Handwritten Signature in WPF Pdf Viewer

15 Nov 202215 minutes to read

PDF viewer WPF allows the user to include handwritten signature in the PDF document and provides options to edit or remove the included handwritten signature in the PDF document.

The following code shows how to switch to handwritten signature mode in code behind.

C#
VBNET
private void Window_Loaded(object sender, RoutedEventArgs e)
{
    PdfLoadedDocument pdf = new PdfLoadedDocument("Input.pdf");
    pdfviewer.Load(pdf);
    pdfviewer.AnnotationMode = PdfDocumentView.PdfViewerAnnotationMode.HandwrittenSignature; 
}
Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Dim pdf As New PdfLoadedDocument(“Input.pdf”)
    pdfViewer.Load(pdf)
    pdfviewer.AnnotationMode = PdfDocumentView.PdfViewerAnnotationMode.HandwrittenSignature
End Sub

Moving to HandwrittenSignature mode will open the signature pad, requesting the user to draw the signature. Clicking on apply will add the signature in the PDF Document, this can then be resized and moved to appropriate location.

WPF PDF Viewer Handwritten Signature

How to set the opacity of the handwritten signature?

The opacity of the handwritten signature can be customized at the time of inclusion itself. The following code shows how to set opacity value of the handwritten signature to be included.

C#
VBNET
private void Window_Loaded(object sender, RoutedEventArgs e)
{
    PdfLoadedDocument pdf = new PdfLoadedDocument("Input.pdf");
    pdfviewer.Load(pdf);
    pdfviewer.HandwrittenSignatureSettings.Opacity = 0.5F;
}
Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Dim pdf As New PdfLoadedDocument(“Input.pdf”)
    pdfViewer.Load(pdf)
    pdfviewer.HandwrittenSignatureSettings.Opacity = 0.5F
End Sub

How to set the color of the handwritten signature?

The color of the handwritten signature can be customized at the time of inclusion itself.

C#
VBNET
private void Window_Loaded(object sender, RoutedEventArgs e)
{
    PdfLoadedDocument pdf = new PdfLoadedDocument("Input.pdf");
    pdfviewer.Load(pdf);
    pdfviewer.HandwrittenSignatureSettings.Color = Colors.Green; 
}
Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Dim pdf As New PdfLoadedDocument(“Input.pdf”)
    pdfViewer.Load(pdf)
    pdfviewer.HandwrittenSignatureSettings.Color = Colors.Green
End Sub

How to flatten handwritten signature on save?

The included handwritten signature can be flattened in the PDF document when saving it, setting FlattenSignatureOnSave Boolean to true in HandwrittenSignatureSettings will do this.

C#
VBNET
private void Window_Loaded(object sender, RoutedEventArgs e)
{
    PdfLoadedDocument pdf = new PdfLoadedDocument("Input.pdf");
    pdfviewer.Load(pdf);
    pdfviewer.HandwrittenSignatureSettings.FlattenSignatureOnSave = true; 
}
Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
    Dim pdf As New PdfLoadedDocument(“Input.pdf”)
    pdfViewer.Load(pdf)
    pdfviewer.HandwrittenSignatureSettings.FlattenSignatureOnSave = true
End Sub

NOTE

If the handwritten signature is not flattened, it will be saved as ink annotation in the PDF document.

Working with included handwritten signatures

The PDF viewer allows editing the color and opacity of the Handwritten signature included in the document in the UI.. To perform this, select the included handwritten signature and click right using mouse, over the selected handwritten signature, a pop-up context menu will appear with the following options,

Properties
Delete

Properties

Selecting properties from the context menu will display the Handwritten Signature Properties window, which would have Appearance tab.

Appearance tab

The color, opacity of the handwritten signature can be edited using Appearance tab of Handwritten Signature Properties window.

Editing color of the signature

The color of the selected handwritten signature will be displayed in the color row in the appearance tab. Selecting the Color would displays the color palette, choosing a color from the color palette and clicking OK will apply the color to the handwritten signature.

The following image illustrates how to change the color of the handwritten signature.

WPF PDF Viewer Edit Color of the Signature

Editing opacity of the signature

The slider displayed in the Appearance tab allows modifying opacity of the selected handwritten signature. You can also modify the opacity of the selected handwritten signature by giving numeric value in the opacity text box.

