Weird scrollbar UI in hosted WPF composite control

Question

My windows forms application hosts AvalonEdit (the composite WPF control in question) in one of its forms to cater to its text editing requirements. Here's the code I use:

WPFHost = gcnew ElementHost();
TextField = gcnew AvalonEdit::TextEditor();
WPFHost->Dock = DockStyle::Fill;
WPFHost->Child = TextField;

TextField->Options->AllowScrollBelowDocument = false;
TextField->Options->EnableEmailHyperlinks = false;
TextField->Options->EnableHyperlinks = true;
TextField->Options->RequireControlModifierForHyperlinkClick = true;
TextField->ShowLineNumbers = true;

ContainerControl->Controls->Add(WPFHost); // the container is a panel

The code compiles and executes fine, except for the scrollbars - http://dl.dropbox.com/u/2584752/avalonEditBug.png . Right clicking on what's left of the bar raises an ArgumentOutOfRange exception.

Strangely, I wasn't able to reproduce the issue when I tried hosting the control in a newly created sample project. 'mI using the latest build of the text editor and have all the requisite assemblies installed.

EDIT: Wrapping the editor in a usercontrol doesn't help either.

Answer 1

This looks like a layout error to me. Maybe WPFHost measures the TextField unexpectedly.

I can suggest setting specific Width and Height on the TextField itself. If this fixes the problem you can adjust those as the size of the WPFHost control changes or try setting the MaxHeight/Width, sometimes they help and save some code for Width/Height updates.

Answer 2

try to create a WPF grid as a child of ElementHost, and place the editor inside that grid. On Other way, is to create an UserControl have the editor in that control and use the control inside your Winform app. Such approach helped me a couple of times.

Answer 3

You say that the control works fine in a new/blank project but fails in the one you need makes me wonder about conflicts more than anything. In the project you're really wanting compared to the project it worked in what are the differences? .NET version? Referencing an assembly from a directory in one but out of the GAC in another?

It's hard to say that the control is messing up for you when you've got it working elsewhere, so the only thing I can suggest is just dive deep into the differences of the two projects.

Good luck.

Answer 4

I've implemented a workaround for the issue as mentioned in this thread [ Synchronizing a WPF ScrollViewer with a WinForms ScrollBar ].