I am trying to create a project assosiated with the SimConnect SDK.
I am new to QT, and in Visual Studio, I just had a SimConnect.h file, a .lib file, and a .dll file, and I managed to make it work. Now I am trying to create a C++ widget project, using the same SDK, but in QT.
I put the header file in my QT project's folder, where the other default code and header files are located, and then I went to the project and added them as existing files, as I read in Google. I'm having problems with the actual library.
I've been searching Google for a guide on how to add a library file to the project, I did some things I saw on the internet, like the LIBS line for example, but I probably did it wrong, even though it looked very simple.
I am not sure where to drop my dll/library files in the project directory, maybe the problem is I always put them in the wrong spot.
The furthest I got to, was an error message saying "Unresolved external symbol", and a red writing saying ".obj file not found" on every function I tried to use from the SimConnect functions, which probably means QT couldn't find my library/dll file.
I also tried to add the libraries from the "Add library" option in the project, but that didn't work too.
EDIT: it also warns "warning: LNK4272: library machine type 'X86' conflicts with target machine type 'x64'" maybe it has to do something with it.
(Posted on behalf of the OP).
Solved! My problem was my machine was set to 64bit, while the library was set to 32bit, so I downloaded the 32bit kit, and ran the project through that, and it worked!
Related
I use QtCreator + mingw.
I have compiled QSQLITE2 plugin. I simply entered plugin directory in Qt source code:
c:\Qt\Qt5.2.0\5.2.0\Src\qtbase\src\plugins\sqldrivers\sqlite
and I built it with my sqlite 2.8.17 that I have locally (as dll and header):
qmake "LIBS+=-Lc:\projects\lib -lsqlite" "INCLUDEPATH+=c:\projects\include"
make
make install
Everything builds okay.
Now, I have another DLL (also implemented as Qt plugin, a custom one), which makes use of QSQLITE2 Qt plugin. My own dll is also linked to sqlite.dll. So it looks like this:
my.dll depends on sqlite.dll
%QT_PLUGINS%\qsqlite2d.dll depends on sqlite.dll
my.dll uses qsqlite2d.dll through Qt's plugin engine
myApp.exe loads my.dll
Problem is that my application cannot load my.dll, because of invalid location access or something like that. I don't know any details and that's the problem.
The sqlite.dll is in the application directory when running it.
When I run application in debug mode, it crashes in some assembly file, but in stack trace I can see that it's somewhere inside sqlite.dll, in sqlite_step symbol. That's all I know.
Note 1) I have another plugin dll, the my3.dll, which uses QSQLITE plugin (it's for sqlite3) and is linked with sqlite3.dll and this one loads just fine. I have compiled QSQLITE plugin myself as well (even there was the one provided with Qt, that's because Qt linked statically to sqlite3 and I wanted it to link dynamically to sqlite3.dll).
Note 2) Both plugins work just fine under Linux.
Any hints what might be wrong? What else can I check?
EDIT:
I've just performed a test: I deleted my.dll from plugins to avoid loading it at all. Then I added code to main.cpp:
QSqlDatabase::addDatabase("QSQLITE2", ":memory:");
Thing is, that it also crashed, with the very same stack trace (at this very line, I debugged it). Thus I think there's something wrong with sqlite2 Qt plugin, but I'm still unable to tell what. I looked up for other sqlite.dll, I just downloaded the one from sqlite.org: http://www.sqlite.org/sqlitedll-2_8_17.zip - so it's official build, but it's the exactly the same file I had and it also fails the same way.
It turned out that qsqlite2d.dll cannot be linked sqlite.dll, because sqlite.dll is not compiled in debug mode. After recompiling application in release mode (thus using qsqlite2.dll, not qsqlite2d.dll), the plugin loads correctly and works.
This makes sense, but just one more thing that bugs me - qsqlited.dll (for sqlite3) had no problem linking with sqlite3.dll. No matter if I compiled debug or release - the single sqlite3.dll worked with both debug and release plugins. Anyone has an idea how is that possible? Please comment if you do, I'd appreciate it.
I have been working on a Qt OpenGL project for a bit now for some school work. I had to re-build Qt 5.0.1 for my windows machine so I could use OpenGL proper. At the end of this project I need to turn over the files and any executables, so I figured I could take the release .exe and stick it in a .zip for use.
I followed instructions online of making sure I place any needed .dll's into the .exe's dir. For my project there are 10:
icudt49, icuin49, icuuc49, libEGL, libGLESv2, Qt5Core, Qt5Gui, Qt5OpenGL and Qt5Widgets
I took these files all from:
C:\Qt\Qt5.0.1\5.0.1\msvc2010\bin
on my system.
