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Jean-Michel Gonet edited this page Jan 13, 2019 · 35 revisions

To write this part, my initial intention after installing a fresh Ubuntu distribution was to set up any well known IDE and click around until I could compile, debug and run the project. Boy, was I not naive! Several days later, I have had discarded Clion because it is a paying application, I had unsuccessfully tried Code::Blocks, Eclipse, and lost my patience before trying Qt Builder -- yet, I have not been able to find an acceptable IDE to just do the basic stuff with reasonable simplicity. And then I found this Stack Oveflow question «C++ IDE for Linux?» where accepted and most voted answer states that «UNIX is an IDE. All of it».

C++ - Linux is an IDE

Let's accept that in Linux we are not going to get a fancy IDE and content ourselves with a text editor. Two popular choices are:

The tool to debug code is gdb. It seems bleak, but you can actually do quite a job with it. Have a look on those videos:

In the first step, a little bit below, I will give short specific instructions for compiling with debug symbols, and debug the programs with gdb.

apt-get

This is the official package manager of most Linux distribution. Most popular applications are distributed through it and it is most usually pre-installed.

pkg-config

In a linux distribution, there is the highest chance that pkg-config is already installed. Anyway, you can give it a try; should it be already installed it will just tell you:

sudo apt-get update
sudo apt-get install pkg-config

CMake

You will need it to compile OpenCV, so you better install it now:

sudo apt-get install cmake

OpenCV

As a prerequisite, you need to have the following libraries from apt-get:

# required:
sudo apt-get install \
   libgtk-3-dev \
   pkg-config \
   libavcodec-dev \
   libavformat-dev \
   libswscale-dev 
# Optional:
sudo apt-get install \
   python-dev \
   python-numpy \
   libjpeg-dev \
   libpng-dev \
   libtiff-dev \
   libjasper-dev \
   libdc1394-22-dev

Once you've installed all prerequisites, fetch the sources of the latest release of OpenCV from the official repository at github, and unzip it:

wget https://github.com/opencv/opencv/archive/4.0.1.zip
unzip 4.0.1.zip

Prepare and compile:

cd opencv-4.0.1
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTS=OFF -DCMAKE_INSTALL_PREFIX=/usr/local ..
make -j2  # Number of processors. Don't use more that you computer has.

Go for a walk; this takes ages. If process breaks, you can launch again by just retyping:

make -j2

When compilation is done, complete the installation:

sudo make install
sudo ldconfig

To check if the library is available as a dependency:

pkg-config --list-all | grep opencv
> opencv                         OpenCV - Open Source Computer Vision Library

You can now delete the sources folder; you don't need it any more:

cd ..
cd ..
rm -rf opencv-3.4.1
rm 3.4.1.zip

Gtkmm

Gtkmm is the Gtk for C++:

sudo apt-get install libgtkmm-3.0-dev

To check if the library is available as a dependency:

pkg-config --list-all | grep gtkmm
gtkmm-3.0                      gtkmm - C++ binding for the GTK+ toolkit

Git

To install Git:

sudo apt-get install git

And to verify that Git is present:

git --version
> git version 2.7.4

Launching application in Linux

Clone the example project, configure it with debug symbols, and build it:

cd go-to-your-working-folder
git clone https://github.com/cpp-tutorial/raspberry-cpp-gtk-opencv.git
cd raspberry-cpp-gtk-opencv
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Debug ../src
make

To debug with gdb, assuming that you're still in build folder:

gdb ./rascapp
[Now you're in gdb]
b main-window.cpp:10  # Place a break-point on line 10 of this file.
run                   # Run the program. It will stop at the break point.
where                 # It will show the stack trace
list                  # It will show some context.
print width           # Displays the value of this variable
n                     # Step over
s                     # Step into
c                     # To continue the program
q                     # Quit gdb

Configure Vim as an IDE

For example:

In the src folder, create a .vimrc file. This will be like a workspace configuration. In it, place:

set path+=src/**10
autocmd vimenter * NERDTreeVCS

To open include file:

  • gf : Open it.
  • C-W f : Open it in a separate tab.
  • C-W v : Open current file in a vertical split. Then you can gf to jump to the include file.

To go back after opening an include file:

  • gf : Open an include file.
  • Ctrl + O : Brings you back to the previous file.
  • Ctrl + I : If you're back from a file, then jumps into the next file.
  • The mnemonic would be O = OUT, I = IN => Ctrl - O brings you out, Ctrl brings you in. If every jump is like going through a door, that is. (comment by kronn in https://stackoverflow.com/questions/133626/how-do-you-return-from-gf-in-vim)

Create a symlink from the src folder to the compile_commands.json:

ln -s build/compile_commands.json compile_commands.json

To set up formatting:

set path+=src/**10              " For 'gf', looks in current folder, and up to 10 level of sub-sub-folders
set hidden                      " For 'gf', let's you go to next file without requiring to save current.                 
set cindent shiftwidth=4        " In C/C++, size of the tabulation increase each time you have a {
set tabstop=4                   " In all files, size of the Tab
set expandtab                   " Use spaces instead of Tab
autocmd vimenter * NERDTreeVCS  " Automatically opens NERDTree

To compile and run using vim and conque:

troubleshooting

No core dumps

This was driving me nuts. Like the poor Davidea explains in his post, https://stackoverflow.com/questions/13122480/core-dump-apport-no-crash-report, there was something wrong in my application that produced a segmentation fault, the core was allegedly dumped, but nowhere to be found.

See here about configuring core dumping:

Verify that user limits for core:

ulimit -c
> 0
ulimit -c unlimited
ulimit -c
> unlimited

Segmentation fault while compiling.

If you get an error like the following:

[ 95%] Building CXX object modules/stitching/CMakeFiles/opencv_perf_stitching.dir/perf/opencl/perf_stitch.cpp.o

c++: internal compiler error: Segmentation fault (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-7/README.Bugs> for instructions.
modules/stitching/CMakeFiles/opencv_perf_stitching.dir/build.make:62: recipe for target 'modules/stitching/CMakeFiles/opencv_perf_stitching.dir/perf/opencl/perf_stitch.cpp.o' failed
make[2]: *** [modules/stitching/CMakeFiles/opencv_perf_stitching.dir/perf/opencl/perf_stitch.cpp.o] Error 4
CMakeFiles/Makefile2:4438: recipe for target 'modules/stitching/CMakeFiles/opencv_perf_stitching.dir/all' failed
make[1]: *** [modules/stitching/CMakeFiles/opencv_perf_stitching.dir/all] Error 2
Makefile:162: recipe for target 'all' failed
make: *** [all] Error 2

This is usually a problem with not having enough memory. If, like me, you're using a virtual Linux machine, then the solution is simply increasing the available memory. If not, then try not having multi-threaded compilation (don't use make -j option).

Se more about this issue: https://github.com/opencv/opencv/issues/8552

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