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Custom Annotations

It is possible to create Custom Annotations by implementing IAnnotation or inheriting Annotation. Once a custom annotation has been created, instances of these custom annotations can be added to the chart’s Annotations collection.

Note
Note

Note : For an example procedure on how to create chart annotations, see Create Annotations.
A Column Chart with a Smiley face that was created using Custom Annotations.

In Visual Basic:

Me.UltraChart1.Annotations.Add(New MyAnnotation())

In C#:

this.ultraChart1.Annotations.Add(new MyAnnotation());

The IAnnotation interface consists of one property, Location. When implementing the interface, it is sufficient to simply store this property in a private field within the class.

The important part of the IAnnotation interface is the RenderAnnotation method. There are two overloads for this method; one takes a Primitive object which represents the "parent" primitive, and the other overload takes a Point which represents the point the Annotation is to be rendered at.

These different overloads exists because of the different ways of matching an annotation to the chart using a Location object. In cases where row and/or column wildcards are used, this method may be called more than one time per annotation per chart.

For the overload of RenderAnnotation with a "parent" Primitive as a parameter, the static Annotation. GetRenderPointFromParent method is provided as an easy way to get a render point from the parent primitive. Further customization of an Annotation class would probably require custom code to get an appropriate point based on a parent Primitive . From this point, the other overload of RenderAnnotation can be called; of course this is not a requirement, just a programming guideline.

Code to draw annotations is just like code that goes in a custom layer’s FillSceneGraph method: Primitives must be created and added to the SceneGraph.

Following is an example of a simple, but complete, custom Annotation class:

In Visual Basic:

Imports System
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports Infragistics.UltraChart.Core
Imports Infragistics.UltraChart.Core.Primitives
Imports Infragistics.UltraChart.Resources.Appearance
Imports Infragistics.UltraChart.Shared.Styles
Public Class MyAnnotation
  Implements IAnnotation
	Public Sub RenderAnnotation(ByVal scene As SceneGraph, _
	  ByVal renderPoint As Point) Implements IAnnotation.RenderAnnotation
		Dim head As New Ellipse(renderPoint, 50)
		head.PE.Fill = Color.Yellow
		head.PE.StrokeWidth = 5
		scene.Add(head)
		Dim mouth As New Wedge(renderPoint, 40, 0, 180)
		mouth.PE.Fill = Color.Black
		mouth.PE.FillStopColor = Color.White
		mouth.PE.ElementType = PaintElementType.Hatch
		mouth.PE.Hatch = FillHatchStyle.Vertical
		mouth.PE.StrokeWidth = 3
		scene.Add(mouth)
		Dim leftEye As New Ellipse(New Point(renderPoint.X - 20, renderPoint.Y - 20), 5)
		Dim rightEye As New Ellipse(New Point(renderPoint.X + 20, renderPoint.Y - 20), 5)
		leftEye.PE.Fill = Color.Black
		rightEye.PE.Fill = Color.Black
		scene.Add(leftEye)
		scene.Add(rightEye)
	End Sub
	Public Sub RenderAnnotation(ByVal scene As SceneGraph, _
	  ByVal parent As Primitive) Implements IAnnotation.RenderAnnotation
		Dim renderPoint As Point = Annotation.GetRenderPointFromParent(parent)
		Me.RenderAnnotation(scene, renderPoint)
	End Sub
	Private _location As New Location()
	Public Property Location() As Location Implements IAnnotation.Location
		Get
			Return Me._location
		End Get
		Set(ByVal Value As Location)
			Me._location = Value
		End Set
	End Property
End Class

In C#:

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using Infragistics.UltraChart.Core;
using Infragistics.UltraChart.Core.Primitives;
using Infragistics.UltraChart.Resources.Appearance;
using Infragistics.UltraChart.Shared.Styles;
public class MyAnnotation : IAnnotation
{
	public void RenderAnnotation(SceneGraph scene, Point renderPoint)
	{
		Ellipse head = new Ellipse(renderPoint, 50);
		head.PE.Fill = Color.Yellow;
		head.PE.StrokeWidth = 5;
		scene.Add(head);
		Wedge mouth = new Wedge(renderPoint, 40, 0, 180);
		mouth.PE.Fill = Color.Black;
		mouth.PE.FillStopColor = Color.White;
		mouth.PE.ElementType = PaintElementType.Hatch;
		mouth.PE.Hatch = FillHatchStyle.Vertical;
		mouth.PE.StrokeWidth = 3;
		scene.Add(mouth);
		Ellipse leftEye  =
		  new Ellipse(new Point(renderPoint.X - 20, renderPoint.Y - 20), 5);
		Ellipse rightEye =
		  new Ellipse(new Point(renderPoint.X + 20, renderPoint.Y - 20), 5);
		leftEye.PE.Fill  = Color.Black;
		rightEye.PE.Fill = Color.Black;
		scene.Add(leftEye);
		scene.Add(rightEye);
	}
	public void RenderAnnotation(SceneGraph scene, Primitive parent)
	{
		Point renderPoint = Annotation.GetRenderPointFromParent(parent);
		this.RenderAnnotation(scene, renderPoint);
	}
	private Location _location = new Location();
	public Location Location
	{
		get
		{
			return this._location;
		}
		set
		{
			this._location = value;
		}
	}
}