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libjpeg-turbo for Android

This repository provides a working Android.mk build configuration for libjpeg-turbo, which means that you'll be able to build your app with ndk-build instead of resorting to toolchain trickery. Just add this repository as a Git submodule and you should be good to go.

Note however that this repository was originally created for a single purpose; to encode JPG files in a different NDK project. Therefore JNI bindings are not provided but a pull request is welcome. Also, any libjpeg-turbo feature that requires another dependency is currently not supported (incl. colorspace conversions). Again, pull requests are welcome.

Currrently, the following ABIs are supported:

armeabi
armeabi-v7a
armeabi-v7a-hard
arm64-v8a
x86
x86_64, requires Android NDK Revision 10e (May 2015) or later

SIMD/ASM optimizations are enabled for supported ABIs where possible. libjpeg-turbo does not support MIPS properly (yet). Since MIPS is not supported, you'll need to specify your supported ABIs in Application.mk instead of simply giving it APP_ABI := all.

Note that compiler optimization options are NOT included right now. If, for example, you wish to use -Ofast or other options, you'll need to add them yourself, possibly to your Application.mk.

Requirements

The following combinations are known to work:

Android NDK, Revision 10e (May 2015)

Usage

First, set up a vendor folder in your own project. You can skip this step if you've already decided where you wish to put the module.

mkdir -p jni/vendor
echo 'include $(call all-subdir-makefiles)' >> jni/vendor/Android.mk

Then add this repo as a submodule to your own project.

git submodule add --name libjpeg-turbo \
  https://github.com/openstf/android-libjpeg-turbo.git jni/vendor/libjpeg-turbo

You should now be able to do LOCAL_STATIC_LIBRARIES += libjpeg-turbo in your own module, #include <turbojpeg.h> and ndk-build.

Updating libjpeg-turbo

You need to go and fetch libjpeg-turbo first. Download and extract the source package to jni/vendor/libjpeg-turbo. It's not a submodule because they still use SVN. Check jni/vendor/libjpeg-turbo/Android.mk to see which version of libjpeg-turbo is expected.

cd jni/vendor/libjpeg-turbo
cp ~/Downloads/libjpeg-turbo-1.4.1.tar.gz .
tar xzvf libjpeg-turbo-1.4.1.tar.gz

To make updating easier, the jni/vendor/libjpeg-turbo/libjpeg-turbo-*-*-* folder should contain only unmodified original source files. Do not configure or move files around, it will be a pain later. Just unpack the source package and leave it be as-is.

You may sometimes also need to update the convenience files in jni/vendor/libjpeg-turbo/include. This doesn't seem to happen very often, though.

Now update the SOURCE_PATH in jni/vendor/libjpeg-turbo/Android.mk. Then run ndk-build to make sure nothing broke.

Then git rm -r the previous libjpeg-turbo source and commit the new source with your Android.mk modification(s).

Contributing

See CONTRIBUTING.md.

License

See LICENSE. libjpeg-turbo itself is governed by its own license.