I want to include Anaconda's Python 3.6 in my Qt C++ application. The reason why is that I want to be able to include a neural network in my C++ application, which is written in Python.
I tried to include Python in the following way, which I found online:
INCLUDEPATH += /home/[username]/anaconda3/include/python3.6m
LIBS += -L/home/[username]/anaconda3/lib/ -lpython3.6m
It finds the Python.h header but linking to the Python libraries causes Qt Creator to (apparently) use the Qt libraries of Anaconda and not the ones I downloaded and installed in my home folder.
This is problematic for two reasons:
My program needs Qt 5.9.1 and does not compile with Qt 5.6 (Anaconda's version)
Even if it compiled with Qt 5.6 there are suddenly errors of missing libraries, see below:
Is there any way to include Python from Anaconda but tell Qt Creator to use my custom Qt Version?
Unknowingly, I had the same problem again with a different application and thus posted a new question because I thought it was a different issue.
I found a solution in the mean time and posted the answer here.
I am working on a qt app which runs on am ios device. I am building the app on a Mac OSX laptop. It uses C++ for most part of it. I need to build the app with boost C++ library to use boost asio. So following are the steps I did:
1. Install boost on my mac laptop using port install boost. This puts boost headers into /opt/local/include & boost libs into /opt/local/lib as I see.
2.Next, I used the following lines in my qt app`s .pro file to build
INCLUDEPATH += /opt/local/include
LIBS += -L/opt/local/lib
LIBS += -lboost_system-mt -lboost_thread-mt
Then, I build it. It says "symbols not found for architecture arm64" & "linker command failed with exit code 1"
Can anyone please point out what is the correct way to build boost for a qt app running on ios ?
To use boost on iOS, you need a "cross-compiled" version, for the iPhone's processor architecture. The version you installed locally on your Mac was compiled for architecture x86_64. For an iOS app you need armv7 and arm64.
Fortunately, there seems to be a precompiled boost library for iOS available under https://github.com/danoli3/ofxiOSBoost, which looks like it's exactly what you need. Maybe you can have a look at that.
I've downloaded Qt 4.8.2 library, Qt Creator 2.5.2, and manually installed MingW with w32api version 3.13 and GCC/g++ version 4.7.0.1. My OS is Windows 7 Ultimate x64.
I can create a sample "Plain C++ project" in Qt Creator; compile and run that console application using g++ without any issue.
But I cannot run a Qt application. I used Qt Creator, created a dummy Qt Application using Creator's "Qt Gui Application" template. The project can be compiled successfully, without any error or warning. But the binary keeps crashing when I try to run (both from Qt Creator and Windows Explorer) it. Both debug and release builds crash. It crashes even before showing main window.
MingW is installed in C:\MingW and C:\MingW\bin is in PATH. Qt is installed in C:\Qt\4.8.2 and C:\Qt\4.8.2\bin is in PATH.
I analyzed generated exe of the Qt Gui Application output with Dependency Walker and found that it found all required DLLs:
c:\windows\system32\KERNEL32.DLL
c:\windows\system32\MSVCRT.DLL
c:\mingw\bin\LIBGCC_S_DW2-1.DLL
c:\mingw\bin\LIBSTDC++-6.DLL
c:\qt\4.8.2\bin\QTCORE4.DLL
c:\qt\4.8.2\bin\QTGUI4.DLL
So, what's causing the runtime crash?
EDIT
I also tried Qt's example projects: 2dpainting and addressbook - both crashed when they were launched.
You should build Qt with the MinGW compiler you're using to build your application. GCC is generally less sensitive to binary compatibility issues than MSVC is, but Qt is a big, complex framework library. If anything would expose those kinds of issues, Qt would probably be on the short list.
Building Qt is pretty straightforward, but it takes a lot of time and there always seems to be two or three patches I need to make to get things to build successfully.
