Redaction in WPF Pdf Viewer

15 Nov 202211 minutes to read

Redaction support allows you to remove sensitive/confidential information in text, images, and graphics from a PDF document.

NOTE

From version 19.4.0.48, we have updated our default text extraction engine to PDFium for extracting text information from PDF documents. Based on the text information, we redact text in the PDF documents. Please refer to the link for more details.

Enable redaction mode

The following code shows how to switch to redaction mode in code behind.

C#
VB.NET
private void button1_Click(object sender, RoutedEventArgs e)
{
      //Enables redaction mode
      pdfviewer.PageRedactor.EnableRedactionMode = true;
}
Private Sub button1_Click(sender As Object, e As RoutedEventArgs)
     'Enables redaction mode
     pdfviewer.PageRedactor.EnableRedactionMode = true
End Sub

Mark region to redact

Use the following steps to perform redaction in the PDF document page:

Click the redaction tool button in the left pane, this displays the redaction toolbar as a secondary toolbar in the PdfViewerControl.
Select Mark for Redaction from redaction toolbar to select the region or text to be redacted
Use the mouse pointer to select the region or the text to be redacted. This operation will create a mark in the region selected.
Choose Apply in the redaction toolbar to redact the marked region.

NOTE

Undo and redo can only be performed before applying the redaction, these operations cannot be performed after applying redaction.

Mark regions for redaction without UI interaction

You can also mark regions for redaction without UI interaction from the code behind using the MarkRegions method. Refer to the following code to mark the regions by passing the page index and the list of rectangle regions to be marked in the particular page for redaction.

C#
private void Button_Click(object sender, RoutedEventArgs e)
{            
	List<RectangleF> rectangles = new List<RectangleF>();
	rectangles = new List<RectangleF>() { new RectangleF(100, 100, 100, 100) };

	// Appends regions to the existing marked regions, marking regions if it does not already exist.
	pdfViewerControl.PageRedactor.MarkRegions(0, rectangles, false);
	// Enable the redaction mode.
	pdfViewerControl.PageRedactor.EnableRedactionMode = true;
}

NOTE

You can overwrite the existing marked regions with the new regions, By passing the value true for the clearExisting parameter of MarkRegions method.

Customizing redaction appearance

Choosing Properties from the redaction toolbar will show the default Redaction Tool Properties window, which contain two tabs:

• Appearance
• General

Appearance tab

The redacted area fill color, overlay text, and redaction mark area appearances can be customized using the options in the Appearance tab.

Redaction appearance

The following image illustrates how to change the fill color of the redacted area.

Redact fill color

The following code shows how to change the redacted area fill color from code behind.

C#
VB.NET
private void button1_Click(object sender, RoutedEventArgs e)
{
      //Sets the redacted area fill color
     pdfviewer.RedactionSettings.FillColor = Colors.AliceBlue;
}
Private Sub button1_Click(sender As Object, e As RoutedEventArgs)
         'Sets the redacted area fill color
         pdfviewer.RedactionSettings.FillColor = Colors.AliceBlue
End Sub

The following image illustrates how to change the overlay text appearance of the redacted area. You can disable the overlay text appearance by unchecking the Use Overlay Text checkbox.

Overlay text appearance

The following code shows how to customize the overlay text appearance from code behind.

C#
VB.NET
private void button1_Click(object sender, RoutedEventArgs e)
{
    //Set the overlay text
    pdfviewer.RedactionSettings.OverlayText = "overlay text";
    //Sets the overlay text font color 
    pdfviewer.RedactionSettings.FontColor = Colors.Blue;
    //Sets the overlay text font family 
    pdfviewer.RedactionSettings.FontFamily = new System.Windows.Media.FontFamily("Times new Roman");
    //Sets the overlay text font size
    pdfviewer.RedactionSettings.FontSize = 17;
    //Enable the overlay text appearance 
    pdfviewer.RedactionSettings.UseOverlayText = true;
}
Private Sub button1_Click(sender As Object, e As RoutedEventArgs)
    'Set the overlay text
    pdfviewer.RedactionSettings.OverlayText = "overlay text"
    'Sets the overlay text font color 
    pdfviewer.RedactionSettings.FontColor = Colors.Blue
    'Sets the overlay text font family 
    pdfviewer.RedactionSettings.FontFamily = new System.Windows.Media.FontFamily("Times new Roman")
    'Sets the overlay text font size
    pdfviewer.RedactionSettings.FontSize = 17
    'Enable the overlay text appearance 
    pdfviewer.RedactionSettings.UseOverlayText = true
End Sub

Marked redaction appearance

The marked redaction appearance represents the appearance of the region or text marked for redaction before the redaction is being applied. The fill color, border color, and fill color opacity of the redaction marked area can also be customized.

