Add Page automatically, remove from None automatically

[heaths]

When the SDK is "Microsoft.NET.Sdk.WindowsDesktop", it would be nice not to have to add <UseWPF>true</UseWPF>. Especially when migrating projects from old-style .csproj files, this is easy to forget and seems otherwise unnecessary since I already claimed what project type I'm going to build. And wouldn't this be true of both WPF and UWP projects anyway - to include *.xaml files as <Page> items?

Also, why must the IDE - or, when using VSCode, we (manually) - add <None Remove="..."/> when the targets could do this for any <Page> items. Could this also be done automatically in the targets for "Microsoft.NET.Sdk.WindowsDesktop"?

This could make WPF SDK-style .csproj files as slim as non-WPF SDK-style .csproj files.

[stevenbrix]

My initial thought is that WinForms applications also reference the Microsoft.NET.Sdk.WindowsDesktop, so it's possible that is needed to help differentiate. @ryalanms is more familiar with the build then I am, and can probably help understand if this is is something we control, or if it's more suited for a repo like Microsoft/MSBuild

[vatsan-madhavan]

/cc @nguerrera, @ericstj, @dsplaisted, @merriemcgaw

There are namespace overlaps between WPF & WinForms. Enabling both sets of references by default would likely cause some confusion (for both porting scenarios as well as new projects) rather than acting as a convenience.

Why would you need <None Remove="..."/> for Page items? Who or what are including them to None items in the first place that necessitates removal ? We have the ability to add something like this to the targets, as long as we are sure this is the right design to incorporate.

[heaths]

WinForm applications likely wouldn't have .xaml files, though. So maybe <UseWPF> is still required otherwise, but why not still add .xaml files to <Page> automatically?

As for adding <None>, Visual Studio does this whenever you add a new Page item. I supposed it's not specifically required, but then why is Visual Studio choosing to do it?

[weltkante]

WinForm applications likely wouldn't have .xaml files

I disagree, classic WinForms projects will default to compiling xaml as WPF <Page> if you add them, they never had any problem with that, you don't need a WPF project for adding WPF controls to your WinForms project.

In fact most of our projects are classic WinForms projects and still have WPF controls in them, works just fine. Whatever makes "WPF projects" special isn't needed in the classic project system. I don't see why that needs to change for .NET Core.

That said I don't mind flipping on a "UseWPF" switch if its required to get things working, more of an annoyance than a roadblock.

[dsplaisted]

FYI @davkean

[heaths]

@weltkante but then doesn't that mean that the WindowsDesktop SDK should put all .xaml files into a <Page> unconditionally then? When used in a WinForms app, wouldn't they still have to be compiled into pages/controls?

[weltkante]

@heaths yes that's what happens in classic projects, you can add WPF Controls to WinForms apps without switching the project type or having to adjust build tags at all (only need to add references to the WPF framework assemblies if you don't have them, gets done automatically if you use the context menu to add a new WPF item from template instead of an existing from disk). I don't think its uncommon if you are gradually making use of WPF features in your WinForms application (instead of rewriting it from scratch in WPF only)

Actually, do you manually reference framework assembly in .NET Core or does <UseWPF> pull those in? I'm used to manage them manually and don't have a VS with me right now to verify how it works in .NET Core. If the tag is responsible for adding the references I'd see why you need it, you wouldn't want WPF references in a WinForms only app, and compiling XAML without references doesn't work (the generated code references APIs from the framework after all).

After considering that I still think I'd prefer a compile error when adding xaml to WinForms without having the right references, so I think they should always compiled as Page. If anything leave the automatic inclusion off for WinForms only apps (so it doesn't pick up xaml in the folder structure and I only get compile errors if I add it manually). Adding it as None for WinForms seems wrong to me because it is never useful.

[heaths]

No, not specifying <UseWPF>true</UseWPF> still builds, but I have to add the <Page> items myself in that case, hence the ask here: just adding .xaml files to <Page> automatically.

[vatsan-madhavan]

ok, I'm confused.

Is the Issue about <Page> or about <None>? or both?

As for adding , Visual Studio does this whenever you add a new Page item. I supposed it's not specifically required, but then why is Visual Studio choosing to do it?

What are the semantics of <None>? Exactly how did this break your workflow ?

When a project implies UseWpf != true, then WPF specific semantics (like Page globbing) aren't enabled - this is by design.

[wjk]

@vatsan-madhavan I think what @heaths is referring to is the glob for <None>. It includes all files not in bin or obj, or included in another rule; this includes XAML files. Although the WindowsDesktop SDK removes Page items from None, Visual Studio might also be adding a pointless <None Remove="something.xaml" /> line to the csproj when a XAML file is added through the New Item dialog. If so, then this is a project system bug, not a WPF bug.

[vatsan-madhavan]

@wjk - thanks for puzzling that out - very helpful!

[vatsan-madhavan]

@heaths, we have talked about adding a suppressible warning when Microsoft.NET.Sdk.WindowsDesktop is in use, and neither UseWpf nor UseWinForms is set to true.

Don't have an issue tracking this yet, but I've come across several instances confusion - either missing UseWpf when using Microsoft.NET.Sdk.WindowsDesktop, or attempting to use UseWpf with Microsoft.NET.Sdk. In fact, the latter problem seems anecdotally more prevalent.

Maybe we need two changes -

• A suppressible warning in Microsoft.NET.Sdk.WindowsDesktop indicating when neither UseWpf nor UseWinForms is set to true
• A suppressible warning in Microsoft.NET.Sdk indicating when UseWpf or UseWinForms is being set to true despite the lack of support for those flags (i.e., not having imported Microsoft.NET.Sdk.WindowsDesktop targets).

@nguerrera, thoughts?

[nguerrera]

@dsplaisted @davkean are discussing related things. I'll defer to them on this.