dll using qt

hi there,

i'm not really a qt newbie - but in this field here i am :o

i have to develop a dll (and a so, later, too) which uses qtcore. in particular i need container classes, threads and mutexes as well as signals and slots. i don't need any gui stuff.

my first question: i have qt 4.3.3 installed, as well as the vs 2005 integration. now, when i choose 'new project' and specify 'qt library', i obviously get a dll project and i can build it - but - where is DllMain() :confused:

do i have to add the code?

my second question: do i have to have a QCoreApplication? What if the caller of my dll runs it's own event loop?

thanks for any advice,

sepp

creating library
creating dlls with Qt is very simple, you need to add export keywords to export needed entities, but there are several rules:
first of all you need to create some kind of global h-file for your library-project with import/export variables, it should look like this example

Code:

---

#ifndef MYWIDGET_GLOBAL_H
#define MYWIDGET_GLOBAL_H
 
#include <QtGlobal>
 
#ifdef MYWIDGET_STATICLIB 
#  undef MYWIDGET_SHAREDLIB 
#  define MYWIDGET_EXPORT 
#else 
#  ifdef MYWIDGET_MAKEDLL 
#   define MYWIDGET_EXPORT Q_DECL_EXPORT 
#  else 
#   define MYWIDGET_EXPORT Q_DECL_IMPORT 
#  endif 
#endif
 
#endif//MYWIDGET_GLOBAL_H

---

then as I said earlier you need to add export keyword before class declaration, e.g.

Code:

---

....
#include "mywidget_global.h"
...
class MYWIDGET_EXPORT MyWidget: public QWidget
{
....
};

---

that's all what you need to add in source file.
then you need to prepare correct pro and pri files.
* pri-file should contain the next lines

Quote:

---

MYWIDGET_LIB = -llibmywidget

INCLUDEPATH += $$TOP/libmywidget/include
DEPENDPATH += $$TOP/libmywidget/src

---

where $$TOP is start path.
* pro-file should contain the next lines

Quote:

---

CONFIG += dll
TEMPLATE = lib
DESTDIR = lib

unix:CLEAN_FILES += $(DESTDIR)lib$(QMAKE_TARGET).*
win32:CLEAN_FILES += $(DESTDIR)$(QMAKE_TARGET).*

TOP = ../..

TARGET = libmywidget
include(libmywidget.pri)

contains(CONFIG, staticlib) {
DEFINES += MYWIDGET_STATICLIB
} else {
DEFINES += MYWIDGET_SHAREDLIB
}

win32 {
DEFINES += MYWIDGET_MAKEDLL
}

---

and that's all! now, when you call qmake/(n/mingw32-)make you'll get shared library.
how to attach this library to another project?
you just need to add following lines in pro-file of needed project which will use created library

Quote:

---

...
TOP = ..

include($$TOP/libmywidget/libmywidget.pri)

LIBS += -L$$TOP/libmywidget/lib/ $$MYWIDGET_LIB
...

---

and then build this project.
PS. attach contsins complete example.

Quote:

---

Originally Posted by spirit

how to attach this library to another project?
you just need to add following lines in pro-file of needed project which will use created library

and then build this project.
PS. attach contsins complete example.

---

ok, thanks. so i probally don't need a DllMain()... i'll find out.

however, the application which will use my library will not be a qt project. therefore, again: do i need a QCoreApplication in my dll to use signals/slots, qt threads/mutexes and qt container classes? may this conflict with the applications own event loop?

thanks,

sepp