Getting Started with Xamarin Pdf Viewer (SfPdfViewer)

21 Nov 202424 minutes to read

This section demonstrates how to create an application that displays a PDF file using Xamarin Pdf Viewer (SfPdfViewer) control.

Assembly deployment

After installing Essential Studio® for Xamarin, you can find all the required assemblies in the installation folders, {Syncfusion Essential Studio Installed location} \Essential Studio\{Version #}\Xamarin\lib.

E.g.: C:\Program Files (x86) \Syncfusion\Essential Studio\19.1.0.54\Xamarin\lib

NOTE

Assemblies can be found in unzipped package location(Documents/Syncfusion/{Version #}/Xamarin/lib) in Mac.

Adding SfPdfViewer reference

You can add SfPdfViewer reference using one of the following methods:

Method 1: Adding SfPdfViewer reference from nuget.org

Syncfusion Xamarin components are available in nuget.org. To add SfPdfViewer to your project, open the NuGet package manager in Visual Studio, search for Syncfusion.Xamarin.SfPdfViewer, and then install it.

Adding SfPdfViewer reference from NuGet

NOTE

Install the same version of SfPdfViewer NuGet in all the projects.

Method 2: Adding SfPdfViewer reference from toolbox

Syncfusion also provides Xamarin Toolbox. Using this toolbox, you can drag the SfPdfViewer control to the XAML page. It will automatically install the required NuGet packages and add the namespace to the page. To install Syncfusion Xamarin Toolbox, refer to Toolbox.

Method 3: Adding SfPdfViewer assemblies manually from the installed location

If you prefer to manually reference the assemblies instead referencing from NuGet, add the following assemblies in respective projects.

Location: {Installed location}/{version}/Xamarin/lib

PCL	Syncfusion.Compression.Portable.dll Syncfusion.Pdf.Portable.dll Syncfusion.SfPdfViewer.XForms.dll Syncfusion.SfBusyIndicator.XForms.dll Syncfusion.SfRangeSlider.XForms.dll Syncfusion.Core.XForms.dll Syncfusion.Licensing.dll Syncfusion.SfProgressBar.XForms.dll Syncfusion.SfTabView.XForms.dll
Android	Syncfusion.Compression.Portable.dll Syncfusion.Pdf.Portable.dll Syncfusion.SfPdfViewer.XForms.dll Syncfusion.SfPdfViewer.XForms.Android.dll Syncfusion.SfBusyIndicator.XForms.dll Syncfusion.SfBusyIndicator.XForms.Android.dll Syncfusion.SfBusyIndicator.Android.dll Syncfusion.SfRangeSlider.XForms.dll Syncfusion.SfRangeSlider.XForms.Android.dll Syncfusion.Core.XForms.dll Syncfusion.Core.XForms.Android.dll Syncfusion.Licensing.dll Syncfusion.SfProgressBar.XForms.dll Syncfusion.SfProgressBar.XForms.Android.dll Syncfusion.SfTabView.XForms.dll Syncfusion.SfTabView.XForms.Android.dll
iOS	Syncfusion.Compression.Portable.dll Syncfusion.Pdf.Portable.dll Syncfusion.SfPdfViewer.XForms.dll Syncfusion.SfPdfViewer.XForms.iOS.dll Syncfusion.SfBusyIndicator.XForms.dll Syncfusion.SfBusyIndicator.XForms.iOS.dll Syncfusion.SfBusyIndicator.iOS.dll Syncfusion.SfRangeSlider.XForms.dll Syncfusion.SfRangeSlider.XForms.iOS.dll Syncfusion.Core.XForms.dll Syncfusion.Core.XForms.iOS.dll Syncfusion.Licensing.dll Syncfusion.SfProgressBar.XForms.dll Syncfusion.SfProgressBar.XForms.iOS.dll Syncfusion.SfTabView.XForms.dll Syncfusion.SfTabView.XForms.iOS.dll
UWP	Syncfusion.Compression.Portable.dll Syncfusion.Pdf.Portable.dll Syncfusion.SfPdfViewer.XForms.dll Syncfusion.SfPdfViewer.XForms.UWP.dll Syncfusion.SfRangeSlider.XForms.dll Syncfusion.SfRangeSlider.XForms.UWP.dll Syncfusion.SfShared.UWP.dll Syncfusion.SfInput.UWP.dll Syncfusion.Core.XForms.dll Syncfusion.Core.XForms.UWP.dll Syncfusion.Licensing.dll Syncfusion.SfProgressBar.XForms.dll Syncfusion.SfProgressBar.XForms.UWP.dll Syncfusion.SfTabView.XForms.dll Syncfusion.SfTabView.XForms.UWP.dll

NOTE

To know more about obtaining our components, refer to these links for Mac and Windows.

