XLib XSendEvent on other applications/process - c++

Question

I have two Libraries: IDA and XIDA.
XIDA handles the event loop, and there is for each application/process, one single event loop.
And these libraries are "connected" via an callback function.
This is working with events inside one single app/process...
Now I noticed that I could send an event from one app to an other. What it needs was a window handle from another app. So I coded a DBus message, with what I can receive one...
This is working too, but it looks like that the receiver of XSendEvent() can only use functions and its parameters, no member variables!
In the hpp:
Window mSection;
Window Section(){
return 0; // This is working
}
Window Section_A(){
return this->mSection; // This raises a memory access error
}
int CheckEvents( IDA_A *vIDA_A, XEvent vEvent);
static int Section_EventCallback(void* this_ptr, XEvent vEvent){
IDA_A* nIDA_A = NULL;
int nRet = 1;
try{
nIDA_A = static_cast < IDA_A* > (this_ptr);
} catch (...) { return 0; }
cout << "TEST " << nIDA_A->Section() << endl; // This is working, also with any other function
cout << "TEST " << nIDA_A->mSection << endl; // This raises a memory access error, also with any other member variable
cout << "TEST " << nIDA_A->Section_A() << endl; // This also raises a memory access error
nRet = nIDA_A->CheckEvents(nIDA_A, vEvent);
nIDA_A = NULL;
return nRet;
}
In the cpp:
int IDA_A::CheckEvents(IDA_A *vIDA_A, XEvent vEvent) {
Window nWindow = vEvent.xany.window;
cout << "TEST " << " -- " << nWindow << endl; // This is working
cout << "TEST " << " -- " << this->mSection << endl; // This raises a memory access error
return 1;
}
What does it needs to use also member variables?
Regards
Earlybite
------------------------ EDIT: ----------------------------
This is the part of XIDA where XSendEvents() arrives (after calling from inside the event loop):
int XIDA_A::Send_To_Callback(XEvent vEvent){
for(int i = 0; i < (int) this->mVecEvCallback.size(); i++){
if( *this->mVecEvCallback[i].pWindow == vEvent.xany.window ){
if( vEvent.type == ClientMessage ) {
cout << "THIS XIDA CLIENT " << this->mIdent << endl;
}
s_EventCallback nEvCallback;
nEvCallback = this->mVecEvCallback[i];
nEvCallback.Callback (nEvCallback.this_Ptr, vEvent);
return 1;
}
}
return 0;
}
And to this point, it is working, also member variables. But nevermore in IDA, where the Callback is going to.
But it is the same process!
And e.g. with DBus it is working...
I really would like to know the reason!

Answer 1

SOLVED.
I found the error...
This
cIDAMessage nMsg;
nMsg.Msg_Type = IDAMsg_EventCallback;
nMsg.Lng_Send[0] = 0;
nMsg.Para_Void[0] = (void*) &this->mSection;
nMsg.Para_ThisPtr = (void*) this;
nMsg.Para_CallbackPtr = (void*) &this->Section_EventCallback;
this->XIDA_Callback(this->mXIDA_A_Ptr, &nMsg);
is a part of the init.
And I had forgotten to set
nMsg.Para_ThisPtr = (void*) this;
But what I still do not understand...
static int Section_EventCallback(void* this_ptr, XEvent vEvent){
IDA_A* nIDA_A = NULL;
int nRet = 1;
try{
nIDA_A = static_cast < IDA_A* > (this_ptr);
} catch (...) { return 0; }
nRet = nIDA_A->CheckEvents(nIDA_A, vEvent);
nIDA_A = NULL;
return nRet;
}
Here comes/came the pointer with NULL.
Why wasn't nIDA_A not NULL, or why wasn't there raised an error, because static_cast cannot cast with NULL?
And why were functions working, but not member variables?
You know what I mean?