Event Handlers in Windows Forms Diagram

27 Apr 202124 minutes to read

This section elaborates on the following:

Diagram Events

DiagramViewerEventSink class contains the events specific to the diagram. The various events that can be invoked using this class are discussed in the following topics.

Node Collection Events

This topic discusses the events that are fired while adding or removing the node to or from the node collection. The below table discusses all the available node collection events.

Node Collection Events

DiagramViewerEventSink	Description
NodeCollectionChanged	Triggered after the node collection changes are completed.
NodeCollectionChanging	Triggered when the node collection is edited.

EventArgs members can be accessed using the following members.

Properties

NodeCollection EventArgs Member	Description
Cancel	Indicates whether the NodeCollectionChanged event should be canceled.
ChangeType	It returns the following possible values:Insert - whether the node is insertedRemove – whether the node is removed
Element	Returns whether the head or tail end is moved.
Elements	Returns the elements collection on which the event occurs.
Index	Returns the zero-based index into the collection on which the event occurred.
Owner	Returns the base class onto which the node is added.

Inside the NodeCollectionChanged event handler, user can identify whether a node is added or removed from the node collection using simple message box as follows.

C#

private void Form1_Load(object sender, EventArgs e)
{
	((DiagramViewerEventSink)diagram1.EventSink).NodeCollectionChanged += new CollectionExEventHandler(Form1_NodeCollectionChanged)((DiagramViewerEventSink)diagram1.EventSink).NodeCollectionChanging += new CollectionExEventHandler(Form1_NodeCollectionChanging);
	RectangleF rect = new RectangleF(100, 100, 100, 100);
	RichTextNode richText = new RichTextNode("", rect);
	richText.Text = "Rich text box";
	NodeCollection nodeStack = new NodeCollection();
	nodeStack.Add(richText);
	MessageBox.Show(nodeStack.Count.ToString());
}

private void Form1_NodeCollectionChanging(CollectionExEventArgs e)
{
	MessageBox.Show("NodeCollectionChanging event fired");
}

VB.NET

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
DirectCast(diagram1.EventSink, DiagramViewerEventSink).NodeCollectionChanged += New CollectionExEventHandler(Form1_NodeCollectionChanged)(DirectCast(diagram1.EventSink, DiagramViewerEventSink)).NodeCollectionChanging += New CollectionExEventHandler(Form1_NodeCollectionChanging)
Dim rect As New RectangleF(100, 100, 100, 100)
Dim richText As New RichTextNode("", rect)
richText.Text = "Rich text box"
Dim nodeStack As New NodeCollection()
nodeStack.Add(richText)
MessageBox.Show(nodeStack.Count.ToString())
End Sub

Private Sub Form1_NodeCollectionChanging(ByVal e As CollectionExEventArgs)
MessageBox.Show("NodeCollectionChanging event fired")
End Sub

Sample diagrams are as follows,

Node Mouse Events

This topic discusses the events that are raised when mouse entering or leaving the node. The below table discusses all the available node mouse events.

Node Mouse Events

DiagramViewerEventSink	Description
NodeClick	Triggered when mouse clicked on the node.
NodeDoubleClick	Triggered when mouse double clicked on the node.
NodeMouseEnter	Triggered when mouse enter into the node.
NodeMouseLeave	Triggered when mouse leaves the node.

EventArgs members can be accessed using the following members.

Properties

NodeMouse EventArgs Member	Description
Node	Gets the node clicked. If a single node is clicked that node will be returned. If a node is clicked from a group it will return that group as a node.
Actual Node	Actual Nodes gets the exact node. If we click a node from group it will retrieve the exact node clicked.

C#

private void Form1_Load(object sender, EventArgs e)
{
	this.diagram1.EventSink.NodeMouseEnter += EventSink_NodeMouseEnter;
	this.diagram1.EventSink.NodeMouseLeave += EventSink_NodeMouseLeave; 
	this.diagram1.EventSink.NodeClick += EventSink_NodeClick;
    this.diagram1.EventSink.NodeDoubleClick += EventSink_NodeDoubleClick;      
}

void EventSink_NodeMouseEnter(Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs evtArgs)
{    
	MessageBox.Show("Node: " + evtArgs.Node.Name.ToString() +" , "+ "Actual Node: " + evtArgs.ActualNode.Name.ToString());    
}

void EventSink_NodeMouseLeave(Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs evtArgs)
{    
	MessageBox.Show("Node: " + evtArgs.Node.Name.ToString() + " , " + "Actual Node: " + evtArgs.ActualNode.Name.ToString());    
}
void EventSink_NodeDoubleClick(Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs evtArgs)
{
    MessageBox.Show("Node: " + evtArgs.Node.Name.ToString()); 
}

void EventSink_NodeClick(Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs evtArgs)
{
    MessageBox.Show("Node: " + evtArgs.Node.Name.ToString()); 
}

