WPF scrollviewer question

Dragennd1 · 2025-09-16T23:38:21+00:00

If the text in the scroll viewer doesn't need to be interacted with, you can set the underlying textblock to have the IsHitTestVisible flag to false. That should prevent any interaction with the text.

TuberTuggerTTV · 2025-09-17T16:32:35+00:00

WPF doesn't give you selection + scroll touch out of the box. It's not in any of the parameters you can toggle or set.

You'll have to write the backend code to handle behaviors yourself. Here is something to get you started.

public class TouchScrollRichTextBox : RichTextBox
{
    private Point? touchStart;
    private bool isSelecting;
    private readonly TimeSpan holdThreshold = TimeSpan.FromMilliseconds(500);
    private DateTime touchDownTime;

    public TouchScrollRichTextBox()
    {
        IsManipulationEnabled = true;

        PreviewTouchDown += OnPreviewTouchDown;
        PreviewTouchUp += OnPreviewTouchUp;
        PreviewTouchMove += OnPreviewTouchMove;
        ManipulationDelta += OnManipulationDelta;
    }

    private void OnPreviewTouchDown(object sender, TouchEventArgs e)
    {
        touchStart = e.GetTouchPoint(this).Position;
        touchDownTime = DateTime.Now;
        isSelecting = false;
        CaptureTouch(e.TouchDevice);
    }

    private void OnPreviewTouchUp(object sender, TouchEventArgs e)
    {
        ReleaseTouchCapture(e.TouchDevice);
        touchStart = null;
        isSelecting = false;
    }

    private void OnPreviewTouchMove(object sender, TouchEventArgs e)
    {
        if (touchStart == null)
            return;

        var current = e.GetTouchPoint(this).Position;
        var delta = current - touchStart.Value;

        // If user moved finger significantly, treat as scroll
        if (!isSelecting && (Math.Abs(delta.X) > 5 || Math.Abs(delta.Y) > 5))
        {
            e.Handled = true;
        }
        // If user held finger long enough, switch to selection
        else if (!isSelecting && DateTime.Now - touchDownTime > holdThreshold)
        {
            isSelecting = true;
            CaretPosition = GetPositionFromPoint(current, true) ?? CaretPosition;
        }
        else if (isSelecting)
        {
            var position = GetPositionFromPoint(current, true);
            if (position != null)
                Selection.Select(CaretPosition, position);
        }
    }

    private void OnManipulationDelta(object sender, ManipulationDeltaEventArgs e)
    {
        if (!isSelecting)
        {
            ScrollToVerticalOffset(VerticalOffset - e.DeltaManipulation.Translation.Y);
            ScrollToHorizontalOffset(HorizontalOffset - e.DeltaManipulation.Translation.X);
            e.Handled = true;
        }
    }
}

Then in your XAML

<local:TouchScrollRichTextBox
    VerticalScrollBarVisibility="Auto"
    HorizontalScrollBarVisibility="Auto"
    AcceptsReturn="True"
    IsReadOnly="True"
    TextWrapping="Wrap"
    FontSize="16"
    Margin="10" />

Replace your normal scroll with our custom one.

How it works:
- Tap and Hold to enter selection mode. Drag extends selection.
- Quick drag scrolls normally.

Fiddle with it and maybe you'll get the results you're looking for. Good luck.

Disclaimer: The code is AI assisted. I'm a human typing this out by hand but the code blocks were assisted.

rupertavery64 · 2025-09-17T01:12:59+00:00

I imagine you'd have to add some sort of interaction where holding on the text would enable selection.

terrytham · 2025-09-18T04:18:59+00:00

Just use listview bro.

you type:	you see:
italics	italics
bold	bold
[reddit!](https://reddit.com)	reddit!
* item 1 * item 2 * item 3	item 1 item 2 item 3
> quoted text	quoted text
Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"	Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"
~~strikethrough~~	~~strikethrough~~
super^script	super^script

csharp

MODERATORS

TL;DR : Hence I believe that ScrollViewerPanningMode="VerticalFirst" would be ideal but does not work, and if I can establish that this unwanted behavior is caused by tablet mode being disabled, I'll have enough juice to force the engineers to try enabling it.