How to use the external scroll bars with WPF image viewer?

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In order to use the external scroll bars in WpfImageViewer class is necessary to:

disable standard scroll bars in WpfImageViewer class by setting the value of WpfImageViewer.AutoScroll property to false
subscribe to the WpfImageViewer.ImageLoaded event and initiale the parameters of external scroll bars when image is loaded
subscribe to the WpfImageViewer.SizeChanged event and update the external scroll bars when size of WpfImageViewer is changed
subscribe to the WpfImageViewer.ZoomChanged event and update the external scroll bars when image zoom in WpfImageViewer is changed
subscribe to the System.Windows.Controls.Primitives.RangeBase.ValueChanged event of external scroll bars and scroll the image in viewer using the WpfImageViewer.ViewerState.AutoScrollPosition property.

WpfImageViewerState class provides the following abilities for manipulating the scroll bars of WpfImageViewer:

changing the scroll bars position
obtaining size of horizontal and vertical scroll bar.

Here is C#/VB.NET code that demonstrates how to use external scroll bars with WpfImageViewer class:

public partial class WpfImageViewer_ExternalScrollBars : System.Windows.Window
{

    #region Constructors

    public WpfImageViewer_ExternalScrollBars()
    {
        InitializeComponent();
        // ...
        imageViewer.ImageLoaded += new System.EventHandler<Vintasoft.Imaging.ImageLoadedEventArgs>(imageViewer_ImageLoaded);
        imageViewer.ZoomChanged += new System.EventHandler<Vintasoft.Imaging.UI.ZoomChangedEventArgs>(imageViewer_ZoomChanged);
        imageViewer.SizeChanged += new System.Windows.SizeChangedEventHandler(imageViewer_SizeChanged);
        horizontalScrollBar.ValueChanged +=
            new System.Windows.RoutedPropertyChangedEventHandler<double>(ScrollBar_ValueChanged);
        verticalScrollBar.ValueChanged +=
            new System.Windows.RoutedPropertyChangedEventHandler<double>(ScrollBar_ValueChanged);

        imageViewer.AutoScroll = false;
        // ...
    }

    #endregion



    #region Methods

    /// <summary>
    /// Image is loaded in image viewer.
    /// </summary>
    private void imageViewer_ImageLoaded(object sender, Vintasoft.Imaging.ImageLoadedEventArgs e)
    {
        SetScrollBarsParams();
    }

    /// <summary>
    /// Image viewer size is changed.
    /// </summary>
    private void imageViewer_SizeChanged(object sender, System.Windows.SizeChangedEventArgs e)
    {
        SetScrollBarsParams();
    }

    /// <summary>
    /// Image viewer zoom is changed.
    /// </summary>
    private void imageViewer_ZoomChanged(object sender, Vintasoft.Imaging.UI.ZoomChangedEventArgs e)
    {
        SetScrollBarsParams();
    }

    /// <summary>
    /// Sets parameters of scroll bars.
    /// </summary>
    private void SetScrollBarsParams()
    {
        // initialize horizontal scroll bar
        horizontalScrollBar.Minimum = 0;
        horizontalScrollBar.Maximum = imageViewer.ViewerState.AutoScrollSize.Width;
        horizontalScrollBar.Track.ViewportSize = imageViewer.ActualWidth;

        // initialize vertical scroll bar
        verticalScrollBar.Minimum = 0;
        verticalScrollBar.Maximum = imageViewer.ViewerState.AutoScrollSize.Height;
        verticalScrollBar.Track.ViewportSize = imageViewer.ActualHeight;
    }

    /// <summary>
    /// Scroolbar is changed.
    /// </summary>
    private void ScrollBar_ValueChanged(object sender, System.Windows.RoutedPropertyChangedEventArgs<double> e)
    {
        System.Windows.Point currentPosition =
            new System.Windows.Point(horizontalScrollBar.Value, verticalScrollBar.Value);
        imageViewer.ViewerState.AutoScrollPosition = currentPosition;
    }

    #endregion

}

VB.NET

Public Partial Class WpfImageViewer_ExternalScrollBars
    Inherits System.Windows.Window

    #Region "Constructors"

    Public Sub New()
        InitializeComponent()
        ' ...
        AddHandler imageViewer.ImageLoaded, New System.EventHandler(Of Vintasoft.Imaging.ImageLoadedEventArgs)(AddressOf imageViewer_ImageLoaded)
        AddHandler imageViewer.ZoomChanged, New System.EventHandler(Of Vintasoft.Imaging.UI.ZoomChangedEventArgs)(AddressOf imageViewer_ZoomChanged)
        AddHandler imageViewer.SizeChanged, New System.Windows.SizeChangedEventHandler(AddressOf imageViewer_SizeChanged)
        AddHandler horizontalScrollBar.ValueChanged, New System.Windows.RoutedPropertyChangedEventHandler(Of Double)(AddressOf ScrollBar_ValueChanged)
        AddHandler verticalScrollBar.ValueChanged, New System.Windows.RoutedPropertyChangedEventHandler(Of Double)(AddressOf ScrollBar_ValueChanged)

            ' ...
        imageViewer.AutoScroll = False
    End Sub

    #End Region



    #Region "Methods"

    ''' <summary>
    ''' Image is loaded in image viewer.
    ''' </summary>
    Private Sub imageViewer_ImageLoaded(sender As Object, e As Vintasoft.Imaging.ImageLoadedEventArgs)
        SetScrollBarsParams()
    End Sub

    ''' <summary>
    ''' Image viewer size is changed.
    ''' </summary>
    Private Sub imageViewer_SizeChanged(sender As Object, e As System.Windows.SizeChangedEventArgs)
        SetScrollBarsParams()
    End Sub

    ''' <summary>
    ''' Image viewer zoom is changed.
    ''' </summary>
    Private Sub imageViewer_ZoomChanged(sender As Object, e As Vintasoft.Imaging.UI.ZoomChangedEventArgs)
        SetScrollBarsParams()
    End Sub

    ''' <summary>
    ''' Sets parameters of scroll bars.
    ''' </summary>
    Private Sub SetScrollBarsParams()
        ' initialize horizontal scroll bar
        horizontalScrollBar.Minimum = 0
        horizontalScrollBar.Maximum = imageViewer.ViewerState.AutoScrollSize.Width
        horizontalScrollBar.Track.ViewportSize = imageViewer.ActualWidth

        ' initialize vertical scroll bar
        verticalScrollBar.Minimum = 0
        verticalScrollBar.Maximum = imageViewer.ViewerState.AutoScrollSize.Height
        verticalScrollBar.Track.ViewportSize = imageViewer.ActualHeight
    End Sub

    ''' <summary>
    ''' Scroolbar is changed.
    ''' </summary>
    Private Sub ScrollBar_ValueChanged(sender As Object, e As System.Windows.RoutedPropertyChangedEventArgs(Of Double))
        Dim currentPosition As New System.Windows.Point(horizontalScrollBar.Value, verticalScrollBar.Value)
        imageViewer.ViewerState.AutoScrollPosition = currentPosition
    End Sub

    #End Region

End Class

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