Issue is the .exe will run and I get the UI and all. But the OpenGL scene is just black. I can still click objects in the scene, evidently zoom in and out and all that. I assume thats just the Qt translating the commands still. But nothing is visible. I'm unsure what the problem can be because it all works fine when launched from the creator.
EDIT: So, with all the dlls in the release folder, running the project from within creator will also have a black screen, when I remove them, it runs well. So perhaps one of the dll's is just wrong?
Also:
I looked online about publishing with Qt Creator and found not too much aid, said I should start from completely rebuilding Qt Creator staticly, but I'm sure the guide I had followed did this, however I still can't publish from the build menu, so I stuck with the above method.
I suggest, that you open every of the DDLs in your Zip file with Dependency Walker (http://www.dependencywalker.com/). It should display information about dependencies from one of your QtXXX.dll files to other files. If one of the dependencies is missing, you know where to look next. You can also try to open your executable with Dependency Walker. I haven't used the program for a long time so I don't remember if opening an executable is the only way it works. Anyway, here are the reasons why you might want to use the tool: http://www.dependencywalker.com/help/html/overview_1.htm
This question might also be helpful:
At least one module has an unresolved import due to a missing export function in an implicitly dependent module
Good luck!
So the ultimate issue was the use of the correct DLLs. Using something like DependenyWalker can help you to note which DLLs may be missing, however it did nothing in my case.
I had installed Qt once, and also rebuilt, uninstalled and re-installed it. However all the libraries it was calling from as no longer in C:\Qt\Qt5.0.1\5.0.1\msvc2010\bin as expected, it was calling from the github repository where I built it C:\Users\User\Documents\GitHub\qt5. Once this is sorted out, it still required a framework folder and then it works as expected.
1) Copy the correct DLL files to the release folder of the build.
2) Create a folder in the same dir as the .exe named "platforms". (Note: elsewhere has said create plugins>platforms, but this will not work with newer Qt versions)
3) From the same source you got the other DLLs, copy qwindows.dll to the platforms folder you created.
4) Run the executable and enjoy.
As long as the system you're running on is capable of your OpenGL structure, it should be fine.
Guys I've written app in qt and when trying to run it (double click on *.exe) I'm getting error that this application cannot start because qtnetwork4.dll isn't available. I've searched my drive and I found few files with this name (and copied one by one every time trying to run my app) but none of them seems to work. How can I solve it?
place into your *.exe - folder appropriate dll-s from %QT_PATH%\bin\
There is an app called Dependency Walker that will let you know what functions in qtnetwork4.dll are being used in your program. It can be found at the following:
http://www.dependencywalker.com/
All of the DLLs your program use will be from the same installation as the qmake.exe that is used to compile the program. If you are using Qt Creator you can see where the qmake.exe your using is located by going to:
tools->options->Qt4
Get the DLLs that are located at the path displayed here to make sure they will work with your program.
On windows, DLL are looked for in folder where executable lies, then using "PATH" environenment variable.
In your case, you want to put your dll along your executable, taking them from the sdk you're using to compile
The following page provides a lot of additional information on the subject (example, plugins, strategy for building installers)
To force using QtNetwork and linking it, you have to put
QT += network
in your poject file.
If you're sure you're not using it, you can use
QT -= network
Until now my Visual Studio 2008 debugger gracefully stepped into Qt library code when I pressed F11. After upgrading Qt to the latest version and changing QTDIR, F11 does not step into library code anymore. Any clues how to make the debugger smart again?
Activate the modules list, Debug - Windows - Modules, to see what libraries are loaded and if debug symbols are loaded for those libraries. Note that you need to have the debugger active on your process to be able to do this.
In debug mode, the Qt libraries should be suffixed by d. QtCored4.dll for instance. If you see QtCore4.dll on the list, you have linked to the wrong libraries. If it does say QtCored4.dll but under Symbol Status there is something different than Symbols loaded., then that's the reason. You can manually load the symbols here by right clicking on the dll and selecting Load Symbols. It asks for the Pdb file after clicking that.
You can add more pdb file locations, if they weren't loaded but exist, from Tools - Options - Debugging(tree) - Symbols(tree). If you want the symbols to be automatically loaded.
Should it give some error, that the pdb file doesn't match the binary or something like that, you should re-build your Qt debug version, unless you have more pdb files to try. Use the Visual studio command prompt and go to the Qt directory, run configure and nmake. It takes a while, possibly some hours. There was some switch to only build debug version but i forgot where it goes. Note that the build might fail and after that it's a lot of fun www.google.com searches. The best bet might be to get the source only package, I forgot where to get that and it's not easily found. If you know where to get it, tell me please. I vaguely remember that there might be some other way to build the debug version, but this is the only one i know for sure.
