Greyscale

Create grey scale of 200 x 200 boxes.

Author: Olivier Couet
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Monday, September 20, 2021 at 12:51 PM.

In [1]:
TCanvas *c = new TCanvas("grey", "Grey Scale", 500, 500);
c->SetBorderMode(0);

Int_t   n = 200;   // tunable parameter
Float_t n1 = 1./n;
for (int i = 0; i < n; i++) {
   for (int j = 0; j < n; j++) {
      TBox *b = new TBox(n1*j, n1*(n-1-i), n1*(j+1), n1*(n-i));
      Float_t grey = Float_t(i*n+j)/(n*n);
      b->SetFillColor(TColor::GetColor(grey, grey, grey));
      b->Draw();
   }
}
TPad *p = new TPad("p","p",0.3, 0.3, 0.7,0.7);
const char *guibackground = gEnv->GetValue("Gui.BackgroundColor", "");
p->SetFillColor(TColor::GetColor(guibackground));
p->Draw();
p->cd();
TText *t = new TText(0.5, 0.5, "GUI Background Color");
t->SetTextAlign(22);
t->SetTextSize(.09);
t->Draw();

c->SetEditable(kFALSE);

Draw all canvases

In [2]:
gROOT->GetListOfCanvases()->Draw()