VB.NET

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler Me.diagram1.EventSink.NodeMouseEnter, AddressOf EventSink_NodeMouseEnter
AddHandler Me.diagram1.EventSink.NodeMouseLeave, AddressOf EventSink_NodeMouseLeave
AddHandler Me.diagram1.EventSink.NodeClick, AddressOf EventSink_NodeClick
AddHandler Me.diagram1.EventSink.NodeDoubleClick, AddressOf EventSink_NodeDoubleClick
End Sub

Private Sub EventSink_NodeMouseEnter(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs)
MessageBox.Show("Node: " & evtArgs.Node.Name.ToString() & " , " & "Actual Node: " & evtArgs.ActualNode.Name.ToString())
End Sub

Private Sub EventSink_NodeMouseLeave(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs)
MessageBox.Show("Node: " & evtArgs.Node.Name.ToString() & " , " & "Actual Node: " & evtArgs.ActualNode.Name.ToString())
End Sub

Private Sub EventSink_NodeClick(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs)
MessageBox.Show("Node: " & evtArgs.Node.Name.ToString())
End Sub

Private Sub EventSink_NodeDoubleClick(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.NodeMouseEventArgs)
MessageBox.Show("Node: " & evtArgs.Node.Name.ToString())
End Sub

Tool Events

The below events gets fired while activating or deactivating the UI tools (Zoom, Pan, Select etc) in the diagram.

The below table shows all the Tool Events.

Tool Events

DiagramViewerEventSink	Description
ToolActivated	Triggered when UI tool is activated.
ToolDeactivated	Triggered when UI tool is deactivated.

Data can be retrieved or set using the following members.

Members

ToolActivated / Deactivated EventArgs Members	Description
Tool	Returns the tools object that generated the event. It has following properties,Name - Name of the Tool.

In the below code sample, when a tool is activated or deactivated the corresponding event will be raised, and the tool name along with the status will be displayed.

C#

private void Form1_Load(object sender, EventArgs e)
{
	((DiagramViewerEventSink)diagram1.EventSink).ToolActivated += new ToolEventHandler(DiagramForm_ToolActivated);
	((DiagramViewerEventSink)diagram1.EventSink).ToolDeactivated += new ToolEventHandler(Form1_ToolDeactivated);
	diagram1.Controller.ActivateTool("ZoomTool");
}

void Form1_ToolDeactivated(ToolEventArgs e)
{
	MessageBox.Show("Deactivated Tool Name: " + e.Tool.Name);
}

private void DiagramForm_ToolActivated(ToolEventArgs e)
{
	MessageBox.Show("Activated Tool Name: " + e.Tool.Name + "\n" + "Status: " + e.Tool.InAction);
}

VB.NET

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(diagram1.EventSink, DiagramViewerEventSink).ToolActivated, AddressOf DiagramForm_ToolActivated
AddHandler DirectCast(diagram1.EventSink, DiagramViewerEventSink).ToolDeactivated, AddressOf Form1_ToolDeactivated
diagram1.Controller.ActivateTool("ZoomTool")
End Sub

Private Sub Form1_ToolDeactivated(ByVal e As ToolEventArgs)
MessageBox.Show("Deactivated Tool Name: " & e.Tool.Name)
End Sub

Private Sub DiagramForm_ToolActivated(ByVal e As ToolEventArgs)
MessageBox.Show(("Activated Tool Name: " & e.Tool.Name & vbLf & "Status: ") + e.Tool.InAction)
End Sub

Sample diagrams are as follows,

Origin Events

The Origin changes when the diagram window is scrolled either horizontally or vertically.

Origin events are as follows,

Origin Events

DiagramViewerEventSink	Description
OriginChanged	Triggered when the origin is changed.

Data can be retrieved or set by using the following members.

Members

Origin EventArgs Member	Description
NewOrigin	Returns the new X and Y origin values after moving the origin.
Offset	Returns the difference between the old and new origin.
OriginalOrigin	Returns the X and Y values before moving the origin.

In the following code sample, when the OriginChanged event is handled, the various member values are listed in a text box as the control is scrolled accordingly.