WPF PDF Viewer Edit Opacity of the Signature

Deleting a signature

Selecting delete option from the context menu which is displayed when clicking right on the selected signature would delete the respective signature from the PDF document.

WPF PDF Viewer Delete a Signature

Track the changes in a handwritten signature

You can track the changes occurred in a handwritten signature such as add, select, deselect, move, resize, and remove. The HandwrittenSignatureChanged event indicates that a signature is changed in the current document and the Action property of the HandwrittenSignatureChangedEventArgs provides you the type of changes made in the signature. The following code shows how to wire the event in PdfViewerControl.

C#
VBNET
PdfViewerControl pdfViewer = new PdfViewerControl();
pdfViewer.Load("Barcode.pdf");
pdfViewer.HandwrittenSignatureChanged += PdfViewer_HandwrittenSignatureChanged;

private void PdfViewer_HandwrittenSignatureChanged(object sender, HandwrittenSignatureChangedEventArgs e)
{
	//Insert your code that does something
}
Dim pdfViewer As PdfViewerControl = New PdfViewerControl()
pdfViewer.Load("Barcode.pdf")
AddHandler pdfViewer.HandwrittenSignatureChanged, AddressOf PdfViewer_HandwrittenSignatureChanged

Private Sub PdfViewer_HandwrittenSignatureChanged(ByVal sender As Object, ByVal e As HandwrittenSignatureChangedEventArgs)
'Insert your code that does something
End Sub

Get the added handwritten signature

You can get the added handwritten signature as System.Windows.Shapes.Path using the Signature property of the HandwrittenSignatureChangedEventArgs. Refer to the following code example for more details.

C#
VBNET
private void PdfViewer_HandwrittenSignatureChanged(object sender, HandwrittenSignatureChangedEventArgs e)
{           
	if (e.Action == AnnotationChangedAction.Add)
	{
		//Get the signature
		System.Windows.Shapes.Path signature = e.Signature as System.Windows.Shapes.Path;
	}
}
Private Sub PdfViewer_HandwrittenSignatureChanged(ByVal sender As Object, ByVal e As HandwrittenSignatureChangedEventArgs)
	If e.Action = AnnotationChangedAction.Add Then
		'Get the signature
		Dim signature As System.Windows.Shapes.Path = TryCast(e.Signature, System.Windows.Shapes.Path)
	End If

Track the changes in the location and size of a handwritten signature

You can track the changes in the location and size of a handwritten signature using the ` OldBounds and NewBounds properties of the HandwrittenSignatureChangedEventArgs`. Refer to the following code example for more details.

C#
VBNET
private void PdfViewer_HandwrittenSignatureChanged(object sender, HandwrittenSignatureChangedEventArgs e)
{    
	if(e.Action== AnnotationChangedAction.Move)
	{
		//Get the old location
		PointF oldLocation = e.OldBounds.Location;
		//Get the new location
		PointF newLocation = e.NewBounds.Location;
	}       
	else if(e.Action == AnnotationChangedAction.Resize)
	{
		//Get the old size
		SizeF oldSize = e.OldBounds.Size;
		//Get the new size
		SizeF newSize = e.NewBounds.Size;
	}
}
Private Sub PdfViewer_HandwrittenSignatureChanged(ByVal sender As Object, ByVal e As HandwrittenSignatureChangedEventArgs)
    If e.Action = AnnotationChangedAction.Move Then
	    'Get the old location
        Dim oldLocation As PointF = e.OldBounds.Location
	    'Get the new location
        Dim newLocation As PointF = e.NewBounds.Location
    ElseIf e.Action = AnnotationChangedAction.Resize Then
        'Get the old size
		Dim oldSize As SizeF = e.OldBounds.Size
        'Get the new size
		Dim newSize As SizeF = e.NewBounds.Size
    End If
End Sub

Track the details of the selected handwritten signature

You can track the details such as location, size, and page number of the selected handwritten signature using HandwrittenSignatureChangedEventArgs. Refer to the following code example for more details.

