Implementing User-Defined Objects with LEADTOOLS Annotations in Windows Forms

Start with the project created in Draw and Edit Annotations on Images.

The object being created is a simple triangle. This object will have three points for the end points of the triangle and it will use a stroke for the triangle edges and a fill for the interior.

Add a new C# class to your project and add the following code:

// The Triangle annotation object 
public class AnnTriangleObject : AnnPolylineObject 
{ 
   // The object ID, let us select a user defined value 
   public const int MyId = AnnObject.UserObjectId; 
                  
   public AnnTriangleObject() : 
      base() 
   { 
      // Set an ID 
      SetId(MyId); 
                  
      // We are a closed-figure 
      IsClosed = true; 
   } 
                  
   // Our friendly name 
   public override string FriendlyName 
   { 
      get 
      { 
         return "Triangle"; 
      } 
   } 
}

Since there are is no existing draw designer that can be used with our AnnTriangleObject class, we need to create our own:

// Our draw designer 
public class AnnTriangleDrawDesigner : AnnDrawDesigner 
{ 
   public AnnTriangleDrawDesigner(IAnnAutomationControl automationControl, AnnContainer container, AnnObject annObject) : 
      base(automationControl, container, annObject) 
   { 
   } 
                  
   // Override the Pointer Down event and add 3 points for our triangle 
   public override bool OnPointerDown(AnnContainer sender, AnnPointerEventArgs e) 
   { 
      // See if the base class wants to handle the event 
      bool handled = base.OnPointerDown(sender, e); 
      if (handled) 
         return true; 
                  
      // We will work on left button only 
      if (e.Button != AnnMouseButton.Left) 
         return false; 
                  
      // Get the current number of points in the object 
      AnnObject annObject = this.TargetObject; 
      int pointCount = annObject.Points.Count; 
                  
      if (pointCount < 3) 
      { 
         // Add the current point 
         annObject.Points.Add(e.Location); 
                 
        // If we had 0 points, then add another one. When we move the pointer, we will 
        // move the last point (second in this case) 
        if (pointCount == 0) 
           annObject.Points.Add(e.Location); 
                 
        if (pointCount == 0) 
        { 
           if (!this.StartWorking()) 
              return true; 
        } 
     } 
     else 
     { 
        // We have 3 points, we are finished 
        this.EndWorking(); 
     } 
                 
     return true; 
  } 
                 
  // Override the Pointer Move event 
  public override bool OnPointerMove(AnnContainer sender, AnnPointerEventArgs e) 
  { 
     bool handled = base.OnPointerMove(sender, e); 
                 
     // See if we have points 
     // If so, move the last point in the object to this new location 
     AnnObject annObject = this.TargetObject; 
                 
     if (annObject.Points.Count > 0) 
     { 
        annObject.Points[annObject.Points.Count - 1] = e.Location; 
        Working(); 
        return true; 
     } 
                 
     return false; 
  } 
                 
  public override bool OnPointerUp(AnnContainer sender, AnnPointerEventArgs e) 
  { 
     base.OnPointerUp(sender, e); 
     return true; 
  } 
}

Next, we need to add the automation object for the Triangle:

private static void InitializeTriangleObject(AnnAutomationManagerHelper annotations) 
{ 
   // Create a new automation object 
   AnnAutomationObject automationObj = new AnnAutomationObject(); 
                  
   // Set the object ID 
   automationObj.Id = AnnTriangleObject.MyId; 
   automationObj.Name = "Triangle"; 
    
   // Set its designers 
   automationObj.DrawDesignerType = typeof(AnnTriangleDrawDesigner); 
   automationObj.EditDesignerType = typeof(AnnPolylineEditDesigner); 
   automationObj.RunDesignerType = typeof(AnnRunDesigner); 
                  
   // Set the template 
   AnnTriangleObject annObj = new AnnTriangleObject(); 
    
   // Set our default stroke 
   annObj.Stroke = AnnStroke.Create(AnnSolidColorBrush.Create("red"), LeadLengthD.Create(2)); 
   annObj.Fill = AnnSolidColorBrush.Create("yellow"); 
   automationObj.ObjectTemplate = annObj; 
                  
   // Set our renderer, same as the AnnPolylineObject 
   IAnnObjectRenderer polylineRenderer = annotations.AutomationManager.RenderingEngine.Renderers[AnnObject.PolylineObjectId]; 
   IAnnObjectRenderer renderer = new AnnPolylineObjectRenderer(); 
   renderer.LabelRenderer = polylineRenderer.LabelRenderer; 
   renderer.LocationsThumbStyle = polylineRenderer.LocationsThumbStyle; 
   renderer.RotateGripperThumbStyle = polylineRenderer.RotateGripperThumbStyle; 
   renderer.RotateCenterThumbStyle = polylineRenderer.RotateCenterThumbStyle; 
   annotations.AutomationManager.RenderingEngine.Renderers[AnnTriangleObject.MyId] = renderer; 
                  
   // Set its context menu and toolbar image                  
   AnnAutomationObjectExtData extData = new AnnAutomationObjectExtData(); 
   extData.ContextMenu = new Leadtools.Annotations.WinForms.ObjectContextMenu(); 
   extData.DrawCursor = Cursors.Cross; 
                  
   Bitmap bitmap = new Bitmap(24, 24, System.Drawing.Imaging.PixelFormat.Format32bppArgb); 
   using (Graphics g = Graphics.FromImage(bitmap)) 
   { 
      g.Clear(Color.Transparent); 
      g.DrawLine(Pens.Black, 12, 2, 22, 22); 
      g.DrawLine(Pens.Black, 22, 22, 2, 22); 
      g.DrawLine(Pens.Black, 2, 22, 12, 2); 
   } 
                  
   extData.ToolBarImage = bitmap; 
   extData.ToolBarToolTipText = "Triangle"; 
                  
   automationObj.UserData = extData; 
                  
   annotations.AutomationManager.Objects.Add(automationObj); 
}

And finally, modify the original code like this:

// Create the helper 
_annotations = new AnnAutomationManagerHelper(automationManager); 
                  
// -------------------------- 
// Create our triangle automation object 
InitializeTriangleObject(_annotations); 
// -------------------------- 
                  
// Create the toolbar and add it to our form 
_annotations.CreateToolBar(); 
ToolBar toolBar = _annotations.ToolBar;

Build and run the demo. Now you can click the triangle toolbar icon and draw an instance of the new object.

Implementing User-Defined Objects with LEADTOOLS Annotations in Windows Forms

See Also