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DiagramViewerEventSink)diagram1.EventSink).OriginChanged += new ViewOriginEventHandler(Form1_OriginChanged);
	NodeCollection nodeStack = new NodeCollection();
	
	// Circle
	Syncfusion.Windows.Forms.Diagram.Ellipse circle = new Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72);
	circle.Name = "Circle";
	circle.FillStyle.Type = FillStyleType.LinearGradient;
	circle.FillStyle.ForeColor = Color.AliceBlue;
	circle.ShadowStyle.Visible = true;
	nodeStack.Add(circle);
	
	// Polygon
	PointF[] pts ={ new Point(6, 36), new Point(48, 6), new Point(90, 36), new Point(48, 66) };
	Polygon polygon = new Polygon(pts);
	polygon.Name = "Polygon";
	polygon.FillStyle.ForeColor = Color.DarkSeaGreen;
	polygon.FillStyle.Color = Color.DarkSeaGreen;
	nodeStack.Add(polygon);
	
	int i = 0;
	this.model4.AppendChildren(nodeStack, out i);
	MessageBox.Show("Node count =" + "\n" + nodeStack.Count.ToString());
	textBox1.Text = model4.Nodes.Last.Name;
	this.diagram1.HScroll = true;
	this.diagram1.VScroll = true;
}

private void Form1_OriginChanged(ViewOriginEventArgs e)
{
	textBox1.Text = "X = " + e.OriginalOrigin.X + "," + "Y = " + e.OriginalOrigin.Y + "  " + "New X= " + e.NewOrigin.X + "," + "New 	Y= " + e.NewOrigin.Y;
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(diagram1.EventSink, DiagramViewerEventSink).OriginChanged, AddressOf Form1_OriginChanged
Dim nodeStack As New NodeCollection()

' Circle
Dim circle As New Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72)
circle.Name = "Circle"
circle.FillStyle.Type = FillStyleType.LinearGradient
circle.FillStyle.ForeColor = Color.AliceBlue
circle.ShadowStyle.Visible = True
nodeStack.Add(circle)

' Polygon
Dim pts As PointF() = {New Point(6, 36), New Point(48, 6), New Point(90, 36), New Point(48, 66)}
Dim polygon As New Polygon(pts)
polygon.Name = "Polygon"
polygon.FillStyle.ForeColor = Color.DarkSeaGreen
polygon.FillStyle.Color = Color.DarkSeaGreen
nodeStack.Add(polygon)

Dim i As Integer = 0
Me.model4.AppendChildren(nodeStack, i)
MessageBox.Show(("Node count =" & vbLf) + nodeStack.Count.ToString())
textBox1.Text = model4.Nodes.Last.Name
Me.diagram1.HScroll = True
Me.diagram1.VScroll = True
End Sub

Private Sub Form1_OriginChanged(ByVal e As ViewOriginEventArgs)
textBox1.Text = ((("X = " & e.OriginalOrigin.X & "," & "Y = ") + e.OriginalOrigin.Y & "  " & "New X= ") + e.NewOrigin.X & "," & "New " & vbTab & "Y= ") + e.NewOrigin.Y
End Sub

Sample diagrams are as follows.

Magnification Event

When the control is zoomed in or out, the magnification events will be fired displaying the old and new magnification factors.

Magnification Events are as follows,

Magnification Events

DiagramViewerEventSink	Description
MagnificationChanged	Fired when magnification value is changed.

Data can be retrieved or set using the following members.

Member properties

Magnification EventArgs Member	Description
NewMagnification	Returns the new magnification value.
OriginalMagnification	Returns the old magnification value before the event occurred.

C#

private void Form1_Load(object sender, EventArgs e)
{
((DiagramViewerEventSink)diagram1.EventSink).MagnificationChanged += new ViewMagnificationEventHandler(Form1_MagnificationChanged);
}

[EventHandlerPriorityAttribute(true)]
private void Form1_MagnificationChanged(ViewMagnificationEventArgs evtArgs)
{
MessageBox.Show("Old Factor: " + evtArgs.OriginalMagnification.ToString() + "New Factor: " + evtArgs.NewMagnification.ToString());
}

VB.NET

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(diagram1.EventSink, DiagramViewerEventSink).MagnificationChanged, AddressOf Form1_MagnificationChanged
End Sub

Private Sub Form1_MagnificationChanged(ByVal evtArgs As ViewMagnificationEventArgs)
MessageBox.Show(("Old Factor: " & evtArgs.OriginalMagnification.ToString() & "New Factor: ") + evtArgs.NewMagnification.ToString())
End Sub

Sample diagrams are as follows,

Editor Events

Diagram control provides support to notify users when the text in the Text Editor and Label Editor are changed. The following table lists the Editor events associated with Diagram control.

Editor Events

Event Name	Description
TextChanged	This event is raised when the text in the text editor is changed.
LabelTextChanged	This event is raised when the text in the label editor is changed.
KeyDown	This event is raised whenever a key is pressed in the text editor.
TextEditingCompleted	This event is raised when the text editing in the text editor is completed.

The following code example illustrates how the TextChanged and LabelTextChanged events are raised when the text in the text editor and label editor are changed respectively.

