Use StaticWebAssets v2 w/ MauiAssets

[Eilon]

This should be the final piece of the puzzle for preview 7: Getting Static Web Assets v2 to work with MauiAssets on all platforms.

This system enables using all the standard Blazor features available to Blazor devs to do with static assets, including scoped CSS, on all platforms. Static Web Assets (SWA) gathers all the metadata and the Blazor Desktop targets process that and convert it to MAUI assets. MAUI assets does platform-specific logic to get the assets delivered to the target device. Then at runtime Blazor Desktop has platform-specific logic to read the files back so that they can be served in the BlazorWebView control.

There is a breaking change for Blazor Desktop apps with .NET MAUI:

• In Startup.cs do not pass in an assembly to RegisterBlazorMauiWebView() because it's not needed. Just call RegisterBlazorMauiWebView() (no parameters).

NOTE: Confirmed working on Android and WinUI; testing iOS/MacCatalyst right now.

[Eilon]

If I change the SDK of the "head" projects from the Razor SDK to just NetSDK, the static web asset error goes away, build succeeds, but the project still has no static assets.

E.g. this file: https://github.com/dotnet/maui/blob/main/src/Controls/samples/Controls.Sample.MacCatalyst/Maui.Controls.Sample.MacCatalyst-net6.csproj#L1

They really shouldn't need to be Razor SDK to begin with.

[mattleibow]

Looking pretty good. Just got a few Qs on future-proofing things.

[mattleibow]

Just a note this is quite heavy, especially if this is a large file. Since it probably will never be called, it is not essential. However, this might be worth reading via a buffer of say 4K and then just keep reading into that.

var buffer = ArrayPool<byte>.Shared.Rent(4096);
long length = 0;
while (length != (length += source.Read(buffer))) {
	// loop
}
ArrayPool<byte>.Shared.Return(buffer);

[Eilon]

Will update. I wish on Android there was a legit way to do this. You can't access the file system, calling AssetManager.OpenFd() isn't supported with compressed assets (which by default everything is), so you can get only a stream, and count the bytes as they flow by into nothingness :(

[mattleibow]

Just a note that this maybe should be a constant for now. I know there might be plans to make the images and assets go to other folders instead of just Assets. With Android, there is no choice, but since Windows might allow it, there is always someone that just has to use another folder.

Also, would this generally be configurable for all platforms because it may be the case that someone wants to put the web assets in Assets\wwwroot, and then have other, non-web stuff in Assets\Music?

[mattleibow]

However, this is more for a later PR. Not sure about the desired configurability.

[Eilon]

So ideally I would love there to be a runtime MauiAssets type that could do this for me. Was there ever any discussion on some kind of MauiAsset.GetItem(string path) that would work on all platforms?

[Eilon]

cc @Redth for this too.

[mattleibow]

One difference in the two items is the SourceType: Project vs SourceType: Discovered

Is the app project searching through all dependencies? If this is a MauiAsset, it might be because we actually do that and check dependencies and collect them all. This is how we get a MauiImage to work when it is added to the shared project and not the head projects.

How does the razor class library bundle the resources it needs for sharing? Is it embedded?

[campersau]

Suggested change

	internal sealed class iOSMauiAssetFileProvider : IFileProvider
	internal sealed class IOSMauiAssetFileProvider : IFileProvider

So it is similar to IOSWebViewManager?

[Eilon]

@campersau this file is for serving static assets such as index.html, CSS, PNG, JS, etc. within the BlazorWebView. The WebViewManager calls into this file provider to get the contents of the files.

[Eilon]

OK pushed a change from @javiercn that should fix the issue. The MSBuild targets that run are a bit different in single-project vs. multi-project.

[javiercn]

Looks great!

[Eilon]

@mattleibow said:

How does the razor class library bundle the resources it needs for sharing? Is it embedded?

Nothing embedded. It's all done via a few... thousand... lines of MSBuild 😄 It runs targets in each project to gather the resources and it has custom manifest files that it uses to track what file came from where. Then with more MSBuild it processes those manifests to figure out what needs to be converted to a MauiAsset.