#0xbaadf00d's recommendation to "open the Debug/Windows/Modules view" for verifying which modules have loaded successfully and which are not loaded is extremely useful.
Here is a summary of what I check when I need to step into Qt source code:
The DLLs must be for the Qt version in developer's Qt kit
The Qt .pdb files must be present in Qt kit's folders: bin, lib, plugins/platforms, plugins/qmltooling
Visual Studio Tools/Option/Debugging/Symbols needs paths to .pdb files:
If qt.conf file is used, must point to correct bin folder
If target is WinCE or WEC2013 and using HKLM\Loader\SystemPath, you must specify path to DLLs in SystemPath variable
Set the location for the source files in the project property pages:
I'm trying to access a MySql database from a Qt application but I get the following error:
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QSQLITE2
I find this very strange cause I have libqsqlmysql.so on my Qt folder. I have even tried to compile the MySql driver as a static plugin and add it to my .pro file as:
QTPLUGIN += qsqlmysql
But this also generates the same runtime error (it must've found the plugin cause there's no error compiling the application)
What am I missing? I would like to avoid having to compile Qt from source cause this will have to work seamlessly on the deploy machines as well.
BTW: Even though I'm developing and testing on Linux I will need to support Windows. Will I experience this same issue on Windows? How can I compile and link the MySql driver in both Linux and Windows?
The solution:
After following #Sergey's recommendations I did an strace of the application redirecting the output to grep so I could search for 'mysql' and for my surprise the application wasn't looking for the plugin at QTDIR/plugins/sqldrivers where I had libqsqlmysql.so, it was looking at QTDIR/lib. After copying the plugin to the lib folder the MySql connection worked.
Try opening the shared library with dlopen() and see if it loads and if not, what dlerror() tells you. I always run into similar problems on Windows. LoadLibrary()/GetLastError() saved me numerous times (last time it was because of a wrong version of some libiconv/libintl DLL). Running ldd on the plugin may also help.
If dlopen() works fine, try to load the plugin with QPluginLoader. If it doesn't load, then check the buildkey of the plugin. I usually do it the dirty way by running strings on the plugin and then looking for strings like "buildkey" or "QT_PLUGIN_VERIFICATION_DATA". Just looking at the build key and around it may give you an idea. For example, you may realize that you have compiled your plugin in the release mode while your application is compiled in the debug mode. In such case the build key won't match and the plugin won't load. Everything in the build key must match your configuration. Note that the version and the build key are checked differently: the build key must match exactly (or match some black magic called QT_BUILD_KEY_COMPAT), but in the version only the major version must match exactly, the minor version must be the version of Qt the plugin was compiled with or later and the patch level is ignored. So if your plugin was compiled with Qt 4.x.y then it will work with Qt versions 4.z.* where z>=x. This actually makes sense.
If the build key looks okay (which is unlikely if you got to this point), you may wish to look at QLibraryPrivate::isPlugin() source code to figure out what's wrong, but that doesn't look like an easy task to me (although running this in a debugger may help).
If QPluginLoader does load the plugin, check if it is in the right directory and has correct permissions. If you still didn't solve the problem by this point, it's time to look at the SQL module source code that actually loads these plugins. But it is extremely unlikely. I ran into this problem many, many times and it was always either the library not loading or the build key not matching.
Another way to go after QPluginLoader loads the plugin successfully is to use strace to figure out whether the program at least tries to open the plugin file. Searching for something like "sqldrivers" or "plugins" in the strace output should also give away the directory where Qt is searching for its plugins and specifically SQL drivers.
Update
Is it possible to compile the driver as a static plugin and don't worry about anything? Let's try:
d:\Qt4\src\plugins\sqldrivers\psql>qmake CONFIG+=static LIBS+=-Ld:/programs/Post
greSQL/lib INCLUDEPATH+=d:/programs/PostgreSQL/include
d:\Qt4\src\plugins\sqldrivers\psql>make
It compiles fine and now I got libqsqlpsql.a (release) and libqsqlpsqld.a (debug) in QTDIR/plugins/sqldrivers (it is the right place on Windows). I am using PostgreSQL driver here, but I don't think it will be any different for MySQL which I just don't have installed. Ok, let's compile some real program with it:
d:\alqualos\pr\archserv>qmake QTPLUGIN+=qsqlpsql PREFIX=d:/alqualos LIBS+=-Ld:/g
nu/lib INCLUDEPATH+=d:/gnu/include LIBS+=-Ld:/programs/PostgreSQL/lib LIBS+=-lpq
Note that I had to manually link to libpq, otherwise the linker would complain about undefined references. The funny thing is, qmake knows that qsqlpsql is located in QTDIR/plugins/sqldrivers and sets compiler and linker options accordingly. So it still needs to be in the right place to work, only you don't have to worry about your users running into the same problem as it is only used during compilation. An alternative would be to just use LIBS+=-Lpath/to/plugin LIBS+=-lqsqlpsql instead of QTPLUGIN+=qsqlpsql, at least the docs say that it should work, but I haven't tested it.