The last time I built Qt (4.7.3) with MinGW, I had to make the following patches - I'm not sure whether they will still apply to Qt 4.8:
make sure not to enable C++11 mode in the compiler - there are several macros with concatenated string literals that break under the new C++11 extended literal syntax
there is a problem with how some distributions of MinGW incorporate the Microsoft extensions to float.h - I had to sometimes had to add the line:
#include_next <float.h>
to the end of the MinGW-specific float.h so the generic GCC float.h would get processed properly. I had to do this for nuwen 4.7.0 lib/gcc/i686-pc-mingw32/4.7.0/include/float.h and TDM 4.6.1 32-bit distro lib/gcc/mingw32/4.6.1/include/float.h (the 64-bit distro of TDM didn't need this patch).
patch qmake\Makefile.win32-g++ and qmake\Makefile.win32-g++-sh to remove the -static-libstdc++ option that GCC doesn't recognize (and now errors out on instead of ignores)
patch mkspecs/win32-g++/qmake.conf to move the -Wl, in the QMAKE_LFLAGS_EXCEPTIONS_ON macro to its proper place in QMAKE_FLAGS:
QMAKE_LFLAGS = -Wl,-enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc
QMAKE_LFLAGS_EXCEPTIONS_ON = -mthreads
copy make.exe to mingw32-make.exe in MinGW's bin directory if there's not already a mingw32-make.exe
Then building Qt consists of:
set QTDIR=<location of Qt source directory> # where configure.exe is
set PATH=%QTDIR%\bin;c:\MinGW\bin;%PATH%
set INCLUDE=
set LIB=
cd %QTDIR%
mingw32-make confclean # (this should fail the first time, since there's nothing to clean)
configure.exe -opensource -debug-and-release -nomake examples -nomake demos -nomake tests -platform win32-g++ # and accept the GPL license
mingw32-make
This takes a while... hopefully nothing else will need patching.
I also got this problem. I'm a Qt n00b and tought, when installing Qt-libraries, that "well I already have Mingw installed so I skip installing the Mingw that comes with Qt". That gave me prolems. When installing mingw that came with Qt everything worked ok.
So my advice to anyone googling to this question (like I did) is to instead of using your already installed Mingw, install the one with Qt and use that (otherwise you have to build the Qt libraries within your Mingw, like the answer from Michael Burr)
I would like to create a gui application with Qt, using opencv on Windows XP. I used both Qt and opencv before, but never together. Long story short, I'm unable to get opencv work with Qt.
As on all the forums I searched there are just little pieces of information scattered around, usually with no answer, I summarize here all the steps I've taken.
Downloaded the Qt SDK (4.6.3) for Windows, and used it for some time, successfully.
Downloaded the opencv 2.3.1 megapack for Windows, complete with binaries. I managed to compile my Qt project including opencv successfully, but any opencv function call resulted in a crash. I read on some forums that the binaries in the Windows megapack don't support Qt, and I have to build opencv myself
I downloaded the latest version of CMake (2.8).
I downloaded the source of opencv from here: http://code.opencv.org/svn/opencv/branches/2.3/
I downloaded the source for the version of Qt I had (4.6.3)
I found my old version of visual Studio 2005
I created a VS2005 project with CMake, checking the support for Qt. (WITH_QT checked)
I built opencv in VS2005. It created most of the libraries, but not all. Highgui was among the failed ones. The problem: Qt\4.6.3\src\corelib\global\qconfig.h was not found. There was no qconfig.h at all in the source I downloaded! I found some templates qconfig-large.h, qconfig-small.h etc., so I renamed one of them to qconfig.h. Now I got a screen full of linker errors.
I downloaded the latest Qt source instead (4.8.1). Now there is a source file qbenchmark.h that includes QtTest/qbenchmarkmetric.h which cannot be found.
I gave up, and tried MinGW.
I downloaded the latest MinGW (2011.11.18)
I set CMake to generate a MinGW makefile, but I got the following error:
.
