Scroll a WPF FlowDocumentScrollViewer from code?

Question

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

I've faced a similar problem: I wanted a textual area which could hold my text, is able to wrap it, it fills its parent control and is scrollable.

First I've tried to use a TextBlock with a ScrollViewer and I think it worked, but for some reason I've wanted to use a FlowDocument instead with a FlowDocumentScrollViewer. This latter didn't work and I just couldn't leave the fight unattented so I tried to find solutions and this is how I got here. I've tried to apply the workarounds presented in the answers to the original question, however neither solutions worked out for me (I'm using .NET 4.5, maybe it works in other versions, but I don't know about that).

I've tried using a single FlowDocument by itself also, but the control contains some UI elements I didn't want. So, I came up with another solution.

  <ScrollViewer VerticalScrollBarVisibility="Auto">
    <FlowDocumentScrollViewer HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden">
      <FlowDocument>

That's right. It works! Calling ScrollViewer.ScrollToBottom() just works! The ScrollViewer enables scrolling and FlowDocumentScrollViewer removes the UI elements from the FlowDocument. Hope it helps!

---

Apparently my construction had a flaw, because this way the FlowDocument isn't scrollable via a mouse's scrolling wheel. However setting the FlowDocumentScrollViewer control's IsHitTestVisible property to False solves this.

Answer 2

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;
     }
  }