[Skia.Gtk] Skia is looking for files that don't exist on Arm64

[bstrother1]

Current behavior

Seems like a bug. Template Net 6 Gtk is looking for specific files that might not exist on a standard installation of gtk on an ARM64 mac.

Expected behavior

Gtk to build on an arm64 mac

How to reproduce it (as minimally and precisely as possible)

-> Have a Arm64/Monterey Mac Environment
-> Install gtk+3
-> attempt to run https://github.com/unoplatform/uno/discussions/8263#:~:text=dotnet%20App.Skia.Gtk.dll
-> get System.DllNotFoundException: libgtk-3-0.dll, libgtk.so.0, libgtk-3.0.dylib, gtk-3.dll

Workaround

n/a

Works on UWP/WinUI

Yes

Environment

Other

NuGet package version(s)

Latest Net6 template

Affected platforms

macOS, Skia (GTK on Linux/macOS/Windows)

IDE

Visual Studio 2022

IDE version

17.0.7303

Relevant plugins

No response

Anything else we need to know?

This was a discussion but it seems to be a bug relating to the fix for gtk on Monterey producing different files.

[jeromelaban]

Thanks for the report. Uno is not handling this part of the loading, and is likely a GtkSharp related issue.

[spouliot]

@bstrother1 I ran into the same issue while following the getting started docs.

brew used to install stuff under /usr/local/ and GtkSharp still expect this.

https://github.com/GtkSharp/GtkSharp/blob/7995f132e19e18b8dae94359246540f059e53a86/Source/Libs/Shared/GLibrary.cs#L55

Adding DYLD_FALLBACK_LIBRARY_PATH inside my launch.json fixed this part.

      "env": {
        "DOTNET_MODIFIABLE_ASSEMBLIES": "debug",
        "DYLD_FALLBACK_LIBRARY_PATH": "/opt/homebrew/lib/"
      },

The next problem is that the native libSkiaSharp.dylib for a net5.0 project is only available as x86_64, not arm64

$ file bin/Debug/net5.0/runtimes/osx/native/libSkiaSharp.dylib                                                                                                                    bin/Debug/net5.0/runtimes/osx/native/libSkiaSharp.dylib: Mach-O universal binary with 1 architecture: [x86_64:Mach-O 64-bit dynamically linked shared library x86_64
- Mach-O 64-bit dynamically linked shared library x86_64]
bin/Debug/net5.0/runtimes/osx/native/libSkiaSharp.dylib (for architecture x86_64):	Mach-O 64-bit dynamically linked shared library x86_64

but since you mentioned using the net6 templates maybe you won't hit that similar issue.

GitHub

GtkSharp/GLibrary.cs at 7995f132e19e18b8dae94359246540f059e53a86 · GtkSharp/GtkSharp

.NET wrapper for Gtk and other related libraries. Contribute to GtkSharp/GtkSharp development by creating an account on GitHub.

[jeromelaban]

Indeed, SkiaSharp will need an arm64 build as well. One more thing to do for SkiaSharp :) It may be similar to mono/SkiaSharp#1829.

[spouliot]

@jeromelaban SkiaSharp has an arm64 build, I used it recently for a console-based project. However it is (or was) only available in pre-release nugets. c.c. @mattleibow

Sadly the Skia version, checked at runtime, is different so you can't simply copy the newer fat binary as a quick workaround for Uno on macOS/M1 :-(

I have not found (honestly I did not look very hard) where the Uno.UI.Skia.Gtk nuget sources are located, but I suspect it would not be hard to fix.

[spouliot]

Just FWI I hacked my local uno.ui.runtime.skia.gtk.nuspec to depend on the latest SkiaSharp preview available on nuget.org. Sadly there's no stable release that include the arm64 slice :(

<dependency id="SkiaSharp" version="2.88.0-preview.254" exclude="Build,Analyzers" />
<dependency id="SkiaSharp.NativeAssets.Linux" version="2.88.0-preview.254" exclude="Build,Analyzers" />

and I can now run the Gtk template/sample on my M1-based mac computer. YMMV

[bstrother1]

Just FWI I hacked my local uno.ui.runtime.skia.gtk.nuspec to depend on the latest SkiaSharp preview available on nuget.org. Sadly there's no stable release that include the arm64 slice :(

<dependency id="SkiaSharp" version="2.88.0-preview.254" exclude="Build,Analyzers" />
<dependency id="SkiaSharp.NativeAssets.Linux" version="2.88.0-preview.254" exclude="Build,Analyzers" />

and I can now run the Gtk template/sample on my M1-based mac computer. YMMV

Where can I find this file? Thanks!

[spouliot]

The exact location can vary depending on the Uno version you're using. Try the following command to locate it inside your nuget cache.

$ find ~/.nuget -name uno.ui.runtime.skia.gtk.nuspec

On my system the location returned is:

/Users/poupou/.nuget/packages/uno.ui.runtime.skia.gtk/4.1.9/uno.ui.runtime.skia.gtk.nuspec

Since I posted the workaround I noticed that the R(ed) and B(lue) channel seems inverted by Skia. That's likely something else that changed between the old 2.80 and the newer 2.88 release.

[jeromelaban]

Indeed, we've noticed something like this depending on the platforms or OS configuration maybe. We're not definitely handling it properly.

[spouliot]

depending on the platforms or OS configuration maybe

I lack a variety of platform to test, but it happens on my M1 mac. Since it's not realted t the original issue I filed a new issue for this problem: #8580