactiveComboBox"; 
      interactiveComboBox.DropDownStyle = ComboBoxStyle.DropDownList; 
      // The command names for the items so we can just run them 
      interactiveComboBox.Items.Add(DocumentViewerCommands.InteractivePanZoom); 
      interactiveComboBox.Items.Add(DocumentViewerCommands.InteractiveSelectText); 
      interactiveComboBox.SelectedIndexChanged += (sender, e) => 
      { 
         var commandName = interactiveComboBox.SelectedItem as string; 
         _documentViewer.Commands.Run(commandName); 
      }; 
      topPanel.Controls.Add(interactiveComboBox); 
 
      // Generic label for information used by the examples 
      var infoLabel = new Label(); 
      infoLabel.Name = "infoLabel"; 
      infoLabel.Text = "Info..."; 
      infoLabel.AutoSize = false; 
      infoLabel.Width = 400; 
      infoLabel.Left = interactiveComboBox.Right + 20; 
      topPanel.Controls.Add(infoLabel); 
 
      var exampleButton = new Button(); 
      exampleButton.Top = interactiveComboBox.Bottom + 2; 
      exampleButton.Name = "exampleButton"; 
      exampleButton.Text = "&Example"; 
      exampleButton.Click += (sender, e) => Example(exampleButton); 
      topPanel.Controls.Add(exampleButton); 
   } 
 
   private void Example(Button exampleButton) 
   { 
      // Add the example code here 
      Console.WriteLine(this + " Ready"); 
   } 
} 
Requirements

Target Platforms

Help Version 22.0.2023.1.30
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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Document.Viewer.WinForms Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.