CMake Error at C:/Program Files/CMake 2.8/share/cmake-2.8/Modules/Platform/Windows-g++.cmake:1 (INCLUDE):
include could not find load file:
C:/Program Files/CMake 2.8/share/cmake-2.8/Modules/Platform/Windows-gcc.cmake
Call Stack (most recent call first):
C:/Program Files/CMake 2.8/share/cmake-2.8/Modules/CMakeCXXInformation.cmake:59 (INCLUDE)
True, there is a Windows-g++.cmake file in the Modules/Platform directory, but it references Windows-gcc.cmake which does not exist!
Is there anyone who managed to build opencv with Qt support on Windows, and if yes, how?
Edit:
The problem is definitely with the Qt source. I managed to generate a MinGW makefile, and the build went all OK until it stopped in src/testlib/qtestsystem.h because there was an include for QtCore/qelapsedtimer.h which file is in a completely different directory! Does Qt release incomplete sources, or did I do something wrong?
Edit2
My torment continues. I cleaned everything and started anew. This time without even trying Visual Studio.
I downloaded the latest Qt libs with source (4.8.1)
I downloaded the latest MinGW (2011.11.18)
With CMake I successfully created a Makefile, and built it with MinGW. I got some shiny new libs (libopencv_core231, etv.). I was very happy, but how wrong I was to celebrate that soon!!
I downloaded the latest Qt SDK (strangely, it was 4.8.0, so I set Qt Creator to use the 4.8.1) and created a test program without opencv to see if it works. It worked!
I tried using opencv, just reading and displaying an image. It didn't work. exited with code -1073741511
I tried running the .exe directly, outside of Qt Creator. It complained of a missing libstdc++-6.dll
I did a search for it, and found on in my MinGW install (c:\mingw\bin, 958 KB), and one in my Qt install (c:\qt\mingw\bin, 793 KB) - this mingw came bundled with Qt.
I tried both, by copying them in the same folder where my .exe is, but neither worked. I got "The procedure entry point _ZNSt9exceptionD2Ev could not be located in the dynamic link library libstdc++-6.dll." with both. This was in debug, so I tried release, and I got a similar error, with some other entry point not found.
I searched the forums, and I found suggestions that I should link libstdc++ statically. I inserted -static-libgcc -static-libstdc++ at the lines QMAKE_LFLAGS = and QMAKE_LFLAGS_DEBUG = in the file c:\Qt\mkspecs\win32-g++\qmake.conf. This had no effect at all, even after restarting Qt Creator and rebuilding. If I don't copy the libstdc++-6.dll, it still requires it.
Of course, my simple test program without opencv runs from the exe without needing any libstdc++-6.dll, so that means my opencv build is responsible? I wanted to build opencv anew, but I cannot find any CMake settings referring to libstdc++ !
It might be a clue:
When using one of the libstdc++-6.dll files, the error about a missing entrypoint mentions QtGui4.dll. I have a debug build, so it should be QtGui*d*4.dll, shouldn't it? Are there different libstdc++s for debug and release? Either way, I tried to build release, but it didn't work either, same error
Is there no single person on this planet who tried using Qt with QtCreator and opencv 2.3 together on Windows xp, and succeeded? From searching all the forums and Qt archives, I could not find anyone. I'm ready to do the development in Linux, but I'll need a Windows release sooner or later anyway.
I'm trying to resist the temptation of the dark side, which whispers into my ears to forget Qt, MinGW, g++, opencv and try to hack together something in Visual Basic. Oh, the horrors!
Just FYI, I went basically through the same nightmare of combining Qt and OpenCV. This was my experience:
I downloaded the Qt SDK 4.7.4 with Qt Creator 2.4.1 and installed it, no problem.
I downloaded and installed OpenCV 2.4.2 and not knowing that it already came with MinGW...
I downloaded the MinGW compiler which of course had a different version than the one which came already with Qt
This completely messed up my CMake, even when I explicitly told CMake to use the Qt gcc.exe and g++.exe it also used some stuff from my freshly installed MinGW. Probably because I eagerly added every directory to my PATH variable. What a fool I was!
