Right or left alignment of legend header

[Haidar]

Hi ROOTers,
I would like to set right alignment for the header of my legend. As far as I read from root page, only center alignment is available like this

leg->SetHeader("my legend title", "C");

Is there anyway to align it to the left or right with an option like “R” for right and “L” for left?

Kind regards,
Haidar.

[dastudillo]

From the documentation, you can set the alignment first for the whole legend (which includes the header), and then set alignment entry by entry; thus, you can first set the alignment you want for the header (don’t change it when creating the header) and then change the alignment of the other entries; eg:

void test() {
   gStyle->SetOptStat(0);
   TCanvas *c4 = new TCanvas("c", "c", 600,500);
   TH1D *hpx = new TH1D("hpx","This is the hpx distribution",100,-4.,4.);
   hpx->FillRandom("gaus", 50000);
   hpx->Draw("E");
   hpx->GetYaxis()->SetTitle("Y Axis title");
   hpx->GetYaxis()->SetTitleOffset(1.3); hpx->GetYaxis()->CenterTitle(true);
   hpx->GetXaxis()->SetTitle("X Axis title");
   hpx->GetXaxis()->CenterTitle(true);
 
   TH1D *h1 = new TH1D("h1","A green histogram",100,-2.,2.);
   h1->FillRandom("gaus", 10000);
   h1->SetLineColor(kGreen);
   h1->Draw("same");
 
   TGraph *g = new TGraph();
   g->SetPoint(0, -3.5, 100 );
   g->SetPoint(1, -3.0, 300 );
   g->SetPoint(2, -2.0, 1000 );
   g->SetPoint(3,  1.0, 800 );
   g->SetPoint(4,  0.0, 200 );
   g->SetPoint(5,  3.0, 200 );
   g->Draw("L");
   g->SetTitle("This is a TGraph");
   g->SetLineColor(kRed);
   g->SetFillColor(0);

   TLegend *leg = new TLegend(0.5, 0.5, .95, .7);
   leg->SetTextAlign(32);
   leg->SetHeader("my legend title");
   TLegendEntry *le1 = leg->AddEntry(hpx, "hpx", "l");
   TLegendEntry *le2 = leg->AddEntry(h1, "h1", "l");
   TLegendEntry *le3 = leg->AddEntry(g, "graph", "l");
   le1->SetTextAlign(12);
   le2->SetTextAlign(22);
   // if we don't change le3, it keeps the alignment of leg (32 in this case)
   leg->Draw();
}

[Haidar]

Thank you so much!! It is exactly what I am looking for