IMPORTANT

Starting with v16.2.0.x, if you reference Syncfusion assemblies from the trial setup or from the NuGet feed, you also have to include a license key in your projects. Please refer to Syncfusion license key to know about registering Syncfusion license key in your Xamarin application to use our components.

Creating a simple PDF Viewer application

Create a new cross platform application for Xamarin.Forms.Portable in the Visual Studio with the project name “GettingStarted” and refer the above mentioned assemblies to the respective projects.

NOTE

If you are adding the references from toolbox, this step is not needed.

An additional step is required to render the SfPdfViewer control in iOS project. You need to call the Syncfusion.SfPdfViewer.XForms.iOS.SfPdfDocumentViewRenderer.Init(), Syncfusion.SfRangeSlider.XForms.iOS.SfRangeSliderRenderer.Init() and Syncfusion.XForms.iOS.TabView.SfTabViewRenderer.Init() methods in the FinishedLaunching overridden method of the AppDelegate class after the Xamarin.Forms Framework has been initialized and before the LoadApplication is called, as demonstrated in the following code example.

C#
public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
    global::Xamarin.Forms.Forms.Init();
    Syncfusion.SfPdfViewer.XForms.iOS.SfPdfDocumentViewRenderer.Init();
    Syncfusion.SfRangeSlider.XForms.iOS.SfRangeSliderRenderer.Init();
    Syncfusion.XForms.iOS.TabView.SfTabViewRenderer.Init();
    LoadApplication(new App());
    return base.FinishedLaunching(app, options);
}

Resolving issue when deploying an application in ReleaseMode in the UWP platform

There is a known Framework issue in the UWP platform when an application using custom control is deployed in Release Mode, it will not be rendered.

This can be resolved by initializing the SfPdfViewer related assemblies in App.xaml.cs in the UWP project. Refer to the following code snippet.

C#
protected override void OnLaunched(LaunchActivatedEventArgs e)
{
     …
     rootFrame.NavigationFailed += OnNavigationFailed;
     //Add the assemblies `using System.Reflection;`
     List<Assembly> assembliesToInclude = new List<Assembly>();
     //Now, add all the assemblies that your app uses
     assembliesToInclude.Add(typeof(SfPdfDocumentViewRenderer).GetTypeInfo().Assembly);
     assembliesToInclude.Add(typeof(SfRangeSliderRenderer).GetTypeInfo().Assembly);
     assembliesToInclude.Add(typeof(Syncfusion.XForms.UWP.TabView.SfTabViewRenderer).GetTypeInfo().Assembly);
     //Replaces Xamarin.Forms.Forms.Init(e);
     Xamarin.Forms.Forms.Init(e, assembliesToInclude);
     …
}

Loading a PDF using MVVM binding

File handling with Xamarin.Forms can be done using embedded resources or writing against the native filesystem APIs. Please find more details in the below link:

https://developer.xamarin.com/guides/xamarin-forms/application-fundamentals/files/

Add a folder in the portable project with the name “Assets” and add the PDF document you need to display in the PDF viewer, here a PDF file named “GIS Succinctly.pdf” was used. In the properties of the PDF document set the build action property to be “Embedded Resource”.

Add a folder in the portable project with the name “ViewModel and include a class file with a name “PdfViewerViewModel” inside it. Add below code snippet in the “PdfViewerViewModel” class. Ensure to maintain the namespace as “GettingStarted”.

C#
using System.IO;
using System.Reflection;
using System.ComponentModel;

namespace GettingStarted
{
    class PdfViewerViewModel : INotifyPropertyChanged
    {
        private Stream m_pdfDocumentStream;

        /// <summary>
        /// An event to detect the change in the value of a property.
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// The PDF document stream that is loaded into the instance of the PDF viewer. 
        /// </summary>
        public Stream PdfDocumentStream
        {
            get
            {
                return m_pdfDocumentStream;
            }
            set
            {
                m_pdfDocumentStream = value;
                NotifyPropertyChanged("PdfDocumentStream");
            }
        }

        /// <summary>
        /// Constructor of the view model class
        /// </summary>
        public PdfViewerViewModel()
        {
            //Accessing the PDF document that is added as embedded resource as stream.
            m_pdfDocumentStream = typeof(App).GetTypeInfo().Assembly.GetManifestResourceStream("GettingStarted.Assets.GIS Succinctly.pdf");
        }

        private void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }  
    }
}

Add the following XAML code in the MainPage.xaml in the portable project.