CMake was not able to generate any useful files, so I gave up and installed the OpenCV superpack, hoping this would make things easier.
6.I spent hours wondering, why Qt and OpenCV from the superpack didnt work properly together. I never quite understood. I had the same errors that other users describe here, like console programs crashing as soon as some OpenCV was included. The strange thing is, that I could start the executable manually from FileExplorer (I added all .dlls you could think of to the project folder: opencv_core242.dll, opencv_highgui242.dll, QtCore4.dll, QtGui4.dll and so on...) BUT I could not launch my little test program from within the Qt Creator environment.
I analysed if there was a problem with my DLLs using depends.exe and found out that even though I configured everything to be in DEBUG using the MinGW compiler, my program still tried to use QtCore4.dll and not QtCore4d.dll... So my best guess was, that it was mixing debug and release version.
I gave up using the superpack and again tried to use CMAKE first and then build OpenCV using the Qt MinGW version AND making sure to setup everything for Debug mode and enable the QT option. But no luck with that so far
I stopped using MinGW and switched over to MSVC2010, which works better. However I am still not able to debug the program since the MSVC2010 debugger engine seems to be missing. I dont really know how to manually add this but I am still working on it
So what I can definitely tell is that using Qt and OpenCV for somebody who has little experience is far from trivial!
You should build OpenCV from source, as you already did, it is no hassle. Note that recent versions of OpenCV can be built with and w/o Qt. Highgui optionally uses Qt! It is your choice if you build with or without Qt.
I used Qt libraries together with OpenCV for long time now. I never went for the SDK, instead I used the libs which are built for corresponding VS version. See here: http://qt.nokia.com/downloads/downloads#qt-lib
You can have it for VS2008 and VS2010, but earlier versions are also available built for VS2005. Old versions of Visual Studio suck so hard, why use them anyway.
Then I never had problems pulling it together in a CMake project. It goes along the lines of:
find_package(OpenCV)
find_package(Qt4 ${VOLE_MINIMUM_QT_VERSION} COMPONENTS QtCore QtGui)
find_package(Qt4 ${VOLE_MINIMUM_QT_VERSION} COMPONENTS QtOpenGL)
...
qt4_wrap_cpp(moc_sources ${vole_module_moc_sources})
qt4_wrap_ui(uic_sources ${vole_module_ui_sources})
qt4_add_resources(rcc_sources ${vole_module_rcc_sources})
You know, the usual stuff.
Five man weeks later you may probably get it run under Windows, while under GNU/Linux it is three commands in the shell.
You might have an easier time configuring Qt Creator with OpenCV. This post shows how to achieve that, step-by-step! It displays several screenshots to aid in the process too.
I'm running OSX 10.6 (Snow Leopard), Qt 4.6, VTK 5.4, and Cmake 2.8. I installed Qt, then VTK and Cmake. I configured VTK to use QT 4.6 (turned on VTK_USE_GUISUPPORT and VTK_USE_QVTK). The configuration and installation worked painlessly but if I run Cmake with Qt references the compilation fails during the subsequent make process because of failed dependency resolution.
As an example, I tried to build the Qt ImageViewer example (VTK/Examples/GUI/Qt/ImageViewer) and it failed to find qapplication.h (and all other qt headers). Any ideas about why this might be happening would be greatly appreciated!
CMake finds Qt by looking for qmake (ironic, eh?). Make sure qmake is in your path.
Also, make sure VTK and Qt 4.6 were compiled with the same version of gcc/g++. Weird runtime errors (like cout not working) can result.
First you should set DESIRED_QT_VERSION to 4. When it's ready, you could chose QT_QMAKE_EXECUTABLE to your qmake binary.
I find that the CMakeCache.txt in your build folder for cmake tends to have all the necessary diagnostics info for stuff like this. Almost certainly there's a string field for the include path that is blank right now due to not being found.