C#

private void Form1_Load(object sender, EventArgs e)
{
	diagram1.Controller.TextEditor.TextChanged += new EventHandler(TextEditor_TextChanged);
	diagram1.Controller.InPlaceEditor.LabelTextChanged += new EventHandler(InPlaceEditor_LabelTextChanged); 
	diagram1.Controller.TextEditor.KeyDown += TextEditor_KeyDown;
	diagram1.Controller.TextEditor.TextEditingCompleted += TextEditor_TextEditingCompleted;
}

void TextEditor_TextChanged(object sender, EventArgs e)
{
	MessageBox.Show("Text :" + this.diagram1.Controller.TextEditor.Text);
}

void InPlaceEditor_LabelTextChanged(object sender, EventArgs e)
{
	MessageBox.Show("Text :" + this.diagram1.Controller.InPlaceEditor.Text);
}  

void TextEditor_KeyDown(object sender, KeyEventArgs e)
{
	MessageBox.Show("Key Down:" + e.KeyData);
}

void TextEditor_TextEditingCompleted(object sender, Syncfusion.Windows.Forms.Diagram.LabelEditingCompletedEventArgs evtArgs)
{
	MessageBox.Show("Text Edit Completed:" + evtArgs.Value.ToString());
}

VB.NET

Private Sub Form1_Load(sender As Object, e As EventArgs)    
diagram1.Controller.TextEditor.TextChanged += New EventHandler(AddressOf TextEditor_TextChanged)
diagram1.Controller.InPlaceEditor.LabelTextChanged += New EventHandler(AddressOf InPlaceEditor_LabelTextChanged)        
diagram1.Controller.TextEditor.KeyDown += New EventHandler(AddressOf TextEditor_KeyDown)
diagram1.Controller.TextEditor.TextEditingCompleted += New EventHandler(AddressOf TextEditor_TextEditingCompleted)    
End Sub

Private Sub TextEditor_TextChanged(sender As Object, e As EventArgs)
MessageBox.Show("Text :" & Convert.ToString(Me.diagram1.Controller.TextEditor.Text))
End Sub

Private Sub InPlaceEditor_LabelTextChanged(sender As Object, e As EventArgs)
MessageBox.Show("Text :" & Convert.ToString(Me.diagram1.Controller.InPlaceEditor.Text))
End Sub

Private Sub TextEditor_KeyDown(ByVal sender As Object, ByVal e As KeyEventArgs)
MessageBox.Show("Key Down:" & e.KeyData)
End Sub

Private Sub TextEditor_TextEditingCompleted(ByVal sender As Object, ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.LabelEditingCompletedEventArgs)
MessageBox.Show("Text Edit Completed:" & evtArgs.Value.ToString())
End Sub

Model Events

DocumentEventSink class contains the events specific to the document. The various events that can be invoked using this class are discussed in the following topics.

Vertex Events

Vertex Events are as follows,

Vertex Events

DocumentEventSink	Description
VertexChanged	Gets fired after the vertex of the node has been changed.
VertexChanging	Gets fired when the vertex of the node is changed.

Data can be retrieved or set using the following members.

Description

Vertex EventArgs Member	Description
Cancel	Cancels the Vertex Changed event from being fired.
ChangeType	It returns the following possible value:Set - whether the vertex is set for the node.
NodeAffected	Returns the node's name by which the node was affected.
VertexIndex	Returns the index of the current vertex.
Vertex EventArgs Member	Description
VertexLocation	Returns the position of the vertex.

Programmatically the events are written as follows,

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).VertexChanged += new VertexChangedEventHandler(Form1_VertexChanged);
	((DocumentEventSink)model1.EventSink).VertexChanging += new VertexChangingEventHandler(Form1_VertexChanging);
	LineConnector line = new LineConnector(circle.PinPoint, polygon.PinPoint);
	polygon.CentralPort.TryConnect(line.HeadEndPoint);
	circle.CentralPort.TryConnect(line.TailEndPoint);
	model1.AppendChild(line);
}

private void Form1_VertexChanging(VertexChangingEventArgs vertexChange)
{
	MessageBox.Show("VertexChanging fired");
	model1.LineStyle.LineWidth = 2;
}

private void Form1_VertexChanged(VertexChangedEventArgs vertexChange)
{
	MessageBox.Show("Target Node - " + vertexChange.NodeAffected.FullName + "\n" + vertexChange.VertexLocation.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).VertexChanged, AddressOf Form1_VertexChanged
AddHandler DirectCast(model1.EventSink, DocumentEventSink).VertexChanging, AddressOf Form1_VertexChanging
Dim line As New LineConnector(circle.PinPoint, polygon.PinPoint)
polygon.CentralPort.TryConnect(line.HeadEndPoint)
circle.CentralPort.TryConnect(line.TailEndPoint)
model1.AppendChild(line)
End Sub

Private Sub Form1_VertexChanging(ByVal vertexChange As VertexChangingEventArgs)
MessageBox.Show("VertexChanging fired")
model1.LineStyle.LineWidth = 2
End Sub

Private Sub Form1_VertexChanged(ByVal vertexChange As VertexChangedEventArgs)
MessageBox.Show(("Target Node - " & vertexChange.NodeAffected.FullName & vbLf) + vertexChange.VertexLocation.ToString())
End Sub

Sample diagrams are as follows,

PinPoint Events

When changing the node’s location, the pinpoint of the node will be reset. The below table contains pinpoint events and descriptions.

