Function returning a TPad

ROOT
1

I am trying to build a function returning a TPad.
The idea is to fill the TPad with the objects I need to draw and then plot the TPad into a TCanvas.
The problem I have is that the resulting TCanvas seems not to contain the TPad I wanted to plot.

This is a simple working example of my problem:

TPad *getPad() {
  TPad *pad= new TPad("pad","pad",0.,0.,1.,1.);
  TH1D *h = new TH1D("h","h",20,-5.,5.);
  h->FillRandom("gaus");
  pad->cd();
  h->Draw();
  return pad;
}

int padFunc()
{
  TCanvas *c = new TCanvas("c","c",500,500);
  c->cd();
  TPad *pad =getPad();
  pad->Draw();
  c->Update();
}

try to run it on CINT using .x padFunc.cc

Can anybody suggest me what’s wrong with that?

2

see required change below. You must draw the pad before drawing anything in it.

Rene

[code]TPad *getPad() {
TPad *pad= new TPad(“pad”,“pad”,0.,0.,1.,1.);
pad->Draw();
TH1D *h = new TH1D(“h”,“h”,20,-5.,5.);
h->FillRandom(“gaus”);
pad->cd();
h->Draw();
return pad;
}

int padFunc()
{
TCanvas *c = new TCanvas(“c”,“c”,500,500);
c->cd();
TPad *pad =getPad();
c->Update();
}
[/code]

3

Also the following code does it:

TPad *getPad() {
   TPad *pad= new TPad("pad","pad",0.,0.,1.,1.);
   TH1D *h = new TH1D("h","h",20,-5.,5.);
   h->FillRandom("gaus");
   pad->cd();
   h->Draw();
   return pad;
}

void padFunc()
{ 
   TCanvas *c = new TCanvas("c","c",500,500);
   c->cd();
   TPad *pad =getPad();
   c->GetListOfPrimitives()->Add(pad);
}
4

Thanks Rene.

What if I wanted to sub-divide the pad into two other?

I tried writing

TPad *pad=...
pad->Divide(2);
pad->Draw();
...

but it is not working.

I also tried to call

TPad *pad =....
pad->Divide(2);
pad->GetPad(1)->Draw();
pad->GetPad(2)->Draw();
...

but is not working.

5

[quote=“puma”]Thanks Rene.

What if I wanted to sub-divide the pad into two other?

I tried writing

TPad *pad=...
pad->Divide(2);
pad->Draw();
...

but it is not working.

I also tried to call

TPad *pad =....
pad->Divide(2);
pad->GetPad(1)->Draw();
pad->GetPad(2)->Draw();
...

but is not working.[/quote]

Sorry if I didn’t check couet answer before.
His method is working even with multiple pads.
Thank you very much!