wpftouchxpsdocumentviewerxpsdocument

WPF DocumentViewer enable scroll on touch screen for XPS document


When showing an XPS document in the DocumentViewer control of a WPF application it does not allow you to scroll its content on a touch enabled tablet just my moving your fingers over the screen.

Instead it selects the text. The only way of scrolling on a touch enabled device is by using the vertical scrollbar.

Is there a way to enable touch scrolling by moving your fingers on the content itself instead of on the vertical scrollbar?

By overriding some styles I could prevent the text selection but it still does not allow me to scroll. ( https://stackoverflow.com/a/415155/187650 )


Solution

  • I had the same problem and i made a solution and it works perfectly.

    I made an own Xps Document class to set URI dynamically:

    public class ManualXpsDocument : XpsDocument
    {
        private const string _uriOfDoc= "...\\path.xps";
    
        public ManualXpsDocument(FileAccess fileAccess) : base(_uriOfDoc, fileAccess)
        {
    
        }
    }
    

    Here is the xaml part of window (or control):

      <Grid.Resources>
            <ObjectDataProvider x:Key="myDataSource" MethodName="GetFixedDocumentSequence"
                                ObjectType="{x:Type manual:ManualXpsDocument}">
                <ObjectDataProvider.ConstructorParameters>
                    <io:FileAccess>Read</io:FileAccess>
                </ObjectDataProvider.ConstructorParameters>
            </ObjectDataProvider>
        </Grid.Resources>
        <DocumentViewer  x:Name="Viewer" Document="{Binding Source={StaticResource myDataSource}}">
            <DocumentViewer.Resources>
                <Style TargetType="ToolBar">
                    <Setter Property="Visibility" Value="Collapsed" />
                </Style>
                <Style TargetType="{x:Type ContentControl}">
                    <Setter Property="Visibility" Value="Collapsed" />
                </Style>
            </DocumentViewer.Resources>
            <DocumentViewer.Style>
                <Style TargetType="{x:Type DocumentViewer}">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="{x:Type DocumentViewer}">
                                <controls:CustomScrollViewer x:Name="PART_ContentHost">
                                    <controls:CustomScrollViewer.Style>
                                        <Style TargetType="{x:Type ScrollViewer}">
                                            <Setter Property="Focusable" Value="false" />
                                            <Setter Property="IsDeferredScrollingEnabled" Value="True" />
                                            <Setter Property="Template">
                                                <Setter.Value>
                                                    <ControlTemplate TargetType="{x:Type ScrollViewer}">
                                                        <Border BorderBrush="#00000000"
                                                            BorderThickness="0,2,0,0">
                                                            <Grid Background="{TemplateBinding Background}"
                                                                 SnapsToDevicePixels="true">
                                                                <Grid.ColumnDefinitions>
                                                                    <ColumnDefinition Width="*" />
                                                                    <ColumnDefinition Width="Auto" />
                                                                </Grid.ColumnDefinitions>
                                                                <Grid.RowDefinitions>
                                                                    <RowDefinition Height="*" />
                                                                    <RowDefinition Height="Auto" />
                                                                </Grid.RowDefinitions>
    
                                                                <ScrollContentPresenter Name="PART_ScrollContentPresenter"
                                                                                            ScrollViewer.IsDeferredScrollingEnabled="True"
                                                                                            KeyboardNavigation.DirectionalNavigation="Local"
                                                                                            CanContentScroll="True" 
                                                                                            SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
    
    
                                                                <controls:CustomScrollBar Name="PART_VerticalScrollBar"
                                                                                          Style="{DynamicResource ScrollBar}"
                                                                                          Grid.Column="1"
                                                                                          Value="{TemplateBinding VerticalOffset}"
                                                                                          Maximum="{TemplateBinding ScrollableHeight}"
                                                                                          ViewportSize="{TemplateBinding ViewportHeight}"
                                                                                          Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" />
                                                                <controls:CustomScrollBar Name="PART_HorizontalScrollBar"
                                                                                          Grid.Row="1"
                                                                                          Grid.ColumnSpan="2"
                                                                                          Style="{DynamicResource ScrollBar}"
                                                                                          Orientation="Horizontal"       
                                                                                          Value="{TemplateBinding HorizontalOffset}"
                                                                                          Maximum="{TemplateBinding ScrollableWidth}"
                                                                                          ViewportSize="{TemplateBinding ViewportWidth}"
                                                                                          Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}" />
                                                            </Grid>
                                                        </Border>
                                                    </ControlTemplate>
                                                </Setter.Value>
                                            </Setter>
                                        </Style>
                                    </controls:CustomScrollViewer.Style>                                 
                                </controls:CustomScrollViewer>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </DocumentViewer.Style>
        </DocumentViewer>
    

    Here is The xaml.cs part of Window (or control):

        public ctor()
        {
            InitializeComponent();
    
            PreviewTouchMove += ScrollingHandler;
    
        }
    
        private void ScrollingHandler(object sender, TouchEventArgs e)
        {
            TouchPoint tp = e.GetTouchPoint(Viewer);
            if (tp.Action == TouchAction.Move)
            {
                //_scrollingInt is not necessary but Move procedure of Viewer has const value to scroll and the optimalization is recommended. 
                if (_lastYPosition > tp.Position.Y + _scrollingInt)
                {
                    Viewer.MoveDown();
                    _lastYPosition = tp.Position.Y;
                }  
                else if (_lastYPosition < tp.Position.Y - _scrollingInt)
                {
                    Viewer.MoveUp();
                    _lastYPosition = tp.Position.Y;
                }
            }
    
            // Viewer.IsHitTestVisible = false; this setting can disable the selection too,but if you use this, the hyperlinks won't work too.
    
            Viewer.GetType().GetProperty("IsSelectionEnabled", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(Viewer, false, null);
    
            //set false "IsSelectionEnabled" "hidden" property instead of Viewer.IsHitTestVisible = false, because the hyperlinks will work too. 
    
            e.Handled = true;
        }
    

    ScrollingHandler method solve the problem. This procedure do the scrolling of document viewer and disable the selection but the hyperlink function still available.