If I compile OpenCV using MinGW MakeFiles in CMAKE.Would I be able to use it on QT that uses Visual Studio Compilers?
Depends - which compiler are you using. If you compile OpenCV using CL (the GnuMakefile calls CL and not GCC) it will work. Compiling using gcc and using this in MSVC/CL will fail.
Each compiler uses another ABI. Don't match them - it will not work (linker will complain for example if you replace DLLs on runtime).
See also: Using MSVC++ .lib files with mingw. Name mangling
http://www.mingw.org/wiki/Interoperability_of_Libraries_Created_by_Different_Compiler_Brands
Related
Just installed QT and trying to build a QT project from inside the QTcreator using Cmake instead of Qmake.
I get the following error:
Starting to parse CMake project, using: "DCMAKE_BUILD_TYPE:STRING=Debug",
"-DCMAKE_CXX_COMPILER:STRING=",
"-DCMAKE_C_COMPILER:STRING=",
"DCMAKE_PREFIX_PATH:STRING=C:/Qt/5.13.1/msvc2015_64",
"DQT_QMAKE_EXECUTABLE:STRING=C:/Qt/5.13.1/msvc2015_64/bin/qmake.exe".
The CXX compiler identification is unknown
CMake Error at CMakeLists.txt:3 (project):
The CMAKE_CXX_COMPILER:
cl
is not a full path and was not found in the PATH.
To use the JOM generator with Visual C++, cmake must be run from a shell
that can use the compiler cl from the command line. This environment is
unable to invoke the cl compiler. To fix this problem, run cmake from the
Visual Studio Command Prompt (vcvarsall.bat).
Tell CMake where to find the compiler by setting either the environment
variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
to the compiler, or to the compiler name if it is in the PATH.
Configuring incomplete, errors occurred!
See also "C:/Users/tany/AppData/Local/Temp/QtCreator-pKrFgC/qtc-cmake-DqmsxZqd/CMakeFiles/CMakeOutput.log".
See also "C:/Users/tany/AppData/Local/Temp/QtCreator-pKrFgC/qtc-cmake-DqmsxZqd/CMakeFiles/CMakeError.log".
CMake Deprecation Warning:
The 'cmake-server(7)' is deprecated. Please port clients to use the
'cmake-file-api(7)' instead.
CMake Project parsing failed.
Now if I use the Cmake-GUI instead, I can configure and generate the project files successfully, after supplying the environment variable CMAKE_PREFIX_PATH.
But I can't get this to work from inside the QTcreator.
Anyone has any experience with using Cmake with QTcreator then please help.
Thank you!
The error message says that your C++ compiler Visual Studio 2015 (64 bits) could not be located. Maybe when you run cmake-gui it finds another C++ compiler like mingw?
In Qtcreator's settings dialog you have a tab showing the detected compilers, and another one with the available kits.
It seems that QtCreator is using a deprecated version of cmake. Update QtCreator to a new (unreleased, as writing this comment, version 4.10.0 is broken) or downgrade cmake to choco.exe install cmake --version 3.11 --force (a newer version might work).
Please also make sure to install jom (as this is the default for QtCreator/CMake on windows).
choco.exe install jom (how can I tell it to use make?)
The deprecation warning is harmless. CMake deprecated the cmake-server and provides a new API for the same purpose now. Qt Creator will support that from 4.11.
The error tells you, that CMake is unable find the cl compiler. cl.exe comes with Visual Studio. Make sure you mark C++ there during the installation process. It is not installed by default anymore.
Alternatively install the MinGW tool chain from the Qt installer. In Qt context it is easier to use than the Visual Studio tool chain.
I'm attempting to use Qt creator to cross-compile a project, but have an issue matching the Qt version and my specified compiler toolchain.
I have created a Kit setting up a Device, selecting my toolchain as the compiler (GCC ARM Linux in this case), but I only have a locally installed system Qt (5.0.2 on Mint x86).
Qt Creator understandably tells me the compiler cannot produce code for the Qt version; all the guides I have found suggest using a Qt compiled for the target platform. This doesn't make sense though - it attempts to run qmake compiled for a different architecture and fails
How do I install or configure/compile a Qt version to work with the cross compiler? Maybe I can modify my existing one to understand this setup?
Thanks
This makes absolutely sense. The advice to use a Qt, which is compiled for your target platform is correct. But this does not mean that you use a Qt that was compiled natively on that target platform. You need to use a Qt, which was compiled with a special cross compiler on your host platform for your target platform. This way qmake and other build tools remain executable on your host, but create configurations for your target.
