Error message: This application failed to start because it could not find or load the Qt platform plugin windows. Reinstalling the application may fix the problem. I've done a lot of searching and none of the solutions I've found worked. I've followed this Deploy an App on Windows - even the quick and dirty method failed. I have the /platforms/qwindows.dll in my app root directory. I've used the dependancy walker app depend.exe we all know and love Error: At least one module has an unresolved import due to a missing export function in an implicitly dependent module. Error: Modules with different CPU types were found. Warning: At least one delay-load dependency module was not found. Warning: At least one module has an unresolved import due to a missing export function in a delay-load dependent module. Frankly I don't understand this. language barrier? It says that there are DLLs missing, DCOMP.dll, API- MS- WIN- APPMODEL- RUNTIME- L.dll, API- MS- WIN- CORE- WINRT - ERROR- L, - L, - ROBUFFER- L, - STRING- L. DLL and API- MS- WIN- SHCORE- SCALING-l.dll, but they are nowhere to be found. Similarily named dlls are included in kernel.dll and MSVCRT.dll. It also mentions IESHIMS.dll, but including it doesn't make a difference. I have following dlls in my folder: /platforms/qwindows.dll icuin53.dll icudt53.dll icuuc53.dll lib EGL.dll (even though my app doesn't use it) libgcc_s_dw2-1.dll libopencv_core2410.dll libopencv_highgui2410.dll libopencv_imgproc2410.dll libstdc+-6.dll IEShims.dll libwinpthread-1.dll Qt5 Core.dll Qt5 Gui.dll Qt5 Widgets.dll Copied from C:\ Qt\ .4\mingw491_32 There's an identical problem with the debug version of the exe, that has *d.dll libraries with it. I am using Qt and Mingw32 on Windows 7 64-bit. The app obviously compiles and runs on my netbook, every other PC gives me the error, however I MUST distribute it. When I.
In my project, I have a set of DLLs I want to load delayed, i.e. on first use instead of on process start. That means I want to use / DELAYLOAD flag of the MSVC linker (see [1] for more explanation) for certain DLLs (not Qt itself). The reason is that some users experience crashes during DLL initilization (which we can't reproduce). A former non- Qt version of the software didn't have that problem, but it used delayed loading, so that might make a difference. Using QMake, I found no way to get delayed loading to work. Does anyone know how to pass / DELAYLOAD to the msvc linker, using qmake features on bypassing qmake? [1].
Yes, you want to use the QLibrary class. It is specifically provided to load shared libraries at runtime. In this case you do not need anything in your.pro file. However, you need to make sure the DLL is available on the target computers. It either needs to be in a location where the system can find it ( PATH on Windows, LD_ LIBRARY_ PATH on Linux, DYLD_ LIBRARY_ PATH on Mac) or you can provide an absolute path from your application. If you look at the documentation you will see how to map a library function to a function pointer in your code so that func1 will point to the function in your library. [ EDIT] Here is a proof-of-concept to load a dll from a temp file generated from a resource. IMO, this is a Really Bad Idea, but it at least works on my Windows 7 machine. If you want to do something similar, you will have to handle cleaning up the temp file, checking for duplicates, etc. foo.cpp, compiled into a shared library include < Qt Core/qglobal.h> extern C Q_ DECL_ EXPORT int foo(int value) return value + 42; bar.pro, notice no reference to foo library SOURCES += main.cpp RESOURCES += resources.qrc main.cpp include < Qt Core> include int main(int argc, char *argv) QCore Application app(argc, argv / Copy resource dll to temporary file. QFile:copy( lib/ Foo.dll, QDir:temp.file Path( Foo.dll / Load the temporary file as a shared library. QLibrary foo_lib( QDir:temp.file Path( Foo.dll typedef int Foo Delegate int Foo Delegate foo = ( Foo Delegate)foo_lib.resolve( foo if (foo) std:cout < foo(13) = < foo(13) < std:endl;.
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