TExec.cxx

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// @(#)root/base:$Id$
// Author: Rene Brun   29/12/99

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

#include "Riostream.h"
#include "TROOT.h"
#include "TExec.h"

ClassImp(TExec)

/** \class TExec
TExec is a utility class that can be used to execute a C++ command
when some event happens in a pad.
The command in turn can invoke a C++ macro to paint graphics objects
at positions depending on the histogram or graph contents.

### Case 1:

The TExec object is in the list of pad primitives (after exec.Draw()).
When the pad is drawn, the TExec::Paint function is called. This function
will execute the specified command.
The following example uses the services of the class Aclock created
in `$ROOTSYS/test/Aclock.cxx`.
This examples uses a TTimer to redraw a pad at regular intervals (clock).
When the clock is updated, a string with the current date&time is drawn.
~~~ {.cpp}
{
   gSystem->Load("$ROOTSYS/test/Aclock");
   Aclock ck(400);
   gPad->SetFillColor(5);
   TDatime dt;
   TText t(.5,.3,"t");
   t.SetTextAlign(22);
   t.SetTextSize(.07);
   t.SetTextColor(4);
   t.Draw();
   TExec ex("ex","dt.Set();t.SetTitle(dt.AsString())");
   ex.Draw();
}
~~~

### Case 2:

The TExec object may be added to the list of functions of a TH1 or TGraph
object via hist->GetListOfFunctions()->Add(exec).
When the histogram (or graph) is drawn, the TExec will be executed.
If the histogram is made persistent on a file, the TExec object
is also saved with the histogram. When redrawing the histogram in a
new session, the TExec will be executed.

Example:

Assume an histogram TH1F *h already filled.
~~~ {.cpp}
   TExec *ex1 = new TExec("ex1","DoSomething()");
   TExec *ex2 = new TExec("ex2",".x macro.C");
   h->GetListOfFunctions()->Add(ex1);
   h->GetListOfFunctions()->Add(ex2);
   h->Draw();
~~~

When the Paint function for the histogram will be called, the "DoSomething"
function will be called (interpreted or compiled) and also the macro.C.

### Case 3:

A TExec object is automatically generated when invoking TPad::AddExec.
Each pad contains a TList of TExecs (0, 1 or more). When a mouse event
(motion, click, etc) happens, the pad object executes sequentially
this list of TExecs. In the code (interpreted or compiled) executed
by the TExec referenced command, one can call the pad service functions
such as TPad::GetEvent, TPad::GetEventX, TPad::GetEventY to find
which type of event and the X,Y position of the mouse.
By default, the list of TExecs is executed. This can be disabled
via the canvas menu "Option".
See $ROOTSYS/tutorials/hist/exec2.C for an example.
~~~ {.cpp}
   Root > TFile f("hsimple.root");
   Root > hpxpy.Draw();
   Root > c1.AddExec("ex2",".x exec2.C");
~~~
When moving the mouse in the canvas, a second canvas shows the
projection along X of the bin corresponding to the Y position
of the mouse. The resulting histogram is fitted with a gaussian.
A "dynamic" line shows the current bin position in Y.
This more elaborated example can be used as a starting point
to develop more powerful interactive applications exploiting CINT
as a development engine.

The 3 options above can be combined.
*/

////////////////////////////////////////////////////////////////////////////////
/// Exec default constructor.

TExec::TExec(): TNamed()
{
}


////////////////////////////////////////////////////////////////////////////////
/// Exec normal constructor.

TExec::TExec(const char *name, const char *command) : TNamed(name,command)
{
}

////////////////////////////////////////////////////////////////////////////////
/// Exec default destructor.

TExec::~TExec()
{
}

////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.

TExec::TExec(const TExec &e) : TNamed(e)
{
   TNamed::Copy(*this);
}

////////////////////////////////////////////////////////////////////////////////
/// Execute the command referenced by this object.
///
///  if command is given, this command is executed
/// otherwise the default command of the object is executed
///
/// if the default command (in the exec title) is empty, an attempt is made
/// to execute the exec name if it contains a "." or a "(", otherwise
/// the command ".x execname.C" is executed.
/// The function returns the result of the user function/script.

void TExec::Exec(const char *command)
{
   if (command && (strlen(command) > 1))  gROOT->ProcessLine(command);
   else  {
      if (strlen(GetTitle()) > 0)         gROOT->ProcessLine(GetTitle());
      else  {
         if (strchr(GetName(),'('))      {gROOT->ProcessLine(GetName()); return;}
         if (strchr(GetName(),'.'))      {gROOT->ProcessLine(GetName()); return;}
         char action[512];
         snprintf(action, sizeof(action), ".x %s.C", GetName());
         gROOT->ProcessLine(action);
      }
   }
}

////////////////////////////////////////////////////////////////////////////////
/// Execute the command referenced by this object.

void TExec::Paint(Option_t *)
{
   Exec();
}

////////////////////////////////////////////////////////////////////////////////
/// Save primitive as a C++ statement(s) on output stream out.

void TExec::SavePrimitive(std::ostream &out, Option_t * /*= ""*/)
{
   char quote = '"';
   if (gROOT->ClassSaved(TExec::Class())) {
      out<<"   ";
   } else {
      out<<"   TExec *";
   }
   out<<"exec = new TExec("<<quote<<GetName()<<quote<<","<<quote<<GetTitle()<<quote<<");"<<std::endl;

   out<<"   exec->Draw();"<<std::endl;
}