Using OpenCV with Eclipse (plugin CDT) {#tutorial_linux_eclipse}
======================================
Prerequisites
-------------
Two ways, one by forming a project directly, and another by CMake Prerequisites
-# Having installed [Eclipse](http://www.eclipse.org/) in your workstation (only the CDT plugin for
C/C++ is needed). You can follow the following steps:
- Go to the Eclipse site
- Download [Eclipse IDE for C/C++
Developers](http://www.eclipse.org/downloads/packages/eclipse-ide-cc-developers/heliossr2) .
Choose the link according to your workstation.
-# Having installed OpenCV. If not yet, go @ref tutorial_linux_install "here".
Making a project
----------------
-# Start Eclipse. Just run the executable that comes in the folder.
-# Go to **File -\> New -\> C/C++ Project**
-# Choose a name for your project (i.e. DisplayImage). An **Empty Project** should be okay for this
example.
-# Leave everything else by default. Press **Finish**.
-# Your project (in this case DisplayImage) should appear in the **Project Navigator** (usually at
the left side of your window).
-# Now, let's add a source file using OpenCV:
- Right click on **DisplayImage** (in the Navigator). **New -\> Folder** .
- Name your folder **src** and then hit **Finish**
- Right click on your newly created **src** folder. Choose **New source file**:
- Call it **DisplayImage.cpp**. Hit **Finish**
-# So, now you have a project with a empty .cpp file. Let's fill it with some sample code (in other
words, copy and paste the snippet below):
@code{.cpp}
#include <opencv2/opencv.hpp>
using namespace cv;
int main( int argc, char** argv )
{
Mat image;
image = imread( argv[1], 1 );
if( argc != 2 || !image.data )
{
printf( "No image data \n" );
return -1;
}
namedWindow( "Display Image", WINDOW_AUTOSIZE );
imshow( "Display Image", image );
waitKey(0);
return 0;
}
@endcode
-# We are only missing one final step: To tell OpenCV where the OpenCV headers and libraries are.
For this, do the following:
- Go to **Project--\>Properties**
- In **C/C++ Build**, click on **Settings**. At the right, choose the **Tool Settings** Tab.
Here we will enter the headers and libraries info:
-# In **GCC C++ Compiler**, go to **Includes**. In **Include paths(-l)** you should
include the path of the folder where opencv was installed. In our example, this is
/usr/local/include/opencv.
@note If you do not know where your opencv files are, open the **Terminal** and type:
@code{.bash}
pkg-config --cflags opencv
@endcode
For instance, that command gave me this output:
@code{.bash}
-I/usr/local/include/opencv -I/usr/local/include
@endcode
-# Now go to **GCC C++ Linker**,there you have to fill two spaces:
First in **Library search path (-L)** you have to write the path to where the opencv libraries
reside, in my case the path is: :
/usr/local/lib
Then in **Libraries(-l)** add the OpenCV libraries that you may need. Usually just the 3 first
on the list below are enough (for simple applications) . In my case, I am putting all of them
since I plan to use the whole bunch:
opencv_core opencv_imgproc opencv_highgui opencv_ml opencv_video opencv_features2d
opencv_calib3d opencv_objdetect opencv_contrib opencv_legacy opencv_flann
If you don't know where your libraries are (or you are just psychotic and want to make sure
the path is fine), type in **Terminal**:
@code{.bash}
pkg-config --libs opencv
@endcode
My output (in case you want to check) was:
@code{.bash}
-L/usr/local/lib -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann
@endcode
Now you are done. Click **OK**
- Your project should be ready to be built. For this, go to **Project-\>Build all**
In the Console you should get something like
If you check in your folder, there should be an executable there.
Running the executable
----------------------
So, now we have an executable ready to run. If we were to use the Terminal, we would probably do
something like:
@code{.bash}
cd <DisplayImage_directory>
cd src
./DisplayImage ../images/HappyLittleFish.png
@endcode
Assuming that the image to use as the argument would be located in
\<DisplayImage_directory\>/images/HappyLittleFish.png. We can still do this, but let's do it from
Eclipse:
-# Go to **Run-\>Run Configurations**
-# Under C/C++ Application you will see the name of your executable + Debug (if not, click over
C/C++ Application a couple of times). Select the name (in this case **DisplayImage Debug**).
-# Now, in the right side of the window, choose the **Arguments** Tab. Write the path of the image
file we want to open (path relative to the workspace/DisplayImage folder). Let's use
**HappyLittleFish.png**:
-# Click on the **Apply** button and then in Run. An OpenCV window should pop up with the fish
image (or whatever you used).
-# Congratulations! You are ready to have fun with OpenCV using Eclipse.
### V2: Using CMake+OpenCV with Eclipse (plugin CDT)
Say you have or create a new file, *helloworld.cpp* in a directory called *foo*:
@code{.cpp}
#include <opencv2/opencv.hpp>
using namespace cv;
int main ( int argc, char **argv )
{
Mat img(480, 640, CV_8U);
putText(img, "Hello World!", Point( 200, 400 ), FONT_HERSHEY_SIMPLEX | FONT_ITALIC, 1.0, Scalar( 255, 255, 0 ));
imshow("My Window", img);
waitKey();
return 0;
}
@endcode
-# Create a build directory, say, under *foo*: mkdir /build. Then cd build.
-# Put a `CmakeLists.txt` file in build:
@code{.bash}
PROJECT( helloworld_proj )
FIND_PACKAGE( OpenCV REQUIRED )
ADD_EXECUTABLE( helloworld helloworld.cxx )
TARGET_LINK_LIBRARIES( helloworld \f${OpenCV_LIBS} )
@endcode
-# Run: cmake-gui .. and make sure you fill in where opencv was built.
-# Then click configure and then generate. If it's OK, **quit cmake-gui**
-# Run `make -j4` (the -j4 is optional, it just tells the compiler to build in 4 threads). Make
sure it builds.
-# Start eclipse. Put the workspace in some directory but **not** in foo or `foo\build`
-# Right click in the Project Explorer section. Select Import And then open the C/C++ filter.
Choose *Existing Code* as a Makefile Project.
-# Name your project, say *helloworld*. Browse to the Existing Code location `foo\build` (where
you ran your cmake-gui from). Select *Linux GCC* in the *"Toolchain for Indexer Settings"* and
press *Finish*.
-# Right click in the Project Explorer section. Select Properties. Under C/C++ Build, set the
*build directory:* from something like `${workspace_loc:/helloworld}` to
`${workspace_loc:/helloworld}/build` since that's where you are building to.
-# You can also optionally modify the Build command: from make to something like
`make VERBOSE=1 -j4` which tells the compiler to produce detailed symbol files for debugging and
also to compile in 4 parallel threads.
-# Done!