.net8 windows form design view problem.

Question

I am developing Revit addin in Vidual Studio in c++/cli as class library.

Before moving to .net platform everyhing was working fine. But in .net Windows form design views doesnt work. Though when I add form element by code. It compiles and works.

The error is:

The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file: ModelessForm --- The base class 'System.Windows.Forms.Form' could not be loaded. Ensure the assembly has been referenced and that all projects have been built.

Regarding to Windows forms I aded lines below to .vcxproj file

<WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>

<TargetFramework>net8.0-windows</TargetFramework>

<ItemGroup>

<FrameworkReference Include="Microsoft.WindowsDesktop.App" />

<FrameworkReference Include="Microsoft.WindowsDesktop.App.WPF" />

<FrameworkReference Include="Microsoft.WindowsDesktop.App.WindowsForms" /> </ItemGroup>

Instances of this error (1)

1. Hide Call Stack

at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)

at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)

at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)

at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)

This is form design view window.

The Visual Studio project file is at link below.

https://sendgb.com/U9ePtjK7T5x

Does snybody have any idea how i can resolve that problem?

Answer 1

Hi,

In Configuration Manager: add new configuration. Such as named design , used to design Winform but not compile it.

Then

Click OK. Then CTRL+S to save the project file.

Add the condition to vcxproj file reference include and framework reference

itemgroup.txt

In Design:

Since out of process does not support C++CLI. You still need to add controls' code manually, but the controls can be displayed in the designer.

Before building the project, switch to Debug or Release.

Best regards,

Minxin Yu

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Answer 2

Somehow I got it worked.

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Sample code is at the link below. c++ .net8.0 and WindowsForms work together.

https://github.com/halukuzuner/RevitAddinCppNet8.0