Question

I have a persistent problem with textboxes in WPF, using .NET 3.5. With a large (5000+ lines) amount of data in a TextBox with wrapping enabled, the window has ridiculously bad performance while being resized.

This only happens with TextWrapping=”Wrap”. Having the text data bound or just setting it programmatically makes no difference.

The code is literally as simple as this:

<TextBox Margin="12,39,337,29" Text="{Binding Output, Mode=OneWay}" TextWrapping="Wrap" VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Disabled" />

The text is bound to a single string. The bound data is not being changed.

Edit: The data is not being changed while the window is resizing, is what I meant. It will be updated in the future. The TextBox does not need to be editable, but the actual text does need to be selectable. /Edit.

I’ve had a quick play with AvalonEdit, which has the same problem. It seems strange that I can’t find any other threads which describe this issue.

Any advice?

Thanks,
Rich

Answer 1

You could react to the windowResizeStart event and disable wrapping for the text block.
Then wrap just once when the resize completes.

You gain performance but lose some visual flair I guess.