Pinpoint Events

DocumentEventSink	Description
PinOffsetChanged	Triggered after the offset of the pinpoint is reset.
PinOffsetChanging	Triggered when the offset of the pinpoint is changed.
PinPointChanged	Triggered after the pinpoint is repositioned.
PinPointChanging	Triggered when the pinpoint is moved.

Data can be retrieved or set using the following members.

Members

PinPoint / PinPointOffset EventArgs Member	Description
Cancel	Cancels the PinPoint Changing events.
NodeAffected	Returns the node's name by which the node was affected.
Offset	Returns the X and Y values.

Programmatically the events are written as follows,

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model4.EventSink).PinOffsetChanged += new PinOffsetChangedEventHandler(Form1_PinOffsetChanged);
	((DocumentEventSink)model4.EventSink).PinOffsetChanging += new PinOffsetChangingEventHandler(Form1_PinOffsetChanging);
	((DocumentEventSink)model4.EventSink).PinPointChanged += new PinPointChangedEventHandler(Form1_PinPointChanged);
	((DocumentEventSink)model4.EventSink).PinPointChanging += new PinPointChangingEventHandler(Form1_PinPointChanging);
	
	// Circle
	Syncfusion.Windows.Forms.Diagram.Ellipse circle = new Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72);
	circle.Name = "Circle";
	circle.FillStyle.Type = FillStyleType.LinearGradient;
	circle.FillStyle.ForeColor = Color.AliceBlue;
	circle.ShadowStyle.Visible = true;
	model4.AppendChild(circle);
}

void Form1_PinPointChanging(PinPointChangingEventArgs evtArgs)
{
	MessageBox.Show("PinpointChanging event is fired" + "\n" + "Node name: " + evtArgs.NodeAffected.Name.ToString());
}

void Form1_PinPointChanged(PinPointChangedEventArgs evtArgs)
{
	MessageBox.Show("PinPointChanged event is fired" + "\n" + "Offset values: " + evtArgs.Offset.ToString());
}

void Form1_PinOffsetChanging(PinOffsetChangingEventArgs evtArgs)
{
	MessageBox.Show("PinOffsetChanging event is fired" + "\n" + "Node name: " + evtArgs.NodeAffected.Name);
}

void Form1_PinOffsetChanged(PinOffsetChangedEventArgs evtArgs)
{
	MessageBox.Show("PinOffsetChanged event is fired" + "\n" + "Offset values: " + evtArgs.Offset.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model4.EventSink, DocumentEventSink).PinOffsetChanged, AddressOf Form1_PinOffsetChanged
AddHandler DirectCast(model4.EventSink, DocumentEventSink).PinOffsetChanging, AddressOf Form1_PinOffsetChanging
AddHandler DirectCast(model4.EventSink, DocumentEventSink).PinPointChanged, AddressOf Form1_PinPointChanged
AddHandler DirectCast(model4.EventSink, DocumentEventSink).PinPointChanging, AddressOf Form1_PinPointChanging

' Circle
Dim circle As New Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72)
circle.Name = "Circle"
circle.FillStyle.Type = FillStyleType.LinearGradient
circle.FillStyle.ForeColor = Color.AliceBlue
circle.ShadowStyle.Visible = True
model4.AppendChild(circle)
End Sub

Private Sub Form1_PinPointChanging(ByVal evtArgs As PinPointChangingEventArgs)
MessageBox.Show(("PinpointChanging event is fired" & vbLf & "Node name: ") + evtArgs.NodeAffected.Name.ToString())
End Sub

Private Sub Form1_PinPointChanged(ByVal evtArgs As PinPointChangedEventArgs)
MessageBox.Show(("PinPointChanged event is fired" & vbLf & "Offset values: ") + evtArgs.Offset.ToString())
End Sub

Private Sub Form1_PinOffsetChanging(ByVal evtArgs As PinOffsetChangingEventArgs)
MessageBox.Show(("PinOffsetChanging event is fired" & vbLf & "Node name: ") + evtArgs.NodeAffected.Name)
End Sub

Private Sub Form1_PinOffsetChanged(ByVal evtArgs As PinOffsetChangedEventArgs)
MessageBox.Show(("PinOffsetChanged event is fired" & vbLf & "Offset values: ") + evtArgs.Offset.ToString())
End Sub

Sample diagrams are as follows,

Rotation Events

When the control is rotated horizontally or vertically, the rotation events will be fired displaying the rotation offsets.

