Summary

• Installed from here 64bit version https://github.com/UB-Mannheim/tesseract/wiki
• installed libleponica with cygwin64 (and I can locate all the files, I just dont know where go is searching for the include folder?)
• and run the example:

package main

import (
	"fmt"

	"github.com/otiai10/gosseract/v2"
)

func main() {
	client := gosseract.NewClient()
	defer client.Close()
	client.SetImage("screens\\tab\\1_1920x1080_20230324121444.png")
	text, _ := client.Text()
	fmt.Println(text)
	// Hello, World!
}

• and got this error:

# github.com/otiai10/gosseract/v2
tessbridge.cpp:5:10: fatal error: leptonica/allheaders.h: No such file or directory
    5 | #include <leptonica/allheaders.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

Things I tried:

• Add the include folder to the path
• installed the libs from cygwin

Environment

Windows 10

set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\User\AppData\Local\go-build
set GOENV=C:\Users\User\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\User\go\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\User\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=D:\Programme\Go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=D:\Programme\Go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.20.2
set GCCGO=gccgo
set GOAMD64=v1
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=D:\Git\ow-screenshot\go.mod
set GOWORK=
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=C:\Users\User\AppData\Local\Temp\go-build2662576145=/tmp/go-build -gno-record-gcc-switches

go version go1.20.2 windows/amd64

tesseract v5.3.0.20221222
 leptonica-1.78.0
  libgif 5.1.4 : libjpeg 8d (libjpeg-turbo 1.5.3) : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11 : libwebp 0.6.1 : libopenjp2 2.3.0
 Found AVX2
 Found AVX
 Found FMA
 Found SSE4.1
 Found libarchive 3.5.0 zlib/1.2.11 liblzma/5.2.3 bz2lib/1.0.6 liblz4/1.7.5 libzstd/1.4.5
 Found libcurl/7.77.0-DEV Schannel zlib/1.2.11 zstd/1.4.5 libidn2/2.0.4 nghttp2/1.31.0

I saw those issues but never found a fix: #271 #234 #263 #260

After I set this: go env -w CGO_CXXFLAGS="-O2 -g -ID:\Programme\cygwin64\usr\include" (If somebody is maybe confused whats in the include folder:)

My error was a different one:

# command-line-arguments
D:\Programme\Go\pkg\tool\windows_amd64\link.exe: running g++ failed: exit status 1
D:/Programme/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -llept
D:/Programme/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -ltesseract
D:/Programme/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -llept
D:/Programme/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/10.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -ltesseract
collect2.exe: error: ld returned 1 exit status

I spent a lot of time solving this problem. I'm on the Windows platform, but I think it should be similar for other platforms.

First, I installed MSYS2 and used it to install the MinGW toolchain. Then, I installed Leptonica using pacman. As for Tesseract, I compiled and installed it from source code. Once I made sure both packages were installed correctly, I used the following command:

pkg-config --cflags --libs lept tesseract

If it shows: -IC:/msys64/mingw64/include/leptonica -IC:/msys64/mingw64/include -LC:/msys64/mingw64/lib -lleptonica -ltesseract -larchive -lcurl then everything is fine.

After that, I made modifications to otiai10's code in client.go:

/* #cgo pkg-config: lept tesseract #cgo CXXFLAGS: -std=c++0x #cgo CPPFLAGS: -Wno-unused-result #include <stdlib.h> #include <stdbool.h> #include "tessbridge.h" */ import "C"

That solved the problem.

By the way, you also need to set an environment variable TESSDATA_PREFIX to let Tesseract know where your training data is stored. For example, mine is set to: C:\msys64\usr\local\share\tessdata.

I bumped into this same issue on MacOS Ventura 13.5. It seems like that with the latest library versions installed by Homebrew ([email protected], [email protected]), one of two things need to happen in order to get this library to work.

1. Edit this line to read -lleptonica and then set the environment variables as suggested in #234
2. Use the pkg-config suggestion above.

The latter doesn't require any environment variables, so it seems a much more portable way to get up and running. I don't fully understand the ramifications of using pkg-config, though. If it doesn't introduce backward incompatibility, would you be open to using it?