Scroll a WPF FlowDocumentScrollViewer from code?

Question

Hi,

I have a FlowDocumentScrollViewer I want to automatically scroll to the bottom when text is added.

<FlowDocumentScrollViewer Name="Scroller">
 <FlowDocument Foreground="White" Name="docDebug" FontFamily="Terminal">
  <Paragraph Name="paragraphDebug"/>
 </FlowDocument>
</FlowDocumentScrollViewer>

In code I add Inlines to the Paragraph, but when there is to much text I would like to be able to simply scroll down using code instead of having the user doing so.

Any suggestions?

Answer 1

try:

Scroller.ScrollViewer.ScrollToEnd();

Where "Scroller" is the name of your FlowDocumentScrollViewer.

EDIT: I wrote this answer a little too quickly. FlowDocumentScrollViewer does not expose a ScrollViewer property. I had actually extended the FlowDocumentScrollViewer class and implemented the ScrollViewer property myself. Here is the implementation:

  /// <summary>
  /// Backing store for the <see cref="ScrollViewer"/> property.
  /// </summary>
  private ScrollViewer scrollViewer;

  /// <summary>
  /// Gets the scroll viewer contained within the FlowDocumentScrollViewer control
  /// </summary>
  public ScrollViewer ScrollViewer
  {
     get
     {
        if (this.scrollViewer == null)
        {
           DependencyObject obj = this;

           do
           {
              if (VisualTreeHelper.GetChildrenCount(obj) > 0)
                 obj = VisualTreeHelper.GetChild(obj as Visual, 0);
              else
                 return null;
           }
           while (!(obj is ScrollViewer));

           this.scrollViewer = obj as ScrollViewer;
        }

        return this.scrollViewer;
     }
  }

Answer 2

Hi, i've tried this:

flowDocumentScrollViewer1.ScrollViewer.ScrollToEnd();

but i get "[ScrollViewer] is inaccessible due to its protection level"

:-(

Answer 3

The other answers given here are a bit puzzling, since I don't see any public "ScrollViewer" property on the FlowDocumentScrollViewer.

I hacked around the problem like this. Beware that this method can return null during initialization:

public static ScrollViewer FindScrollViewer(this FlowDocumentScrollViewer flowDocumentScrollViewer)
{
    if (VisualTreeHelper.GetChildrenCount(flowDocumentScrollViewer) == 0)
    {
        return null;
    }

    // Border is the first child of first child of a ScrolldocumentViewer
    DependencyObject firstChild = VisualTreeHelper.GetChild(flowDocumentScrollViewer, 0);
    if (firstChild == null)
    {
        return null;
    }

    Decorator border = VisualTreeHelper.GetChild(firstChild, 0) as Decorator;

    if (border == null)
    {
        return null;
    }

    return border.Child as ScrollViewer;
}