Implemented IVsEditorFactoryChooser on AbstractEditorFactory class to invoke WinForms designer editor factory directly by VS Shell

[Shyam-Gupta]

Implemented IVsEditorFactoryChooser interface on AbstractEditorFactory class. This interface provides a method ChooseEditorFactory which is invoked by VS Shell before CreateEditorInstance method is invoked.

ChooseEditorFactory method provides an opportunity to the current editor factory to sniff the file and return another editor factory guid if required. If an alternate editor factory guid is returned, VS Shell will invoke that editor factory directly. Else it will continue to invoke CreateEditorInstance method of current editor factory. We use this mechanism to check if rguidLogicalView is Designer. If it is designer, then ChooseEditorFactory will return editor factory guid of a new WinForms Editor Factory WinFormsDesignerEditorFactory. This new editor factory will return an instance of IAsyncDocView interface which will enable it to load the designer asynchronously.

We have safeguarded the changes behind a feature flag which will be enabled by default.

[jasonmalinowski]

@Shyam-Gupta Once this is rolled out fully, would this mean we can delete all the other code we have in our editor factory that special cases WinForms by simply always delegating to the other editor factory?

[jasonmalinowski]

I've restarted the integration test failures, but they weren't looking entirely optimistic:

Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException
   at EnvDTE.ProjectItem.Open(System.String)
   at Microsoft.VisualStudio.TemplateWizard.Wizard.OpenNotedItems(System.String, System.Collections.Generic.List`1<Microsoft.VisualStudio.TemplateWizard.WizardExtension>, EnvDTE.Project)
   at Microsoft.VisualStudio.TemplateWizard.Wizard.Execute(System.Object, IntPtr, System.Object[] ByRef, System.Object[] ByRef, EnvDTE.wizardResult ByRef)
   at Microsoft.VisualStudio.CommonIDE.Solutions.Interop.IVsNativeEnvironmentInternal.WizLoadAndRunFile(System.String, System.String, Boolean, Boolean, System.Array, System.String)
   at Microsoft.VisualStudio.CommonIDE.Solutions.Dte.DteSolution+<AddFromTemplateExAsync>d__248.MoveNext()
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].Start[[Microsoft.VisualStudio.CommonIDE.Solutions.Dte.DteSolution+<AddFromTemplateExAsync>d__248, Microsoft.VisualStudio.CommonIDE, Version=17.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a]](<AddFromTemplateExAsync>d__248 ByRef)
   at Microsoft.VisualStudio.CommonIDE.Solutions.Dte.DteSolution.AddFromTemplateExAsync(System.String, System.String, System.String, System.String, Boolean, UInt32, System.Threading.CancellationToken)
   at Microsoft.VisualStudio.CommonIDE.Solutions.Dte.DteSolution+<>c__DisplayClass247_0.<AddFromTemplateEx>b__0()
   at Microsoft.VisualStudio.Threading.JoinableTaskFactory.ExecuteJob[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]](System.Func`1<System.Threading.Tasks.Task>, Microsoft.VisualStudio.Threading.JoinableTask)
   at Microsoft.VisualStudio.Threading.JoinableTaskFactory.RunAsync[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]](System.Func`1<System.Threading.Tasks.Task`1<System.__Canon>>, Boolean, System.String, Microsoft.VisualStudio.Threading.JoinableTaskCreationOptions)
   at Microsoft.VisualStudio.Threading.JoinableTaskFactory.Run[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]](System.Func`1<System.Threading.Tasks.Task`1<System.__Canon>>, Microsoft.VisualStudio.Threading.JoinableTaskCreationOptions)
   at Microsoft.VisualStudio.CommonIDE.Solutions.Dte.DteSolution.AddFromTemplateEx(System.String, System.String, System.String, System.String, Boolean, UInt32)

So that could be related to a crash in the editor factory since it was trying to open a file.

[Shyam-Gupta]

@Shyam-Gupta Once this is rolled out fully, would this mean we can delete all the other code we have in our editor factory that special cases WinForms by simply always delegating to the other editor factory?

Yes thats right. Once it all works as expected, I will share another PR to cleanup that code.

[Shyam-Gupta]

I've restarted the integration test failures, but they weren't looking entirely optimistic:

Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException

So that could be related to a crash in the editor factory since it was trying to open a file.

Its happening because the VS build against which integration tests are running does not have WinForms inproc designer side of changes yet. To workaround this issue, I have set defaultValue = false for the feature flag. This way the tests will use earlier code path which doesn't utilize the new editor factory. It will use the new EF once the change gets inserted into VS.