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Draw and Edit Annotations on Documents - WinForms C# .NET 6

This tutorial shows how to use the automated annotation features of the LEADTOOLS SDK in a WinForms C# .NET 6 application using the DocumentViewer control.

Overview
Summary	This tutorial covers automated annotation features in a C# WinForms Application using the Document Viewer.
Completion Time	30 minutes
Visual Studio Project	Download tutorial project (55 KB)
Platform	WinForms C# Application
IDE	Visual Studio 2022
Development License	Download LEADTOOLS

Required Knowledge

Before working on the Draw and Edit Annotations on Documents - WinForms C# tutorial, get familiar with the basic steps of creating a project by reviewing the Add References and Set a License and the Display Files in the Document Viewer tutorials.

Create the Project and Add LEADTOOLS References

Start with a copy of the project created in the Display Files in the Document Viewer tutorial. If the project is not available, follow the steps in that tutorial to create it.

The references needed depend upon the purpose of the project. References can be added by one or the other of the following two methods (but not both). For this project, the following references are needed:

If using NuGet references, this tutorial requires the following NuGet packages and their dependencies:

Leadtools.Annotations.WinForms
Leadtools.Document.Sdk
Leadtools.Document.Viewer.WinForms

If local DLL references are used, the following DLLs are needed. The DLLs are located at <INSTALL_DIR>\LEADTOOLS23\Bin\net:

Leadtools.Annotations.Automation.dll
Leadtools.Annotations.Engine.dll
Leadtools.Annotations.WinForms.dll
Leadtools.Caching.dll
Leadtools.Controls.WinForms.dll
Leadtools.Core.dll
Leadtools.Document.Pdf.dll
Leadtools.Document.Viewer.WinForms.dll
Leadtools.Document.dll
Leadtools.dll

For a complete list of which DLL files are required for your application, refer to Files to be Included in your Application.

Set the License File

The License unlocks the features needed for the project. It must be set before any toolkit function is called. For details, including tutorials for different platforms, refer to the Setting a Runtime License tutorial.

There are two types of runtime licenses:

Evaluation license, obtained at the time the evaluation toolkit is downloaded. It allows the toolkit to be evaluated.
Deployment license. If you need a Deployment license file and developer key, refer to Obtaining a License.

Note: Adding LEADTOOLS NuGet and local references and setting a license are covered in more detail in the Add References and Set a License tutorial.

Add the Annotations Toolbar Panel

With the project created, the references added, the license set, and the Document Viewer code added, coding can begin.

Go to Form1.cs in the Solution Explorer. Right-click on the Design Window and select View Code or press F7 to bring up the code behind the Form.

Add the following statements to the using block at the top:

using Leadtools; 
using Leadtools.Document; 
using Leadtools.Caching; 
using Leadtools.Document.Viewer; 
using Leadtools.Controls; 
using Leadtools.Annotations.Automation; 
using Leadtools.Annotations.WinForms;

Add the code below to the InitUI() method to create the panel that will hold the annotations toolbar:

var annToolbarPanel = new Panel(); 
annToolbarPanel.Name = "annToolBarPanel"; 
annToolbarPanel.Width = 200; 
annToolbarPanel.Dock = DockStyle.Right; 
annToolbarPanel.BackColor = Color.LightBlue; 
annToolbarPanel.BorderStyle = BorderStyle.FixedSingle; 
this.Controls.Add(annToolbarPanel);

Modify the DocumentViewer to use Annotations

In the InitDocumentViewer() method, change createOptions.UseAnnotations value to true and add a call to InitAnnotations() method.

var createOptions = new DocumentViewerCreateOptions(); 
// Set the UI part where the Document Viewer is displayed  
createOptions.ViewContainer = this.Controls.Find("docViewerPanel", false)[0]; 
// Set the UI part where the Thumbnails are displayed  
createOptions.ThumbnailsContainer = this.Controls.Find("thumbPanel", false)[0]; 
// Enable using annotations 
createOptions.UseAnnotations = true; 
 
// Now create the viewer  
_documentViewer = DocumentViewerFactory.CreateDocumentViewer(createOptions); 
// Initialize Annotations 
InitAnnotations();

Add the Automation Annotation Code

Use the code below for the InitAnnotations() method, to initialize the automation manager, create and populate the toolbar, and enable a context menu to show when right-clicking an annotation in the Document Viewer.

