External library method doesn't work with IL2CPP backend

I'm not too familiar with this library, but in general this should work.

If you are including the PDFSHarp code as a separate .dll in your project (a managed plug-in), I would recommend disabling managed code stripping for it. See https://docs.unity3d.com/Manual/IL2CPP-BytecodeStripping.html for details.

Many library don't work well with managed code stripping. Managed code stripping is enable for IL2CPP, but disabled for Mono by default. So that might account for the difference in behavior.

 

I don't believe that this is the same as that issue you linked to.

In general, I would avoid using System.Drawing.dll. It depends on OS-specific code, and Unity does not support it. As for the specific issue, I suspect that it is a problem with System.Drawing.dll, but if you would like to submit a bug report, we can take a closer look.

 

With IL2CPP you can prevent managed code stripping on the level of a specific assembly, namespace, type, or method using in the link.xml file. See the Link XML section in the documentation at https://docs.unity3d.com/Manual/ManagedCodeStripping.html for details about how to do that.

 

We don't have anything officially documented. But there are some crude diagnostics that can be turned on.

I mentioned how to turn on diagnostics in https://forum.unity.com/threads/il2...tal-player-build-failed.1249945/#post-8423187 see the part about "--enable-report --enable-snapshot"

"--enable-report" will turn on the diagnostics. "--enable-snapshot" makes the files a little easier to find.

Here are some tips that sound like they may help you.

1) When "--enable-report" is used, the Editor log will contain warnings about reflection usages that the linker could not detect.

Here is an example of what appears in the Editor log when I toss some reflection into a script.

ILLink: Trim analysis warning IL5999: .test.Start(): Unhandled reflection usage in `System.Void test::Start()` : IL_000b: callvirt System.Reflection.MethodInfo System.Type::GetMethod(System.String)

ILLink: Trim analysis warning IL2075: .test.Start(): The requirements declared via the 'DynamicallyAccessedMembersAttribute' on the return value of method 'System.Object.GetType()' don't match those on the implicit 'this' parameter of method 'System.Type.GetMethod(String)'. The source value must declare at least the same requirements as those declared on the target location it's assigned to

ILLink: warning IL5999: .test.Start(): Unhandled reflection usage in `System.Void test::Start()` : IL_000b: callvirt System.Reflection.MethodInfo System.Type::GetMethod(System.String)

This information is also output to files. In your project directory, search for a directory named "UnityLinker_Diagnostics". In there "Messages.log" and "ReflectionUsages.log" also contain information about reflection.

If you used "--enable-snapshot" then these files will also appear under the snapshot directory at "%TEMP%\UnityLinker\Snapshots\<snapshot dir>\output\UnityLinker_Diagnostics"

2) Another file that you might find useful is "SweepReport.log". This is a log of everything that was removed. It will be in the "UnityLinker_Diagnostics" directory alongside the files above.

These diagnostics are intended for internal use. They are a little rough around the edges and could change at any time. That said, they have been fairly stable since their introduction many years ago.

Hope that helps. If you have any questions let me know.