The below table discusses the available rotation events with descriptions.

Rotation Events

DocumentEventSink	Description
FlipChanged	Triggered after the node is rotated using Flip property.
FlipChanging	Triggered when the node is rotated using Flip property.
RotationChanged	Triggered after the node is rotated.
RotationChanging	Triggered on rotating the node in any direction.

Data can be retrieved or set using the following members.

Members

Rotation EventArgs Member	Description
NodeAffected	Returns the node's name by which the node was affected.
RotationOffset	Returns the angle by which the node was rotated.

Flip EventArgs Member

Flip EventArgs Member	Description
Cancel	Cancels the FlipChanging event.
FlipAxis	Returns the axis around which the node was rotated.
FlipValue	Returns the boolean value of the Flip property.
NodeAffected	Returns the node's name by which the node was affected.

Programmatically, the events are written as follows:

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).FlipChanged += new FlipChangedEventHandler(Form1_FlipChanged);
	((DocumentEventSink)model1.EventSink).FlipChanging += new FlipChangingEventHandler(Form1_FlipChanging);
	((DocumentEventSink)model1.EventSink).RotationChanged += new RotationChangedEventHandler(Form1_RotationChanged);
	((DocumentEventSink)model1.EventSink).RotationChanging += new RotationChangingEventHandler(Form1_RotationChanging);
	
	// Circle
	Syncfusion.Windows.Forms.Diagram.Ellipse circle = new Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72);
	circle.Name = "Circle";
	circle.FillStyle.Type = FillStyleType.LinearGradient;
	circle.FillStyle.ForeColor = Color.AliceBlue;
	circle.ShadowStyle.Visible = true;
	model4.AppendChild(circle);
}

void Form1_RotationChanged(RotationChangedEventArgs evtArgs)
{
	MessageBox.Show("RotationChanged event is fired" + "\n" + evtArgs.RotationOffset.ToString());
}

void Form1_FlipChanging(FlipChangingEventArgs evtArgs)
{
	MessageBox.Show("FlipChanging event is fired");
	textBox1.Text = evtArgs.NodeAffected.BoundingRectangle.ToString();
}

void Form1_FlipChanged(FlipChangedEventArgs evtArgs)
{
	MessageBox.Show("FlipChanged event is fired" + "\n" + "Flip Axis:" + evtArgs.FlipAxis.ToString() + "\n" + "Node: " + evtArgs.NodeAffected.Name.ToString());
	evtArgs.NodeAffected.EditStyle.Enabled = false;
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).FlipChanged, AddressOf Form1_FlipChanged
AddHandler DirectCast(model1.EventSink, DocumentEventSink).FlipChanging, AddressOf Form1_FlipChanging
AddHandler DirectCast(model1.EventSink, DocumentEventSink).RotationChanged, AddressOf Form1_RotationChanged
AddHandler DirectCast(model1.EventSink, DocumentEventSink).RotationChanging, AddressOf Form1_RotationChanging

' Circle
Dim circle As New Syncfusion.Windows.Forms.Diagram.Ellipse(0, 0, 96, 72)
circle.Name = "Circle"
circle.FillStyle.Type = FillStyleType.LinearGradient
circle.FillStyle.ForeColor = Color.AliceBlue
circle.ShadowStyle.Visible = True
model4.AppendChild(circle)
End Sub

Private Sub Form1_RotationChanged(ByVal evtArgs As RotationChangedEventArgs)
MessageBox.Show(("RotationChanged event is fired" & vbLf) + evtArgs.RotationOffset.ToString())
End Sub

Private Sub Form1_FlipChanging(ByVal evtArgs As FlipChangingEventArgs)
MessageBox.Show("FlipChanging event is fired")
textBox1.Text = evtArgs.NodeAffected.BoundingRectangle.ToString()
End Sub

Private Sub Form1_FlipChanged(ByVal evtArgs As FlipChangedEventArgs)
MessageBox.Show((("FlipChanged event is fired" & vbLf & "Flip Axis:") + evtArgs.FlipAxis.ToString() & vbLf & "Node: ") + evtArgs.NodeAffected.Name.ToString())
evtArgs.NodeAffected.EditStyle.Enabled = False
End Sub

Sample diagrams are as follows:

Z-Order Events

When the node order is changed from front-to-back or back-to-front, the Z-order value gets changed and triggers the Z-order events listed in the below table.

Z-order events

DocumentEventSink	Description
ZOrderChanged	Gets fired after the Z-order value is changed.
ZOrderChanging	Gets fired when the Z-order of the node is changed.

Data can be retrieved / set by using the following members.