Includes the necessary namespace where the control class resides
Set BindingContext of ContentPage to PdfViewerViewModel
Includes PDF Viewer into the page
Binds InputFileStream property of PDF Viewer control to PdfDocumentStream property of PdfViewerViewModel

XAML
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:GettingStarted"
             x:Class="GettingStarted.MainPage"
             xmlns:syncfusion="clr-namespace:Syncfusion.SfPdfViewer.XForms;assembly=Syncfusion.SfPdfViewer.XForms">
    <ContentPage.BindingContext>
        <local:PdfViewerViewModel></local:PdfViewerViewModel>
    </ContentPage.BindingContext>
    <Grid x:Name="pdfViewGrid">
        <syncfusion:SfPdfViewer x:Name="pdfViewerControl" InputFileStream="{Binding PdfDocumentStream}"/>
    </Grid> 
</ContentPage>

The sample that illustrates loading a PDF in MVVM binding can be downloaded from the link below.

https://www.syncfusion.com/downloads/support/directtrac/general/ze/GettingStarted-2072455774

On executing the above sample, you will get the output as shown in the following image.

SfPdfViewer

Loading a PDF in code-behind/programmatically

In code-behind a PDF can be loaded to PdfViewer just by using the LoadDocument method without the need of the “PdfViewerViewModel” class described in the previous section. Use the following code snippet in the code-behind of the XAML page.

C#
namespace GettingStarted
{
    public partial class MainPage : ContentPage
    {
        Stream fileStream; 
        public MainPage()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
            fileStream = typeof(App).GetTypeInfo().Assembly.GetManifestResourceStream("GettingStarted.Assets.GIS Succinctly.pdf");
            //Load the PDF
            pdfViewerControl.LoadDocument(fileStream);
        }
    }
}

In the XAML code described in the previous section, remove the binding of InputFileStream property of SfPdfViewer and the BindingContext of the page.

XAML
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:GettingStarted"
             x:Class="GettingStarted.MainPage"
             xmlns:syncfusion="clr-namespace:Syncfusion.SfPdfViewer.XForms;assembly=Syncfusion.SfPdfViewer.XForms">
    <Grid x:Name="pdfViewGrid">
        <syncfusion:SfPdfViewer x:Name="pdfViewerControl" />
    </Grid> 
</ContentPage>

The sample which illustrates loading a PDF in code-behind using LoadDocument method can be downloaded from the link below.

https://www.syncfusion.com/downloads/support/directtrac/general/ze/GettingStarted-81946798

Loading a PDF from an URL

PDF documents can be loaded from a given URL into the PdfViewer by downloading the PDF and then loading the stream of the downloaded file into the PdfViewer. In the following code sample, the HttpClient.GetAsync( ) method sends a GET request to the specified Uri as an asynchronous operation and the HttpContent.ReadAsStreamAsync( ) method will serialize the HTTP content and returns a stream that represents the content as an asynchronous operation. Finally, the obtained stream is passed to the LoadDocument( ) method of SfPdfViewer.

C#
HttpClient httpClient = new HttpClient();
HttpResponseMessage response = await httpClient.GetAsync("https://www.syncfusion.com/downloads/support/directtrac/general/pd/GIS_Succinctly1774404643.pdf");
Stream pdfStream = await response.Content.ReadAsStreamAsync();
pdfViewerControl.LoadDocument(pdfStream);

The sample that illustrates loading a PDF from an URL can be downloaded from the link below,

https://www.syncfusion.com/downloads/support/directtrac/general/ze/LoadPDFFromURL-1204672622.zip

NOTE

An Internet connection is necessary to get the stream from an URL. Please ensure that the device has a proper internet connection before running the sample application.

Loading a PDF asynchronously

Xamarin PDF Viewer allows you to load the PDF document from the specified stream asynchronously using the LoadDocumentAsync method. You can also cancel the asynchronous PDF loading when it is in progress.

C#
pdfViewerControl.LoadDocumentAsync(documentStream, cancellationTokenSource);

In the above code sample, documentStream is a stream that contains the data of the PDF document and the cancellationTokenSource enables you to cancel the asynchronous PDF loading.

Cancel the asynchronous PDF Loading

You can raise cancel request when the asynchronous load is in progress.