private void InitAnnotations() 
{ 
   // The annotations toolbar will be added here  
   var annToolbarPanel = this.Controls.Find("annToolBarPanel", true)[0]; 
 
   // Get the automation manager from the document viewer 
   var automationManager = _documentViewer.Annotations.AutomationManager; 
   // Create the manager helper. This sets the rendering engine 
   var automationManagerHelper = new AutomationManagerHelper(automationManager); 
   // Tell the document viewer that automation manager helper is created 
   _documentViewer.Annotations.Initialize(); 
 
   // Create the toolbar  
   automationManagerHelper.ModifyToolBarParentVisiblity = true; 
   automationManagerHelper.CreateToolBar(); 
   var annToolBar = automationManagerHelper.ToolBar; 
   annToolBar.Dock = DockStyle.Fill; 
   annToolBar.AutoSize = true; 
   annToolBar.LayoutStyle = ToolStripLayoutStyle.Flow; 
   annToolbarPanel.Controls.Add(annToolBar); 
   annToolBar.BringToFront(); 
 
   // Handler for showing the context menu when the user right-clicks on an annotation object  
   EventHandler<AnnAutomationEventArgs> onShowContextMenu = (sender, e) => 
   { 
      // If not clicked on an annotation object 
      if (e == null) 
         return; 
 
      // Get the object type  
      var automationObject = e.Object as AnnAutomationObject; 
      if (automationObject == null) 
         return; 
 
      // Convert the point to client coordinates  
      var imageViewer = _documentViewer.View.ImageViewer; 
      var position = imageViewer.PointToClient(Cursor.Position); 
      var automation = _documentViewer.Annotations.Automation; 
 
      // Show its context menu  
      var contextMenu = automationObject.ContextMenu as ObjectContextMenu; 
      if (contextMenu != null) 
      { 
         contextMenu.Automation = automation; 
         contextMenu.Show(imageViewer, position); 
      } 
   }; 
 
   // Handler for showing the object properties dialog  
   EventHandler<AnnAutomationEventArgs> onShowObjectProperties = (sender, e) => 
   { 
      // Get the automation object from the document viewer  
      using (var dlg = new AutomationUpdateObjectDialog()) 
      { 
         dlg.UserName = _documentViewer.UserName; 
         dlg.Automation = sender as AnnAutomation; 
         dlg.ShowDialog(this); 
         e.Cancel = !dlg.IsModified; 
      } 
   }; 
 
   // Handle extra annotations using the Operation event  
   _documentViewer.Operation += (sender, e) => 
   { 
      switch (e.Operation) 
      { 
         case DocumentViewerOperation.LoadingAnnotations: 
            // Disable the panel containing the toolbar when loading it, then enable it when done  
            annToolbarPanel.Enabled = e.IsPostOperation; 
            break; 
 
         case DocumentViewerOperation.CreateAutomation: 
            if (e.IsPostOperation) 
            { 
               // Automation object has been created, use it to perform any extra task not handled by the  
               // document viewer by default  
               // Handle showing the context menu when the user right-clicks on an object and when they  
               // select properties  
               _documentViewer.Annotations.Automation.OnShowContextMenu += onShowContextMenu; 
               _documentViewer.Annotations.Automation.OnShowObjectProperties += onShowObjectProperties; 
            } 
            break; 
 
         case DocumentViewerOperation.DestroyAutomation: 
            if (!e.IsPostOperation) 
            { 
               // Automation is about to be destroyed, remove any events we used  
               _documentViewer.Annotations.Automation.OnShowContextMenu -= onShowContextMenu; 
               _documentViewer.Annotations.Automation.OnShowObjectProperties -= onShowObjectProperties; 
            } 
            break; 
 
         default: 
            break; 
      } 
   }; 
}

Run the Project

Run the project by pressing F5, or by selecting Debug -> Start Debugging.

If the steps were followed correctly, the application runs and any of the annotations on the toolbar can be selected to draw on the loaded document. The following image shows the Document Viewer, with the annotation toolbar on the right of the viewer.

DocumentViewer showing some annotations drawn on an Document

Wrap-up

This tutorial showed how to use the AutomationManager, AutomationManagerHelper and AnnAutomation classes with the DocumentViewer control to draw and edit automated annotations.