C#
VBNET
private void PdfViewer_HandwrittenSignatureChanged(object sender, HandwrittenSignatureChangedEventArgs e)
{
	if(e.Action== AnnotationChangedAction.Select)
	{
		//Get the page number
		int pageNumber = e.PageNumber;
		//Get the signature location
		PointF location = e.NewBounds.Location;
		//Get the signature size
		SizeF size = e.NewBounds.Size;
	}
}
Private Sub PdfViewer_HandwrittenSignatureChanged(ByVal sender As Object, ByVal e As HandwrittenSignatureChangedEventArgs)
    If e.Action = AnnotationChangedAction.[Select] Then
	    'Get the page number
        Dim pageNumber As Integer = e.PageNumber
	    'Get the signature location
        Dim location As PointF = e.NewBounds.Location
	    'Get the signature size
        Dim size As SizeF = e.NewBounds.Size
    End If
End Sub

Add handwritten signature from code

PDF Viewer allows you to add a signature anywhere in the pages of a PDF document from code behind.

Add a handwritten signature in a single page

You can add signature in a particular page as System.Windows.Shapes.Path by using the AddHandwrittenSignature with the page number and the bounds as parameters. The following code explains how to add a handwritten signature at the first page of the PDF document.

C#
VBNET
private void button_Click(object sender, RoutedEventArgs e)
{
	System.Windows.Shapes.Path signature = new System.Windows.Shapes.Path();
	//Note: Set your signature appearance as Data for the path here.
	//Add signature in the first page of the PDF document at the location: X= 450, Y=750 and with the size: Width=100, Height=100.
	pdfViewer.AddHandwrittenSignature(signature, 1, new RectangleF(450, 750, 100, 100));
}
Private Sub button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim signature As System.Windows.Shapes.Path = New System.Windows.Shapes.Path()
    'Note: Set your signature appearance as Data for the path here.
    'Add signature in the first page of the PDF document at the location: X= 450, Y=750 and with the size: Width=100, Height=100.
    pdfViewer.AddHandwrittenSignature(signature, 1, New RectangleF(450, 750, 100, 100))
End Sub

Add a handwritten signature in multiple pages

You can also add a signature in multiple pages of the PDF document at multiple places using the AddHandwrittenSignature method with the overload of dictionary with page numbers as keys and the list of bounds as values. The following code explains how to add a handwritten signature at the first and second page of the PDF document with different bounds.

C#
VBNET
private void button_Click(object sender, RoutedEventArgs e)
{
	System.Windows.Shapes.Path signature = new System.Windows.Shapes.Path();
	//Note: Set your signature appearance using `Data` property of the path here.
	Dictionary<int, List<RectangleF>> bounds = new Dictionary<int, List<RectangleF>>();
	//Add signature bounds for the first page as: X= 450, Y=750, Width=100, Height=100.
	bounds.Add(1, new List<RectangleF>() { new RectangleF(450, 750, 100, 100) });
	//Add signature bounds for the second page as: X= 350, Y=550, Width=200, Height=200
	bounds.Add(2, new List<RectangleF>() { new RectangleF(350, 550, 200, 200) });
	pdfViewer.AddHandwrittenSignature(signature, bounds);
}
Private Sub button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim signature As System.Windows.Shapes.Path = New System.Windows.Shapes.Path()
	'Note: Set your signature appearance using `Data` property of the path here.
    Dim bounds As Dictionary(Of Integer, List(Of RectangleF)) = New Dictionary(Of Integer, List(Of RectangleF))()
    'Add signature bounds for the first page as: X= 450, Y=750, Width=100, Height=100.
	bounds.Add(1, New List(Of RectangleF)() From {
        New RectangleF(450, 750, 100, 100)
    })	
	'Add signature bounds for the second page as: X= 350, Y=550, Width=200, Height=200.
    bounds.Add(2, New List(Of RectangleF)() From {
        New RectangleF(350, 550, 200, 200)
    })
    pdfViewer.AddHandwrittenSignature(signature, bounds)
End Sub

Keyboard shortcuts

The below keyboard shortcuts are available to customize the handwritten signature in the PDF document.

Delete key – Deletes the selected signature from the PDF document.
Ctrl + Z – Performs undo functionality for recently performed operations.
Ctrl + Y – Performs redo functionality for recently performed operations.

NOTE

You can refer to our WPF PDF Viewer feature tour page for its groundbreaking feature representations. You can also explore our WPF PDF Viewer example to know how to render and configure the pdfviewer.