C#
private void cancelButton_Clicked(object sender, EventArgs e)
{
     cancellationTokenSource.Cancel();
}

In the above code sample, the cancellationTokenSource instance is the same as the one given as the argument when loading the PDF asynchronously.

NOTE

Calling the above method will not have any effect once the PDF has completely loaded. It will stop the loading process only when it is in progress.

Detect the cancellation of the PDF load

The cancellation of the PDF load operation can be detected by registering an event handler on the Token property of the CancellationTokenSource instance.

C#
EventArgs e = new EventArgs();
cancellationTokenSource.Token.Register(() => LoadDocumentAsyncCancelled(this, e));
private void LoadDocumentAsyncCancelled(object sender, EventArgs e)
{
    // handle the cancellation event
}

Unloading PDF document from the Viewer

The SfPdfViewer control allows you to unload the PDF document from the viewer, when the PDF document is not in use anymore. This releases the PDF document and all its associated resources of the application.

You need to call the Unload method of SfPdfViewer control as in the below code snippet to achieve the same.

C#
//Unloads the PDF document from the PDF viewer, freeing all the accessed resources.
pdfViewerControl.Unload();

Saving a PDF document

The SaveDocument method returns the PDF document along with the changes made (annotations addition and modification) as a stream, which can be saved as a file.

C#
//Save the PDF document
Stream pdfDocumentStream = pdfViewerControl.SaveDocument();

Please refer here for saving the PDF document as a file in the application level from the obtained stream.

NOTE

The SaveDocument method does not save the existing stamp annotations in the PDF document. Instead, use the SaveDocumentAsync method to save them.

Saving a PDF document asynchronously

The PDF Viewer also allows you to save and return the PDF document with the changes as a stream asynchronously using the SaveDocumentAsync method.

C#
//Save the PDF document asynchronously 
Task<Stream> pdfDocumentStream = pdfViewerControl.SaveDocumentAsync();

Events to track the loading and saving of PDFs

The SfPdfViewer control allows you to track the loading and saving of PDFs using the following events.

Document loaded event

The DocumentLoaded event triggers after the document is properly loaded in the SfPdfViewer. The following code example explains the same.

XAML
<syncfusion:SfPdfViewer x:Name="pdfViewerControl" DocumentLoaded="pdfViewerControl_DocumentLoaded"/>

C#
private void PdfViewerControl_DocumentLoaded(object sender, EventArgs args)  
{  

        // Get the total page count of the loaded PDF document. 
        int pageCount = pdfViewer.PageCount; 

}

Document load failed event

The UnhandledConditionOccurred event triggers when document loading fails in the SfPdfViewer. That is:

When any corrupted document is loaded.
When any non-PDF document is loaded.
The UnhandledConditionEventArgs will return the Title and Description message for the failure reason and the Handled option to enable or disable the default error alert view.

You can prevent displaying the default error alert view by setting the Handled value to true. The default value of Handled is false.

The following code example explains the same.

XAML
<syncfusion:SfPdfViewer x:Name="pdfViewerControl" UnhandledConditionOccurred="pdfViewerControl_UnhandledConditionOccurred"/>

C#
private void pdfViewerControl_UnhandledConditionOccurred(object sender, UnhandledConditionEventArgs args)  
{  

            //Set the Handled value as "true" to indicate that the event is handled in the application and to prevent the default alert view. 
            args.Handled = true; 

            // Get the title of the unhandled condition. 
            string title = args.Title; 

            // Get the details of the unhandled condition. 
            string description = args.Description; 

            DisplayAlert(title, description, "OK"); 

}

Document save initiated event

The DocumentSaveInitiated event will be triggered when the document is saved in the SfPdfViewer. The DocumentSaveInitiatedEventArgs will return the saved document stream. The following code example explains the same.

XAML
<syncfusion:SfPdfViewer x:Name="pdfViewerControl" DocumentSaveInitiated="pdfViewerControl_DocumentSaveInitiated"/>

C#
private void PdfViewerControl_DocumentSaveInitiated(object sender, DocumentSaveInitiatedEventArgs args)  
{  
      //Returns the save stream. 
      Stream saveStream = args.SaveStream; 
}

How to dispose the managed resources of SfPdfViewer

The SfPdfViewer control allows you to dispose the managed resources which are associated with the viewer. You need to call the Dispose method of the SfPdfViewer control as shown in the following code sample to achieve the same.

