Demo of Timers.
Simple example illustrating how to use the C++ interpreter to fill histograms in a loop and show the graphics results This program is a variant of the tutorial "hsum". It illustrates the use of Timers.
Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:12 AM.
Float_t progressRatio = 0.;
TSlider *slider = nullptr;
TCanvas *c1 = nullptr;
Definition of a helper function:
%%cpp -d
void hsumUpdate()
{
// called when Timer times out
if (slider) slider->SetRange(0., progressRatio);
c1->Modified();
c1->Update();
}
Arguments are defined.
Int_t nfill=100000;
c1 = new TCanvas("c1","The HSUM example",200,10,600,400);
c1->SetGrid();
Create some histograms.
auto total = new TH1F("total","This is the total distribution",100,-4,4);
auto main = new TH1F("main","Main contributor",100,-4,4);
auto s1 = new TH1F("s1","This is the first signal",100,-4,4);
auto s2 = new TH1F("s2","This is the second signal",100,-4,4);
total->Sumw2(); // store the sum of squares of weights
total->SetMarkerStyle(21);
total->SetMarkerSize(0.7);
main->SetFillColor(16);
s1->SetFillColor(42);
s2->SetFillColor(46);
total->SetMaximum(nfill/20.);
total->Draw("e1p");
main->Draw("same");
s1->Draw("same");
s2->Draw("same");
c1->Update();
slider = new TSlider("slider","test",4.2,0,4.6,0.8*total->GetMaximum(),38);
slider->SetFillColor(46);
Create a TTimer (hsumUpdate called every 300 msec)
TTimer timer("hsumUpdate()",300);
timer.TurnOn();
Fill histograms randomly
Float_t xs1, xs2, xmain;
gRandom->SetSeed();
for (Int_t i=0; i<nfill; i++) {
progressRatio = i * 1. / nfill;
if (gSystem->ProcessEvents()) break;
xmain = gRandom->Gaus(-1,1.5);
xs1 = gRandom->Gaus(-0.5,0.5);
xs2 = gRandom->Landau(1,0.15);
main->Fill(xmain);
s1->Fill(xs1,0.3);
s2->Fill(xs2,0.2);
total->Fill(xmain);
total->Fill(xs1,0.3);
total->Fill(xs2,0.2);
}
timer.TurnOff();
hsumUpdate();
Draw all canvases
%jsroot on
gROOT->GetListOfCanvases()->Draw()