gosseract

To use gosseract on macOS, install the Tesseract dependency via Homebrew and then fetch the Go package.

brew install tesseract
go get -t github.com/otiai10/gosseract/v2

Because vcpkg builds Tesseract with MSVC, it provides .dll and .lib files. However, Go's CGO on Windows requires MinGW .a import libraries. You can generate these using gendef and dlltool (included with MinGW) by following these steps:

1. Generate a .def file from the Tesseract DLL.
2. Create the .a import library using the .def file.

Note: Replace tesseract55 with the specific version number of your installed DLL.

# Generate .def file from DLL
gendef tesseract55.dll

# Create MinGW import library
dlltool -d tesseract55.def -l libtesseract55.a -D tesseract55.dll

To use gosseract on Debian or Ubuntu, install the required Tesseract and Leptonica development libraries, then fetch the Go package.

sudo apt-get install -y libtesseract-dev libleptonica-dev tesseract-ocr-eng
go get -t github.com/otiai10/gosseract/v2

The error exit status 0xc0000135 indicates STATUS_DLL_NOT_FOUND. The binary compiled successfully, but the required Tesseract/Leptonica DLLs are not in the system path at runtime.

Solution: Add the directory containing your Tesseract DLLs (e.g., the vcpkg bin directory) to your PATH before running tests.

export PATH="/c/vcpkg/installed/x64-windows/bin:$PATH"

Tesseract cannot locate its language data files. You must download the required .traineddata files and set the TESSDATA_PREFIX environment variable to the directory containing them.

Steps:

1. Download the language data (e.g., English):

   curl -L -o /c/tessdata/eng.traineddata https://github.com/tesseract-ocr/tessdata/raw/main/eng.traineddata

2. Set the TESSDATA_PREFIX environment variable to that directory.

export TESSDATA_PREFIX=C:/tessdata

If you encounter undefined errors for core functions like Version or NewClient, CGO is likely disabled or failing. This causes Go to skip files containing import "C".

Solutions:

1. Ensure CGO_ENABLED=1 is set.
2. Verify GCC is installed and present in your PATH.
3. Ensure the CC environment variable points to a valid compiler.

Debug commands:

go env CGO_ENABLED  # Should be 1
go env CC           # Should show the path to gcc

This error occurs because a glob pattern like libtesseract*.a matches the symlink itself during creation.

Solution: Use a more specific glob pattern to target the actual library files instead of the symlink.

for f in libtesseract[0-9]*.a; do
  ln -sf "$f" libtesseract.a
done

This error occurs when the linker cannot find the Tesseract library.

Solutions:

1. Verify that import libraries (e.g., libtesseract.a) exist in your library directory.
2. Ensure CGO_LDFLAGS includes the correct library path.
3. Verify that preprocessflags_windows.go contains the correct LDFLAGS.

export CGO_LDFLAGS="-LC:/vcpkg/installed/x64-windows/lib"

This error indicates the MinGW import library is missing or incorrectly named. You may need to manually create the import library from the DLL.

Steps:

1. Generate a definition file and create the .a library from the DLL:

   cd /c/vcpkg/installed/x64-windows/bin
   gendef tesseract55.dll
   dlltool -d tesseract55.def -l libtesseract55.a -D tesseract55.dll
   mv libtesseract55.a ../lib/

2. Create a symlink with the standard name libtesseract.a in the library directory.

cd /c/vcpkg/installed/x64-windows/lib
ln -sf libtesseract55.a libtesseract.a

If Go cannot find the GCC compiler (even if it works in a bash shell), you must explicitly set the CC environment variable to the full path of the executable.

Solution: Set CC to the absolute path of your gcc.exe.

export CC=C:/mingw64/bin/gcc.exe