C#
//Disposes all the managed resources of SfPdfViewer
pdfViewer.Dispose();

How to clear the undo and redo stack

The SfPdfViewer control allows you to clear the undo and redo stacks that contain the changes that are made to the annotations in the PDF document, by calling the ClearUndoRedoStack API. When this method is called, the CanUndo and CanRedo properties will be set to false.

C#
//To clear the undo and redo stack 
pdfViewer.ClearUndoRedoStack();

How to get & set the current page number?

PDF viewer has a BindableProperty “PageNumber” using which the current page number can be retrieved and it can be set.

XAML
<Entry Keyboard="Numeric" FontSize="18" x:Name="pageNumberEntry" HorizontalTextAlignment="Center" VerticalOptions="Center" Text="{Binding PageNumber, Source={x:Reference Name=pdfViewerControl}}"/>

On binding the Entry control to PageNumber property of the PDF viewer instance, the number of the current page being displayed in the PDF viewer will be displayed in the Entry control and the PDF viewer would navigate to the page number being entered in the same.

How to get the total page number?

PDF viewer has a BindableProperty “PageCount” using which the total number of pages in the document can be retrieved.

XAML
<Label x:Name="pageCountLabel" FontSize="18" VerticalTextAlignment="Center" HorizontalTextAlignment="Center" HorizontalOptions="FillAndExpand" VerticalOptions="Center" Text="{Binding PageCount, Source={x:Reference Name=pdfViewerControl}}"/>

On binding the Label to PageCount property of the PDF viewer instance, the total number of pages in the document can be displayed.

How to navigate to next page and previous page?

PDF viewer has “GoToNextPageCommand” and “GoToPreviousPageCommand” which will navigate to the next page and previous page respectively.

XAML
<Button x:Name="goToNextButton"  Grid.Column="3" BackgroundColor="Transparent" Image="PageDown.png" HorizontalOptions="Center" VerticalOptions="Center" Command="{Binding GoToNextPageCommand, Source={x:Reference Name=pdfViewerControl}}"/>
<Button x:Name="goToPreviousButton" Grid.Column="4" BackgroundColor="Transparent" Image="PageUp.png" HorizontalOptions="Center" VerticalOptions="Center" Command="{Binding GoToPreviousPageCommand, Source={x:Reference Name=pdfViewerControl}}"/>

If the current page is already the last page of PDF document, then GoToNextPageCommand does not have any effect. Similarly, If the current page is already the first page of PDF document, then GoToPreviousPageCommand does not have any effect.

How to detect a page change?

PDF viewer has PageChanged event, which helps detecting changes in the page being displayed in the viewer.

XAML
<syncfusion:SfPdfViewer x:Name="pdfViewerControl" Grid.Row="1" PageChanged="pdfViewerControl_PageChanged"/>

C#
private void pdfViewerControl_PageChanged(object sender, Syncfusion.SfPdfViewer.XForms.PageChangedEventArgs args)
{
    int currentPageNumber = args.PageNumber;
}

The arguments of the PageChanged event contains details about to which page the document is navigated to.

How to lock or unlock all the annotations?

To lock or unlock all the annotations in a PDF, set the SfPdfViewer.AnnotationSettings.IsLocked API to true or false respectively. The default value of the API is false, and when it is set to true, annotations can be selected, but resizing, moving, editing, and removing actions will be disabled. Only the tapped and selected events from the annotations will be raised. The following code sample explains the same.

C#
//Lock all the annotations
pdfViewerControl.AnnotationSettings.IsLocked = true;

NOTE

The lock operation can also be enabled or disabled for a particular annotation type such as shape, free text, text markup, etc. Please find the code samples to enable or disable interaction for particular annotation from their respective sections.

Customize the locked annotations selection border color

By default, the selection border color for the locked annotations will be gray. You can customize the locked annotations selection border color by setting the required color to the LockedStrokeColor property. The following code illustrates the same:

C#
//Set the selection border color for the locked annotations
pdfViewerControl.AnnotationSettings.Selector.LockedStrokeColor = Color.Red;

NOTE

It is not recommended to set both the StrokeColor and LockedStrokeColor properties with the same color.

How to Change the Color of the Annotation Selector?

By default, the selection border color for the annotations will be blue. Customize the selection border color of the annotations by setting the required color to the StrokeColor property. The following code example illustrates the same.

C#
//Set the selection border color for the annotations.
pdfViewerControl.AnnotationSettings.Selector.StrokeColor = Color.Orange;

How to Customize the Annotation Selector Padding?