Members

Z-order EventArgs Members	Description
Cancel	Cancels the Z-order changing event.
ChangeType	It returns the following possible values,* Front-whether the controller bring the node to the front* Back-whether the controller send the node to the back
NodeAffected	Returns the node's name by which the node was affected.
Z-order	Returns the current Z-order value.

Programmatically, the events are written as follows:

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).ZOrderChanged += new ZOrderChangedEventHandler(Form1_ZOrderChanged);
	((DocumentEventSink)model1.EventSink).ZOrderChanging += new ZOrderChangingEventHandler(Form1_ZOrderChanging);
	diagram1.Controller.BringToFront();
}

void Form1_ZOrderChanging(ZOrderChangingEventArgs evtArgs)
{
	MessageBox.Show("ZOrderChanging event is fired" + "\n" + "Node: " + evtArgs.NodeAffected.Name.ToString());
}

void Form1_ZOrderChanged(ZOrderChangedEventArgs evtArgs)
{
	MessageBox.Show("ZOrderChanged event is fired" + "\n" + "New ZOrder: " + evtArgs.ZOrder.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).ZOrderChanged, AddressOf Form1_ZOrderChanged
AddHandler DirectCast(model1.EventSink, DocumentEventSink).ZOrderChanging, AddressOf Form1_ZOrderChanging
diagram1.Controller.BringToFront()
End Sub

Private Sub Form1_ZOrderChanging(ByVal evtArgs As ZOrderChangingEventArgs)
MessageBox.Show(("ZOrderChanging event is fired" & vbLf & "Node: ") + evtArgs.NodeAffected.Name.ToString())
End Sub

Private Sub Form1_ZOrderChanged(ByVal evtArgs As ZOrderChangedEventArgs)
MessageBox.Show(("ZOrderChanged event is fired" & vbLf & "New ZOrder: ") + evtArgs.ZOrder.ToString())
End Sub

Sample diagram are as follows:

Connections And Ports Events

The below events gets fired while the connection is created between two nodes.

The below table explains the Connections and Ports events.

Connections and Ports Events

DocumentEventSink	Description
ConnectionsChanged	Triggered after the connection is changed.
PortsChanged	Triggered when ports are added or changed.

Data can be retrieved or set using the following members.

Members

Connection and Port EventArgs Member	Description
Cancel	Cancels the ConnectionChanging event.
ChangeType	It returns the following possible values:Insert-Whether the node is insertedRemove–Whether the node is removed
Element	Returns whether the head or tail end is moved.
Elements	Returns the elements collection on which the event occurs.
Index	Returns the zero-based index into the collection on which the event occurred.
Owner	Returns the owner object. This is a read-only boolean value.

Connection Events

Programmatically, the Connection Event is handled as follows.

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).ConnectionsChanged += new CollectionExEventHandler(Form1_ConnectionsChanged);
	LineConnector line = new LineConnector(circle.PinPoint, polygon.PinPoint);
	polygon.CentralPort.TryConnect(line.HeadEndPoint);
	circle.CentralPort.TryConnect(line.TailEndPoint);
	model1.AppendChild(line);
}

void Form1_ConnectionsChanged(CollectionExEventArgs evtArgs)
{
	MessageBox.Show(evtArgs.ChangeType.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).ConnectionsChanged, AddressOf Form1_ConnectionsChanged
Dim line As New LineConnector(circle.PinPoint, polygon.PinPoint)
polygon.CentralPort.TryConnect(line.HeadEndPoint)
circle.CentralPort.TryConnect(line.TailEndPoint)
model1.AppendChild(line)
End Sub

Private Sub Form1_ConnectionsChanged(ByVal evtArgs As CollectionExEventArgs)
MessageBox.Show(evtArgs.ChangeType.ToString())
End Sub

Sample diagram is as follows.

Ports Events

Programmatically, the events are handled as follows.

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).PortsChanged += new CollectionExEventHandler(Form1_PortsChanged);
	node.EnableCentralPort = false;
}

void Form1_PortsChanged(CollectionExEventArgs evtArgs)
{
	MessageBox.Show("Port is changed");
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).PortsChanged, AddressOf Form1_PortsChanged
node.EnableCentralPort = False
End Sub

Private Sub Form1_PortsChanged(ByVal evtArgs As CollectionExEventArgs)
MessageBox.Show("Port is changed")
End Sub

Sample diagram is as follows.

Property Events

Each node has different properties (Name,Color,Size etc). The below events are handled when changing these properties.

Property Events are as follows.

Property Events

DocumentEventSink	Description
PropertyChanged	Triggered after the property of any node is changed.
PropertyChanging	Triggered when the property value is changed.

Data can be retrieved or set using the following members.

