Convert heif to jpeg/png

About project：

based on nokiatech/heif: https://github.com/nokiatech/heif
Inspired by @yohhoy https://github.com/yohhoy/heic2hevc

When I had really pulled my hair out that I didn't know how to deal with iPhone heic file,the following library helped me.
https://github.com/monostream/tifig
I use the code in my project.

This project is in developing, and it needs some tweak.

Knowledge about HEIF format(written in Chinese): HEIF格式详细解读

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Part Ⅰ: Dependencies

1. glib2.0-dev

Since libvips has to have glib2.0-dev, you must make sure that you have installed it. If you had done it, you could circumvent the step.

How to installglib2.0-dev ?

ubuntu：

sudo apt-get install libglib2.0-dev

MSYS：

pacman -S glib2-devel
pacman -S glib2 2.48.2-1

2. libvips

libvips is a 2D image processing library. I use the library for generating JPEG and PNG, including cropping tiles of iPhone heic file. https://github.com/jcupitt/libvips

2.1 Download Link

https://github.com/jcupitt/libvips/releases
Recommended version: vips 8.6.3

2.2 Building libvips

To aviod using many dependencies, you'd better configure with the following arguments.

./configure --enable-debug=[yes] --enable-static --without-gsf  \
--without-fftw --without-magick --without-orc --without-lcms  --without-OpenEXR \
--without-poppler --without-rsvg  --without-zlib --without-openslide --without-matio \
--without-ppm  --without-analyze  --without-radiance  --without-cfitsio --without-libwebp\
 --without-pangoft2 --without-tiff --without-giflib --without-libexif

Check the summary at the end of configure carefully!
Check the summary at the end of configure carefully!!
Check the summary at the end of configure carefully!!!

When ending of configure, checking and make sure:

file import/export with libpng: 	yes (pkg-config libpng >= 1.2.9)
file import/export with libjpeg:	yes (pkg-config)

Error handle 1: lack of Expat library
If you don't meet the problem, please skip.

checking for XML_ParserCreate in -lexpat... no
configure: error: Could not find the

Error Source:libvips must have libexpat1-dev. So:

sudo apt install libexpat1-dev   // Ubuntu

Error handle 2: lack of libpng,libjpeg

file import/export with libpng: 	no
file import/export with libjpeg:	no   // or find by search

If you meet the problem, you must install them. For Ubuntu:

sudo apt install libpng16-dev   
sudo apt install libjpeg-dev

Continue

Once configure is looking OK, compile and install with the usual: By default this will install files to /usr/local.

make
sudo make install  

3. FFmpeg

ffmpeg: https://www.ffmpeg.org/
FFmpeg library support encoding and decoding of HEVC(H.254).
Check：

• libavcodec >=3.1
• libswscale >=3.1

Install or update FFmpeg library：
Ubuntu

sudo apt install libavcodec-dev
sudo apt install libswscale-dev

Msys + mingw64

pacman -S mingw-w64-x86_64-ffmpeg

If you can't install FFmpeg with the above method, you should build FFmpeg source code.

FFmpeg Download Link：https://www.ffmpeg.org/download.html#releases
Recommand Version：FFmpeg 3.4.2 "Cantor"

Part Ⅱ: Build

1. At first, build Nokia heif library.

cd heif/build         
cmake ../srcs
cmake --build .

2. Waiting a few minutes,then

cd ..
cd ..
ls     // CMakeLists.txt  heif  heif2jpeg.cpp  READNE.md
mkdir build && cd build
cmake ..
cmake --build .

Check executable file(/build).

Error handle 1: can't find glib-object.h or glibconfig.h
The cause of the error is compiler don't have find the header file('glib2.0').
Check file: /srcs/example/CmakeList.txt

INCLUDE_DIRECTORIES(right path)  # glib-object.h

Example(ubuntu 16.04)：

INCLUDE_DIRECTORIES(/usr/include/glib-2.0)  # glib-object.h

Error handle 2: undefined reference
I think you may not follow the guide build step by step, so that some additional dependencies are needed. Re-build or add those dependencies by yourself.

Part Ⅲ: Usages

When compiler success,there is a executable file heic2jpg in /build/.

./heic2jpg inputFileName.heic outputFileName.jpeg

If you want to support more picture format, please change libvips configure arguments.

Error handle: libvips-cpp.so.42

./heic2jpeg: error while loading shared libraries: libvips-cpp.so.42:
cannot open shared object file: No such file or directory

update your ldconfig cache with this command:

sudo ldconfig

Suggestions for improvements are highly welcome!