By changing the value of the Padding property, adjust the spacing between the annotation and the selector, which ranges from -20 to 20. The default padding between the annotation and the selector is 10. The following code example explains the same.

C#
//Set the Annotations selector padding.
pdfViewerControl.AnnotationSettings.Selector.Padding = 15;

NOTE

This property only applies to bounds-based annotations such as rectangle, circle, free text, ink, handwritten, and custom stamp annotations.

How to enable or disable the annotation selection?

To enable or disable the annotation selection, set the SfPdfViewer.AnnotationSettings.Constraints API to AnnotationConstraints.Selectable or ~AnnotationConstraints.Selectable respectively. Annotations will be selected by default, and when this API is set to ~AnnotationConstraints.Selectable, annotation selection, moving, resizing, removing and attribute changes will be disabled. Only the tapped events of the annotations will be raised. The following code sample explains the same.

C#
//Disable the selection of all annotation types.
pdfViewerControl.AnnotationSettings.Constraints = ~AnnotationConstraints.Selectable;

NOTE

The selection operation can also be enabled or disabled for a particular annotation type such as shape, free text, text markup, etc. Please find the code samples to enable or disable interaction for particular annotation from their respective sections.

How to get and set the zoom for SfPdfViewer?

PDF viewer has the BindableProperty ZoomPercentage that is used to retrieve and set the current zoom factor.

XAML
<Entry Keyboard="Numeric" FontSize="18" x:Name="zoomPercentage" HorizontalTextAlignment="Center" VerticalOptions="Center" Text="{Binding ZoomPercentage, Source={x:Reference Name=pdfViewerControl}}"/>

On binding the entry control to ZoomPercentage property of the PDF viewer instance, the current zoom percentage being displayed in the PDF viewer is displayed in the entry control, and the PDF viewer would be zoomed based on the value entered.

How to get and set Horizontal and Vertical Offsets in PDF Viewer?

Navigate to the specified vertical and horizontal offset values in PDF Viewer using ScrollToOffset (HorizontalOffset and VerticalOffset) methods and you can also retrieve the current horizontal and vertical offset position by using HorizontalOffset and VerticalOffset properties respectively in SfPdfViewer class.

C#
//Retrieves the current horizontal offset of the PdfViewerControl
m_currentHorizontalOffset = pdfViewerControl.HorizontalOffset;
//Retrieves the current vertical offset of the PdfViewerControl
m_currentVerticalOffset = pdfViewerControl.VerticalOffset;
//Scrolls the content to the specified vertical offset position in the PdfViewerControl
pdfViewerControl.ScrollToOffset(m_currentHorizontalOffset+10, m_currentVerticalOffset+10);

How to modify the width of the vertical scrollbar in the UWP platform?

The PDF viewer uses the ScrollViewer control to scroll the pages of the PDF. The width of the vertical scrollbar of the ScrollViewer can be modified by using the VerticalScrollBarWidth property. The default value of the API is the default width of the ScrollViewer control.

C#
//Sets the width of the vertical scrollbar in the PDF Viewer.
pdfViewerControl.VerticalScrollBarWidth = 50;
//Gets the width of the vertical scrollbar in the PDF Viewer.
int verticalScrollBarWidth = pdfViewerControl.VerticalScrollBarWidth;

NOTE

This API is only applicable for UWP desktop. Changing the value of this API does not affect Android and iOS devices.

How to get the list of annotations present in the PDF?

By using Annotations property, You can get the list of annotations present in the PDF document.
Refer the following code sample.

C#
//Gets the list annotations present in the PDF
var annotations = pdfViewer.Annotations;

NOTE

The list remains empty if the PDF does not have any pre-existing annotations.

Rendering the appearance content of annotations

By default, the PDF Viewer does not render the appearance content of annotations. But the appearance can be rendered by flattening the annotations before loading the PDF. This can be achieved by setting the Flatten API to true. The default value of the API is set to false.

C#
//Sets a value whether the annotations should be flattened when the PDF is loaded or not.
pdfViewerControl.AnnotationSettings.Flatten = true;
//Loads the PDF. 
pdfViewerControl.LoadDocument(stream);

NOTE

Annotations are only flattened when the page displayed in the viewer is only for viewing the appearance of annotations. Once the annotations are flattened, the interactions such as select, edit, resize, and remove cannot be performed. Setting the Flatten property to true will does not affect the save and annotation export operations. The annotations will not be flattened in these operations.

NOTE

You can also explore our Xamarin.Forms PDF Viewer example to knows the functionalities of each feature.