Signal/slot in stand-alone program

ROOT
1

hello,

I am a beginner and I tried a simple code to print the coordinates of the mouse. Everything is working well with CINT but when I try the same code in a stand alone program it doesn’t work. The compilation is ok but when I start the application I get the following message:

Error in TQObject::CheckConnectArgs: slot printEvent(int,int,int,TObject*) does not exist

Here is the code:

#include "rootheaders.hh"
#include <TROOT.h>
#include <TPad.h>
#include <TH1.h>
#include <TH2.h>
#include <TCanvas.h>
#include <RQ_OBJECT.h>


/////////////////////////////////////////////////////////////////////
/////////////////////// functions ///////////////////////////////////
//___________________________________________________________________
void printEvent(Int_t event, Int_t px, Int_t py, TObject *)
{
   //  print event type and current cursor position

   TCanvas *c = (TCanvas *) gTQSender;
   TPad *pad = (TPad *) c->GetSelectedPad();
   if (!pad) return;
   printf("event=%d, px=%d, py=%d, ", event, px, py);
   Float_t x = pad->AbsPixeltoX(px);
   Float_t y = pad->AbsPixeltoY(py);
   x = pad->PadtoX(x);
   y = pad->PadtoY(y);
   printf("x=%.3g, y=%.3g\n",x,y);
}


//___________________________________________________________________
int main(int argc, char *argv[])
{
   // simple test of Pad Event Dispatcher
   TApplication app("App", &argc, argv);
   gStyle->SetPalette(1);
   TCanvas *c1 = new TCanvas("c1", "Test of Canvas Event Signal",
                              900, 500);

   TPad *p1 = new TPad("p1","",0.01,0.05,0.49,0.95);
   TPad *p2 = new TPad("p2","",0.51,0.05,0.99,0.95);
   p1->Draw();
   p2->Draw();

   p1->cd();



   TH1F *hist1 = new TH1F("test1", "1-Dim hist filled manually",20, 1, 100);
   hist1->Draw();

   // print mouse coordinates
   c1->Connect("ProcessedEvent(Int_t,Int_t,Int_t,TObject*)", 0,0, "printEvent(Int_t,Int_t,Int_t,TObject*)");
   app.Run();

   return 0;

}

What am I doing wrong?
Thank you for your answers.

2

Hi,

do you have a dictionary for printEvent()? If not, create a header file containing the declaration (not the definition!) of it, i.e. sigslot.h

void printEvent(Int_t event, Int_t px, Int_t py, TObject *);

and a LinkDef.h:

#pragma link C++ function printEvent(Int_t event, Int_t px, Int_t py, TObject *);

and run rootcint on it:

rootcint -f sigslotdict.cxx -c sigslot.h LinkDef.h

Then build sigslotdict.cxx into a shared library that you either link against your main program or better yet dlopen at runtime. Once loaded the slot will be available.

Cheers, Axel.

3

Thank you very much for your answer.
It is working well now.
cheers,
Dala