The following image illustrates how to customize the appearance of the redaction marked area.

Redaction Mark Appearance

The following code shows how to customize the appearance of mark for redaction area from code behind.

C#
VB.NET
private void button1_Click(object sender, RoutedEventArgs e)
{
    //Sets the redact mark area fill color
    pdfviewer.RedactionSettings.MarkAppearance.FillColor = Colors.Green;
    //Sets the redact mark area fill color opacity
    pdfviewer.RedactionSettings.MarkAppearance.FillOpacity = 0.5f;
    //Sets the redact mark area outline color 
    pdfviewer.RedactionSettings.MarkAppearance.OutlineColor = Colors.Yellow;
}
Private Sub button1_Click(sender As Object, e As RoutedEventArgs)
    'Sets the redact mark area fill color
    pdfviewer.RedactionSettings.MarkAppearance.FillColor = Colors.Green
    'Sets the redact mark area fill color opacity
    pdfviewer.RedactionSettings.MarkAppearance.FillOpacity = 0.5f
    'Sets the redact mark area outline color 
    pdfviewer.RedactionSettings.MarkAppearance.OutlineColor = Colors.Yellow
End Sub

The following image illustrates the appearance changes in redaction marked region.

Redaction Marked

General tab

You can add or edit the Author and Subject of the redaction using General tab of the Redaction Tool Properties window.
The following image illustrates the customization of Author and Subject of the redaction.

Redaction General Settings

Appearance of the included redaction

Selecting the properties option from the context menu that is displayed when right-clicking the selected redaction will show the Redaction Tool Properties window of selected redaction.
The following image illustrates how to customize the appearance of the included redaction.

Redaction Properties

Open pop-ups

Notes can be added to the redaction marked region by choosing Open Pop-up note option from the context menu. The following image illustrates the notes added to the redaction marked region.

Redaction PopUp

Delete redaction marked region

Select the delete option from the context menu that is displayed when right-clicking the selected redaction marked region will delete the respective redaction from the PDF document.
The following image illustrates how to delete the included redaction from the PDF document.

Redaction Delete

Events

Redaction applied notification

The RedactionApplied event notifies you when the marked regions of the page(s) are redacted. It provides the details of the redacted region through the RedactionEventArgs. The following code shows how to wire the event in PdfViewerControl.

C#
using Syncfusion.Windows.PdfViewer;
using System.Collections.Generic;
using System.Windows;

namespace RedactionAppliedEventDemo
{    
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            pdfViewerControl.PageRedactor.RedactionApplied += PageRedactor_RedactionApplied;
            pdfViewerControl.Load(@"../../Data/PDF_Succinctly.pdf");
        }
        private void PageRedactor_RedactionApplied(object sender, Syncfusion.Windows.PdfViewer.RedactionEventArgs args)
        {
            //Collection of redacted regions for pdf pages
             List<RedactionMark> RedactedMarks = args.Marks;
            foreach (RedactionMark redactionMark in RedactedMarks)
            {
                //Bounds of the redacted region
                System.Drawing.RectangleF RedactedRegion = redactionMark.Bounds;
                //Brush color used to fill the redacted region
                System.Windows.Media.Color Fillcolor = redactionMark.Fill;
                //Page index of the redaction mark
                int pageIndex = redactionMark.PageIndex;
            }
        }
    }
}

Keyboard shortcuts

The following keyboard shortcuts are available to customize the marked redaction in the PDF document:
• Delete key: Deletes the selected mark redaction from the PDF document.
• Ctrl + Z: Performs undo functionality for recently performed operations.
• Ctrl + Y: Performs redo functionality for recently performed operations.

NOTE

All these operations can only be performed before applying the redaction.

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.