Using cmake-gui to Create MinGW lib for OpenCV 2.4.13

Recently, I have tried to learn how to use OpenCV. Of course, the first thing is to install OpenCV. The version I tried to install is 2.4.13. The development tools I used is MinGW g++. After download and install all the tools (including cmake), I soon found out that there is no library for MinGW g++ in the distribution. This means I need to build my own if I want to use g++. The search is on…

There is not much information I can find for my environment which is Windows 10 and using g++ as my main c++ compiler. After putting the pieces together, I eventually hit the right path, the following is my procedure for building the MinGW lib for OpenCV 2.4.13:

  1. run cmake-gui as follows:
    cmake-gui -G "MinGW Makefiles"

    Setup the location for source (in my case is D:/WinApps/opencv/sources) and the binaries (D:/WinApps/opencv/build/x86/mingw). Add the following two entries as well:

    CMAKE_CXX_COMPILER <em>path_to_g++</em>
    CMAKE_C_COMPILER <em>path_to_gcc</em>
  2. Click Configure then with the default selection of components click Generate
  3. In cmd, change directory to D:/WinApps/opencv/build/x86/mingw and execute the command
    make all

    I encountered two errors during the make process:

    • A compile error for the file window_w32.cpp where the symbols ‘BTNS_AUTOSIZE‘ and ‘BTNS_BUTTON‘ were not declared. I fixed it by change them to 16 and 0 (where I found in one of the header file of g++).
    • Another error from the files in ‘nonfree’ module, for which I just deselect the ‘BUILD_opencv_nonfree’ from cmake and reclick Generate again, then make all again. This time, it went all the way to finish without serious error.
  4. Done!

I test drive the system by creating a c++ program loadimg.cpp which I copied from here.

g++ -I"D:\WinApps\opencv\build\include" -L"D:\WinApps\opencv\build\x86\mingw\lib" loadimg.cpp -lopencv_core2413 -lopencv_highgui2413 -o loadimg

The program compiled and run!

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