c++ - SetWinEvent on a separate Class -

i have little problem qt , here code :

sessionsnatcher.h:

#ifndef sessionsnatcher_h #define sessionsnatcher_h  #include <windows.h> #include <qthread> #include <qtcore> #include <qdebug>   class sessionsnatcher : public qthread { public:     sessionsnatcher();     ~sessionsnatcher();     void run();     void setpid(int pid);     void settid(int tid);     int getpid();     int gettid();     hwnd getcoproductcontrol();  private:      //hwnd getcoproductcontrol();     void callback sessionsnatcher::handler(hwineventhook hook , dword event , long idchild , long idobject , dword dweventthread , dword dwmseventtime);     hwineventhook hook;     int pid , tid;  };  #endif // sessionsnatcher_h 

sessionsnatcher.cpp :

#include "sessionsnatcher.h"  sessionsnatcher::sessionsnatcher() {  }  sessionsnatcher::~sessionsnatcher() {     unhookwinevent(hook); }  void callback sessionsnatcher::handler(hwineventhook hook , dword event , long idchild , long idobject , dword dweventthread , dword dwmseventtime) {  }  void sessionsnatcher::run() {     hook = setwineventhook(event_system_foreground , event_system_foreground , null , &sessionsnatcher::handler , pid , tid , winevent_outofcontext); }    hwnd sessionsnatcher::getcoproductcontrol() {     hwnd tpanel = findwindow(l"tpanel" , null);     return tpanel; }  void sessionsnatcher::setpid(int pid) {     pid = pid; }  void sessionsnatcher::settid(int tid) {     tid = tid; }  int sessionsnatcher::getpid() {     return pid; }  int sessionsnatcher::gettid() {     return tid; } 

and keep getting error :

d:\tt\sessionsnatcher.cpp:25: error: c2664: 'hwineventhook setwineventhook(dword,dword,hmodule,wineventproc,dword,dword,dword)' : cannot convert argument 4 'void (__stdcall sessionsnatcher::* )(hwineventhook,dword,long,long,dword,dword)' 'wineventproc' there no context in conversion possible 

before using "handler" instead of "&sessionsnatcher::handler" had problem saying member , cant used that. cant work out. worked on visual studio when tried , had cast (wineventproc)handler , think since im using separate class cant anymore.

any tips ?

you have fallen victim hidden this parameter in every non-static class methods. modern solution use std::bind, won't c-based api or c++ api predates c++11.

the typical solution when std::bind isn't available free function or static method

1. meets prototype need supply,
2. maps callback object, and
3. invokes desired method on object found in 2.

often win32 api calls have pointer user argument can use make easy: cast pointer sessionsnatcher * , call function. don't see user argument in wineventproc's parameter list, you'll have creative , map 1 of event ids or handles wineventproc provide , uniquely identifies sessionsnatcher.

or if have 1 sessionsnatcher can write function use 1 sessionsnatcher.

here generic example:

#include <iostream> #include <map>  typedef int (*funcp)(int id, int p1, int p2); // using typedef instead of using on purpose because that's what'll in // windows api  class test { private:     static std::map<int, test*> tests; // our map of id -> test objects     int id; // test's id. included proof public:     test(int id):id(id)     {         tests[id] = this; // put in map. in real world test collision first     }      // function called     int func(int p1, int p2)     {         (void) p1;         (void) p2;         std::cout << "called func " << id << std::endl;         return 0;     }      // static method can called api     static int staticfunc(int id, int p1, int p2)     {         // object , call non-static method         // recommend at() instead of [] because catchable exception         // rather crash on null pointer if id unknown.         return tests.at(id)->func(p1, p2);     } };  // allocating storage static map std::map<int, test*> test::tests;  // function mocking api. takes function , identifier used called function int caller(funcp func,            int id) {     return func(id, 100, 20); // calls function }  // tester int main(void) {     test a(1); // create test     test b(2); // create test      try     {         caller(test::staticfunc, 2); // call test 2 through api         caller(test::staticfunc, 1); // call test 1 through api         caller(test::staticfunc, 10); // throw exception on unknown id     }     catch (std::exception &e)     {         std::cout << "failed call: " << e.what() << std::endl;     } } 

typical output:

called func 2 called func 1 failed call: map::at 

"map::at" isn't of exception message, can converted useful log message. @ rate beats segfault no information.