Members

PropertyChanging EventArgs Member	Description
Cancel	Cancels the PropertyChanged event.
NewValue	Returns the new value assigned to the property.
PropertyContainer	Returns the container for the property.
PropertyName	Returns name of the property whose value is changed.

Members

PropertyChanged EventArgs Member	Description
NodeAffected	Returns the name of the node whose property is changed.
PropertyName	Returns the name of the property whose value is changed.

Programmatically the events are written as follows,

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).PropertyChanged += new Syncfusion.Windows.Forms.Diagram.PropertyChangedEventHandler
	(Form1_PropertyChanged);
	((DocumentEventSink)model1.EventSink).PropertyChanging += new PropertyChangingEventHandler(Form1_PropertyChanging);
}

private void Form1_PropertyChanged(Syncfusion.Windows.Forms.Diagram.PropertyChangedEventArgs evtArgs)
{
	MessageBox.Show("PropertyChanged event is fired" + "\n" + "Property Name: " + evtArgs.PropertyName);
}

private void Form1_PropertyChanging(Syncfusion.Windows.Forms.Diagram.PropertyChangingEventArgs eprop)
{
	MessageBox.Show("PropertyChanging event is fired" + "\n" + "Property Name: " + eprop.PropertyName + "\n" + "new 				Value: " + eprop.NewValue);
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).PropertyChanged, AddressOf Form1_PropertyChanged
AddHandler DirectCast(model1.EventSink, DocumentEventSink).PropertyChanging, AddressOf Form1_PropertyChanging
End Sub

Private Sub Form1_PropertyChanged(ByVal evtArgs As Syncfusion.Windows.Forms.Diagram.PropertyChangedEventArgs)
MessageBox.Show(("PropertyChanged event is fired" & vbLf & "Property Name: ") + evtArgs.PropertyName)
End Sub

Private Sub Form1_PropertyChanging(ByVal eprop As Syncfusion.Windows.Forms.Diagram.PropertyChangingEventArgs)
MessageBox.Show((("PropertyChanging event is fired" & vbLf & "Property Name: ") + eprop.PropertyName & vbLf & "new " & vbTab & vbTab & vbTab & vbTab & "Value: ") + eprop.NewValue)
End Sub

Sample diagrams are as follows.

Labels And Layers Events

The below mentioned events are fired, when adding or removing the labels and layers to or from the diagram.

The following table shows the label events:

Labels And Layers Events

DocumentEventSink	Description
LabelsChanged	Triggered when labels are added.
LayersChanged	Triggered when layers are added to the model.

Data can be retrieved or set using the following members.

Label / Layers EventArgs Member	Description
Cancel	Cancels the LabelChanging event.
ChangeType	It returns the following possible values:Insert-Whether the label is insertedRemove–Whether the label is removed
Element	Returns whether the head or tail end is moved.
Elements	Returns the elements collection on which the event occurs.
Index	Returns the zero-based index into the collection on which the event occurred.
Owner	Returns the owner object.

Label Events

Whenever labels are added to the label collection, this event will be triggered.

Programmatically, the events are written as follows:

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).LabelsChanged += new CollectionExEventHandler(Form1_LabelsChanged);
}

void Form1_LabelsChanged(CollectionExEventArgs evtArgs)
{
	MessageBox.Show("LabelsChanged event is fired" + evtArgs.ChangeType.ToString() + evtArgs.Owner.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).LabelsChanged, AddressOf Form1_LabelsChanged
End Sub

Private Sub Form1_LabelsChanged(ByVal evtArgs As CollectionExEventArgs)
MessageBox.Show(("LabelsChanged event is fired" & evtArgs.ChangeType.ToString()) + evtArgs.Owner.ToString())
End Sub

Layers Events

Programmatically, the events are written as follows:

C#

public void Form1_Load(object sender, EventArgs e)
{
	((DocumentEventSink)model1.EventSink).LayersChanged += new CollectionExEventHandler(Form1_LayersChanged);
	Layer layer0 = new Layer();
	this.diagram1.Model.Layers.Add(layer0);
	layer0.Enabled = true;
	layer0.Visible = true;
}

void Form1_LayersChanged(CollectionExEventArgs evtArgs)
{
	MessageBox.Show("LayersChanged event is fired." + "\n" + "Owner: " + evtArgs.Owner.ToString());
}

VB.NET

Public Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler DirectCast(model1.EventSink, DocumentEventSink).LayersChanged, AddressOf Form1_LayersChanged
Dim layer0 As New Layer()
Me.diagram1.Model.Layers.Add(layer0)
layer0.Enabled = True
layer0.Visible = True
End Sub

Private Sub Form1_LayersChanged(ByVal evtArgs As CollectionExEventArgs)
MessageBox.Show(("LayersChanged event is fired." & vbLf & "Owner: ") + evtArgs.Owner.ToString())
End Sub

Sample diagram is as follows,