So, if you have a compiler, which can create ARM code, use it to build your Qt. Then you can create a kit in QtCreator out of this compiler/Qt pair.
Greenflow is right. I would like to add some information. I have cross compiled Qt 5.4.1 on Windows having an ARM Linux as target platform. You just need to configure the build properly. Here's what I did:
./configure -platform win32-g++ -xplatform linux-arm-gnueabihf-g++ .....
So Qt tools (qmake,moc,etc...) were built as Windows binaries and all the libraries were built as Linux binaries. Check for the available platforms in qtbase/mkspecs.
I'm a big fan of StackOverflow because you always have answers for problems, and now is my chance to get advance of it Ö!
I'm trying to use a library which I got in the Internet, its OZCollide. Its suppossed to be crossplatform as it says in its website "Cross-platform, works on Windows, Linux and Macintosh, in fact any platform supporting VisualStudio 6/7 or gcc"
I got all the .h and .cpp, compile them with MinGW as objects (.o) and then link them all using ar. But the problem is when I include and use the library on my project (QT & MinGW) it throws "undefined reference".
I thought the problem could be that library examples only uses Visual Studio, so the library coulnd't be compiled for MinGW, but the website tells other story.
Thanks for your time!
EDIT: Okay I have managed to compile it and use it moving to another computer and compiling makefile. The only one difference is that Computer A had Cygwing and MinGW installed (with Cygwin set up in Windows path) and Computer B only had MinGW.
So I guess the problem was Makefile calling for g++ and Cygwin g++ got called instead of MinGW g++??
If I'm right, whats the difference between Cygwin and MinGW?
if you have experience with CMake, create your own CMakeLists file and import/link this libraries against your project. In this way, you can create projects for MinGW/MSVC/Linux/etc.
Here you'll find a good start with CMake http://www.cmake.org/cmake-tutorial/
I'm searching for a way to force a specific version of QT in a .pro file. To be more specific, I'd like to force qmake to use only QT 5.x version with my project instead of QT 4.x and QT 5.x
Is there a way to do so?
PS: I'm not asking for a way to stop/halt the compile process (aka check QT version, and if lower than 5.x just throw qFatal/equivalent). I'm looking for a way to actually choose which version to use while generating the Makefile with qmake
You can throw a error if a user is running qmake with a version you do not want him to use. ex:
lessThan(QT_MAJOR_VERSION, 5): error("requires Qt 5")
I really doubt you can do this. qmake is a part of framework and goes together with libraries. When you say Qt of specific verion you mean only libraries, but it is not correct.
To use specific version of Qt, you actially need to run different version of qmake. If you are using QtCreator - you should select it in project's options, if not - type absolute path to file qmake. You can find out, which version of Qt qmake uses, you can type qmake --version.
As Amartel wrote in his answer, you should point to the correct qmake version (check it by typing qmake --version in the console)
It might be that your project has been generated using the wrong qmake executable and some files are not removed even if you issue a nmake clean or make clean.
Check that there are no Makefile in the source tree after the clean (these files will typically contain the path to the qt version to use, and if not regenerated correctly will point to the wrong Qt version).
I downloaded C++ libJSON from this link:
And they suggest me to use it as a library. How can I create library using the code they have provided?
you must have installed g++ and make in console/terminal just compile it type make, it will produce libjson.a which is static libary. When you create you C/C++ program you can link it with it g++ -l libjson.a
and in your code include libJSON.h header file.
#include "libJSON.h"
and you can use all functions from that header file.
On windows you must Install MinGW (GNU utilities for Windows), or IDE like DevC++ or Code::Blocks (Code::Blocks use MinGW). You can also use Cygwin unix like environment for windows (but when you compile file in cygwin you can run it only in Cygwin)
In Code::Blocks when you create project you can set additinal library which will be linked with your executable.
i was trying to compile libjson 7.6.1 for Visual Studio 2010. And was facing some difficulties in compiling it. What i did was
Download Libjson
open libjson.vcproj and goto line 240. You will find a missing ">". Type it in and save the file.
Now this can be used to build dynamic and static lib.
A simple thing wasted my couple of hours. Hope it saves some of yours.
This solution also works for more recent versions of Visual studio (e.g. 2015) which otherwise fail to complete the conversion to the mare recent project format.