Friday, November 30, 2012

WPF 4.5: Airspace problem solved(...or not)

The airspace problem was one of the most annoying issues when integration a Win 32 component(like WinForms) with WPF. The problem is that each render technology belongs to only one airspace only. So when you place Win32 components in your WPF application they behave as a black hole for input leading to all kind of issues.
I blogged about this issue before and even showed a possible workaround.
With WPF 4.5 the issue is finally solved!
To do this 2 extra properties are added to the HwndHost class(the base class for WindowsFormsHost): IsRedirected and CompositionMode.
  • IsRedirected: Set this property to true to solve the airspace problem. (It’s not enabled by default.)
  • CompositionMode: Specified how deep the integration should go. It has multiple possible values:
    • None: this is the default behavior and no integration is done: the airspace problems are still here.
    • OutputOnly: The airspace problem are solved but the user (and the input system) can’t interact with the hosted win32 component.
    • Full: the airspace problems are solved and interaction with the win32 component is possible.
Remark: These two properties have to be set before any rendering is done otherwise an exception will be thrown.

Remark 2: Someone mentioned in the comments that this feature is removed in the final version of .NET 4.5. I double checked it and indeed I couldn't find it :-(

On the MSDN forums I found the following info from the .NET 4.5 Beta Readme - http://go.microsoft.com/fwlink/?LinkId=237569

1.3.10 Windows Presentation Foundation (WPF)

1.3.10.1 HwndHost feature has been removed from WPF in the .NET Framework 4.5 Beta
The .NET Framework 4.5 Developer Preview included a WPF HwndHost redirection feature. However, this feature had several known issues and has been removed from the .NET Framework 4.5 Beta. It will not be included in any future releases.
To resolve this issue:
No workaround is available.

1 comment:

Unknown said...

From all I can see, those properties were in the Beta but never made it to the final release. So the airspace problem still persists.

Please don't shoot the messenger!