Libraries leptonica link name not present

[Genko71]

Hi to all,
i've big problem with dinamic link to the x86 dll for leptonica.
The example process starts with :

using (var engine = new TesseractEngine(@"./tessdata", "eng", EngineMode.Default))

But i receive immediately an exception due to a null value received from this process (module LibraryLoader inside InteropDotNet):

                IntPtr dllHandle = CheckCustomSearchPath(fileName, platformName);
                if (dllHandle == IntPtr.Zero)
                    dllHandle = CheckExecutingAssemblyDomain(fileName, platformName);
                if (dllHandle == IntPtr.Zero)
                    dllHandle = CheckCurrentAppDomain(fileName, platformName);
                if (dllHandle == IntPtr.Zero)
                    dllHandle = CheckCurrentAppDomainBin(fileName, platformName);
                if (dllHandle == IntPtr.Zero)
                    dllHandle = CheckWorkingDirecotry(fileName, platformName);

                if (dllHandle != IntPtr.Zero)
                    loadedAssemblies[fileName] = dllHandle;
                else
                    throw new DllNotFoundException(string.Format("Failed to find library \"{0}\" for platform {1}.", fileName, platformName));

One more thing is that in the module UnixLibraryLoaderLogic inside InteropDotNet the below code check the operating system type, and choose the File extension for the leptonica libraries...the strange thing is that there isn't a file in the project with extension .dylib or .os, but only .dll

private static readonly string FileExtension = SystemManager.GetOperatingSystem() == OperatingSystem.MacOSX ? ".dylib" : ".so";

other thing is that this code add the constant "lib" before the name of the libraries:

            if (!fileName.StartsWith("lib", StringComparison.OrdinalIgnoreCase))
               fileName = "lib" + fileName;

So, the final name to search of the leptonica libraries,will be : libleptonica.1.8.20.os, that does't exist.

Thank in advance for the help.

[charlesw]

Sorry not going to be much use with the Linux support. Recommend you have a look on the issue tracker on how to set this up. You will need to provide the library the nuget package only includes windows version as you noticed.

…

On Mon, 13 Feb 2023, 22:01 Genko71, ***@***.***> wrote: Hi to all, i've big problem with dinamic link to the x86 dll for leptonica. The example process starts with : using (var engine = new TesseractEngine(@"./tessdata", "eng", EngineMode.Default)) But i receive immediately an exception due to a null value received from this process (module LibraryLoader inside InteropDotNet): IntPtr dllHandle = CheckCustomSearchPath(fileName, platformName); if (dllHandle == IntPtr.Zero) dllHandle = CheckExecutingAssemblyDomain(fileName, platformName); if (dllHandle == IntPtr.Zero) dllHandle = CheckCurrentAppDomain(fileName, platformName); if (dllHandle == IntPtr.Zero) dllHandle = CheckCurrentAppDomainBin(fileName, platformName); if (dllHandle == IntPtr.Zero) dllHandle = CheckWorkingDirecotry(fileName, platformName); if (dllHandle != IntPtr.Zero) loadedAssemblies[fileName] = dllHandle; else throw new DllNotFoundException(string.Format("Failed to find library \"{0}\" for platform {1}.", fileName, platformName)); One more thing is that in the module UnixLibraryLoaderLogic inside InteropDotNet the below code check the operating system type, and choose the File extension for the leptonica libraries...the strange thing is that there isn't a file in the project with extension .dylib or .os, but only .dll private static readonly string FileExtension = SystemManager.GetOperatingSystem() == OperatingSystem.MacOSX ? ".dylib" : ".so"; other thing is that this code add the constant "lib" before the name of the libraries: if (!fileName.StartsWith("lib", StringComparison.OrdinalIgnoreCase)) fileName = "lib" + fileName; So, the final name to search of the leptonica libraries,will be : libleptonica.1.8.20.os, that does't exist. Thank in advance for the help. — Reply to this email directly, view it on GitHub <#635>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAB7HSHRYWOTJYAGEJOC2NLWXIIAFANCNFSM6AAAAAAU2DRTCU> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[Genko71]

Hi Charlesw,
i'm not on Unix system, i'm using Visual Studio 2019 on Windows 10 Pro 64 bit version 21H2.
I don't understand why the code go into the module UnixLibraryLoaderLogic inside InteropDotNet to get the leptonica library name to be dinamically loaded.

The problem is in this part of code:

    public static OperatingSystem GetOperatingSystem()
    {
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            return OperatingSystem.Windows;
        if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
            return OperatingSystem.Unix;
        if(RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
            return OperatingSystem.MacOSX;
        
        return OperatingSystem.Unknown;

for some reason, the code sees my system as Unix, when it is Windows instead.

Thank in advance.

[charlesw]

Oh sorry got confused 🙂

Well RuntimeInformation.IsOSPlatform is part of .net so that is odd indeed. Maybe try writing a small test program to see what the function is returning in an isolated context? I'm assuming you're also not using WSL or any VM etc?

[Genko71]

Hi Charles,
no, i'm not using WSL or VM, my system is a genuine windows system as show below:

I've build a small project, extracting a little part of your package source, i'm using the internal VS2019 android emulator.

This below identify the error regarding the wrong system intercept, as you can see the code set true to Unix System.

This regard the try to find the leptonica-1.82.0.dll by CheckExecutingAssemblyDomain, as you can see the file.exist function give me false

This by CheckWorkingDirecotry, it give me always false

This by CheckCurrentAppDomainBin
During this try the system give me an exception, due to the null value of AppDomain.CurrentDomain.BaseDirectory

Same situation for the try by CheckCurrentAppDomain

I don't know where to put the leptonica-1.82.0.dll, to permit tesseract to load it.

Thank in advance for the help.
Genko