In order for the application to actually use the plugin I had to put the following in my main unit (CPP file):
#include <QtPlugin>
Q_IMPORT_PLUGIN(qsqlpsql)
It works! Also, from what I've been able to figure out from the sources, the build key and the version are checked only when a plugin is dynamically loaded (all the relevant stuff is in the QLibrary's private class, not even QPluginLoader's). So the resulting executable may (or may not, depending on the binary compatibility) work even with different versions and builds of Qt, although using it with older versions may trigger some bugs that were fixed later.
It is also worth noting that the order for loading SQL drivers is this: use the driver statically linked into Qt if available, then look for a driver registered manually with QSqlDatabase::registerSqlDriver(), then look for a driver statically imported into the application (the way described above), and finally try to load a shared plugin. So when you link statically, your users won't be able to use dynamically linked drivers they may already have, but will be able to use drivers linked statically into Qt (like in Ubuntu).
I compiled QT first and then realised that I need mysql as well. So I compiled mysql plugin by
executing following command in QT-DIR\src\plugins\sqldrivers\mysql folder.
Mysql plugin compile command
qmake "INCLUDEPATH+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\include)" "LIBS+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\lib\libmysql.lib)" mysql.pro
Plugings are then created in created in folder QT-DIR\plugins\sqldrivers.
However, when I tried to use it in my code. It failed with following error.
Error msg
QSqlDatabase: QMYSQLDriver driver not loaded
Solution
After some googling and checking Path variable I realised that the Mysql server lib
( C:\Program Files\MySQL\MySQL Server 5.5\lib) directory was not in my Path variable. I expect that the dll in this folder are used by the plugin at runtime. After including Mysql server lib in Path variable everything worked smoothly. Hope this information saves some hair on other programmers scalp, as I uprooted quite a few. :D
Last time I looked at this you needed to rebuild Qt from source and include the appropriate MySQL source.
Building Qt from the sources is not hard, it just takes a while. You are likely to have the required tools already.
A possible workaround may be to access the back-end over ODBC instead.
In order for your app to pick up the plugin at runtime, the shared library implementing the MySQL plugin needs to be placed in the correct directory. The best way of determining that directory is to check the output of QCoreApplication::libraryPaths. You can also force specific paths by using a qt.conf file.
Please note that plugins must be placed in subdirectories within the plugin path, and the final part of the path name (i.e., the parent directory of the shared libraries) cannot be changed. SQL drivers need to go in a directory named sqldrivers, i.e. <pluginpath>/sqldrivers. For more details on plugin directories, see How to Create Qt Plugins.
I was experiencing this same issue as well. I've been installing and experimenting with a lot of different Python tools and UIs. I then uninstalled everything python related. I did a fresh install of Python 3.2, PyQT 3.2, and Eric5. No more errors with the QMySQL driver.
well i have had this issue, and after a lot of time, and different tools, i found that QT ( on windows, have not been able to test on Linux.) loads the "QSQLMYSQL.." when requested, but before runtime the lib ("QSQLMYSQL..") file must reside on one of the searched paths (QApp.libraryPaths()) inside a folder called "sqldrivers".. otherwise QT will just ignore the file, even if it is at some other point inside the searched path.
what i did was to monitor the dependency of a sample app, and when i removed the "QSQLMYSQL.." dll from "plugins\sqldrivers\" it failed, but when i maded a folder inside the app folder, called "sqldrivers" and placed the "QSQLMYSQL..." inside there, it loaded.
what i have is mysql 5.5, qt 4.7.4.
hope anyone can use this, and if anyone knows more about it, i would like to know where to find it(http://doc.qt.nokia.com/stable/sql-driver.html, is the closest you can get to the information about the folder structur). :P
This may also happen if your QMYSQL plugin is linked against the "wrong" mysql_client.a or it isn't in the LD_LIBRARY_PATH. I had this problem on OSX because mysql was installed via ports, and I fixed it with:
install_name_tool -change libmysqlclient.18.dylib /usr/local/mysql/lib/libmysqlclient_r.18.dylib libqsqlmysql.dylib