Hi, I've been following an OpenCV tutorial from a book. Prior to it, I have OpenCV already installed on my machine. I'm working with OpenCV & C++ on a terminal and compile my program with CMake. Here's my Ubuntu & OpenCV version :
Ubuntu 18.04.4 LTS
OpenCV version : 4.2.0
In the book whenever they use imshow(), it shows a window with a toolbar and status bar on it, mine is not. And later on the next few chapters, they still use this toolbar for many purposes. After searching for a while, I found out that it is using Qt GUI. So, I went on to install Qt using these following codes :
sudo apt-get install qtcreator
sudo apt-get install qt5-default
And when I checked my Qt version, this is what I got :
$ qmake --version
QMake version 3.1
Using Qt version 5.9.5 in /usr/lib/x86_64-linux-gnu
So, now I have Qt installed in my machine, but how do I integrate this with my OpenCV so I can use it on my programs other than putting highgui lib ? I encountered this error :
The library is compiled without QT support in function
I've been looking around online but still don't know how. Do I need to entirely uninstall OpenCV and compile it again with QT using CMake ?
UPDATE
Apparently there was no other way beside completely uninstall OpenCV and then compile & reinstalling it with QT. This is what I do :
Uninstall OpenCV (already reinstalled 3 times)
sudo apt-get purge '*opencv*'
sudo find / -name "*opencv*" -exec rm -rf {} \;
Cloning OpenCV and OpenCV contrib from Github, and during building with CMake, put WITH_QT = ON. here's the full set up that I used :
cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/usr/local \
-D INSTALL_C_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D OPENCV_GENERATE_PKGCONFIG=ON \
-D WITH_TBB=ON \
-D WITH_V4L=ON \
-D WITH_QT=ON \
-D WITH_OPENGL=ON \
-D OPENCV_EXTRA_MODULES_PATH=~/opencv_build/opencv_contrib/modules \
-D BUILD_EXAMPLES=ON ..
But why does I still get this error on any project with QT on it (I have QT properties on my createButton function) even after I entirely reinstall, build and make OpenCV with WITH_QT=ON using WITH_QT=ON ? Did Does CMake failed to locate QT ?? Here's the full exeption :
terminate called after throwing an instance of 'cv::Exception' what():
OpenCV(4.2.0-dev) /home/raisa/opencv_build/opencv/modules/highgui/src/window.cpp:597:
error: (-213:The function/feature is not implemented)
The library is compiled without QT support in function
function 'createButton'
[2] 10467 abort (core dumped) ./exerc13
Here's the function createButton that causing error
//Create buttons
createButton("Blur", blurCallback, NULL, QT_CHECKBOX, 0);
createButton("Grey", greyCallback, NULL, QT_RADIOBOX, 0);
createButton("RGB", bgrCallback, NULL, QT_RADIOBOX, 1);
createButton("Sobel", sobelCallback, NULL, QT_PUSH_BUTTON, 0);
Literally just because I have QT properties there and it's causing error "The library is compiled without QT support". Any advice ?
UPDATE 2
I read about explicit path definition for Qt integration instead of just putting WITH_QT=ON. So I decided to go with cmake-gui and defined each path for Qt path configuration. Like this :
WITH_QT=ON (checked in cmake-gui)
Qt5Concurrent_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5Concurrent
Qt5Core_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5Core
Qt5Gui_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5Gui
Qt5OpenGL_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5OpenGL
Qt5Test_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5Test
Qt5Widgets_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5Widgets
Qt5_DIR = /home/raisa/Qt5.9.9/5.9.9/gcc_64/lib/cmake/Qt5
(Qt installation folowing installation docs from Qt Wiki)
Again, OpenCV was build & installed perfectly with CMake. Tested by running simple programs. But still encounter the same error for Qt. Any advice ? Thank you.
