I downloaded Tesseract OCR for Android from here and I’m trying to build it as a library project for my own app using the NDK. I’ve received some useful feedback on how to do this here. First, I do this on the command-line ([path] is shorthand for the path to the tess-two project):
> cd [path]\tess-two
> C:\android-ndk-r8b-windows\android-ndk-r8b\ndk-build -j8
"Compile thumb : lept <= adaptmap.c
[...]
"Compile++ thumb : lept <= writefile.cpp
Prebuilt : libgnustl_static.a <= <NDK>/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi/
"Compile++ thumb : tess <= applybox.cpp
[...]
"Compile++ thumb : tess <= tessbaseapi.cpp
"Compile thumb : lept <= adaptmap.c
[...]
"Compile++ thumb : lept <= pixa.cpp
Prebuilt : libgnustl_static.a <= <NDK>/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi-v7a/
"Compile++ thumb : lept <= jni.cpp
[...]
"Compile++ thumb : tess <= tessbaseapi.cpp
"Compile x86 : lept <= affine.c
[...]
"Compile++ x86 : lept <= readfile.cpp
Prebuilt : libgnustl_static.a <= <NDK>/sources/cxx-stl/gnu-libstdc++/4.6/libs/x86/
"Compile++ x86 : tess <= baseapi.cpp
[...]
"Compile++ x86 : tess <= wordclass.cpp
SharedLibrary : liblept.so
SharedLibrary : liblept.so
"Compile++ x86 : tess <= tessbaseapi.cpp
SharedLibrary : liblept.so
"Compile++ x86 : tess <= wordrec.cpp
SharedLibrary : libtess.so
Install : liblept.so => libs/x86/liblept.so
Install : liblept.so => libs/armeabi/liblept.so
SharedLibrary : libtess.so
Install : liblept.so => libs/armeabi-v7a/liblept.so
SharedLibrary : libtess.so
Install : libtess.so => libs/armeabi/libtess.so
Install : libtess.so => libs/armeabi-v7a/libtess.so
Install : libtess.so => libs/x86/libtess.so
> C:\Users\User\android-sdk\tools\android.bat update project --path .
Failed to convert path to a short DOS path: C:\Windows\system32\java.exe
'javaw_exe' is not recognized as an internal or external command,
operable program or batch file.
Updated local.properties
Updated file [path]\tess-two\proguard-project.txt
It seems that there are sub-projects. If you want to update them
please use the --subprojects parameter.
> set JAVA_HOME=C:\Java\JDK
> Buildfile: [path]\tess-two\build.xml
-set-mode-check:
-set-release-mode:
-release-obfuscation-check:
[echo] proguard.config is ${proguard.config}
-check-env:
[checkenv] Android SDK Tools Revision 20.0.3
[checkenv] Installed at C:\Users\User\android-sdks
-setup:
[echo] Project Name: tess-two
[gettype] Project Type: Android Library
-build-setup:
[echo] Resolving Build Target for tess-two...
[gettarget] Project Target: Google APIs
[gettarget] Vendor: Google Inc.
[gettarget] Platform Version: 4.1
[gettarget] API level: 16
[echo] ----------
[echo] Creating output directories if needed...
[echo] ----------
[echo] Resolving Dependencies for tess-two...
[dependency] Library dependencies:
[dependency] No Libraries
[dependency]
[dependency] ------------------
[dependency] API<=15: Adding annotations.jar to the classpath.
[echo] ----------
[echo] Building Libraries with 'release'...
[subant] No sub-builds to iterate on
-pre-build:
-code-gen:
[mergemanifest] Found Deleted Target File
[mergemanifest] Merging AndroidManifest files into one.
[mergemanifest] Manifest merger disabled. Using project manifest only.
[echo] Handling aidl files...
[aidl] No AIDL files to compile.
[echo] ----------
[echo] Handling RenderScript files...
[renderscript] No RenderScript files to compile.
[echo] ----------
[echo] Handling Resources...
[aapt] Found new input file
[aapt] Generating resource IDs...
[echo] ----------
[echo] Handling BuildConfig class...
[buildconfig] No need to generate new BuildConfig.
-pre-compile:
-compile:
[echo] Creating library output jar file...
-post-compile:
-obfuscate:
-dex:
[echo] Library project: do not convert bytecode...
-crunch:
[crunch] Crunching PNG Files in source dir: [path]\tess-two\res
[crunch] To destination dir: [path]\tess-two\bin\res
[crunch] Crunched 0 PNG files to update cache
-package-resources:
[echo] Library project: do not package resources...
-package:
[echo] Library project: do not package apk...
-post-package:
-release-prompt-for-password:
-release-nosign:
[echo]
[propertyfile] Updating property file: [path]\tess-two\bin\build.prop
[propertyfile] Updating property file: [path]\tess-two\bin\build.prop
[propertyfile] Updating property file: [path]\tess-two\bin\build.prop
[propertyfile] Updating property file: [path]\tess-two\bin\build.prop
-release-sign:
-post-build:
release:
BUILD SUCCESSFUL
Total time: 1 second
Then, I do this:
File -> Import -> Android -> Existing Code Into Workspace -> Browse -> Select current workspace directory -> Make sure tess-two is selected in the list that comes up -> Finish.
Then I right-click on my own app, go to Properties -> Android tab -> Add… (under Library section) -> select tess-two -> Click OK -> Check “Is Library” -> OK.
However, after all this, I still get the follwing error when running my app:
09-23 13:02:42.532: E/AndroidRuntime(675): Caused by: java.lang.UnsatisfiedLinkError: Couldn't load lept: findLibrary returned null
09-23 13:02:42.532: E/AndroidRuntime(675): at java.lang.Runtime.loadLibrary(Runtime.java:365)
09-23 13:02:42.532: E/AndroidRuntime(675): at java.lang.System.loadLibrary(System.java:535)
09-23 13:02:42.532: E/AndroidRuntime(675): at com.googlecode.tesseract.android.TessBaseAPI.<clinit>(TessBaseAPI.java:47)
The project.properties for my own app is:
target=android-16
android.library.reference.1=..\\OpenCV\\sdk\\java
android.library.reference.2=../Tesseract/tess-two
android.library=true
What’s going on?
I got it, the problem was that I wasn’t properly initializing the API in my code. The proper syntax is:
assuming you’ve got a folder “tessdata” under mnt/sdcard. Now it loads perfectly! Thanks so much for all your help, rmthesis!