Change background color only in a region of a TH1

[Ziel_van_brand]

Hi!

If you run this:

vector<Double_t> x = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
vector<Double_t> y = {1, 2, 3, 4, 3, 6, 7, 0, 0, 4};

void test () {

	TCanvas * c = new TCanvas("name", "window", 800, 600);
	c->SetGrid();
	gStyle->SetOptStat(false);
	
	TH1D * h = new TH1D("name", ";angle [#circ];probability [#]", y.size(), 0, y.size());	
	for (Int_t i = 0; i < y.size(); i++)	h->SetBinContent(i + 1, y[i]);
	
	h->SetFillColor(2);
	h->Draw("HIST BAR");
	
	x.clear();
	y.clear();
}

you get this graph:

but I have the need to highlight an area of the graph, so that i looks like this:

How to do that in root?

Thank you!

[Wile_E_Coyote]

One of the possible ways is to add in the end:

	gPad->Modified(); gPad->Update();
	TBox *b =
	  new TBox(7., gPad->GetUymin(),
		   9., (999. * gPad->GetUymax() + gPad->GetUymin()) / 1000.);
	b->SetFillColor(7);
	b->Draw();
	gPad->RedrawAxis(); gPad->RedrawAxis("G");
	gPad->Modified(); gPad->Update();

Of course, maybe @couet knows something more elegant.

[Ziel_van_brand]

Uhm.

I see it works. Quite simple and effective, so that’s ok!
Thank you!

[couet]

@Wile_E_Coyote

Of course, maybe @couet knows something more elegant.

No, it looks fine to me.

[Wile_E_Coyote]

@couet It seems to me that there is no way to redraw the “border” lines (that’s why I couldn’t simply use “gPad->GetUymax()” and I had to lower the top edge of the box). Maybe you could add this feature.

[couet]

Something like that ?

vector<Double_t> x = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
vector<Double_t> y = {1, 2, 3, 4, 3, 6, 7, 0, 0, 4};

void RedrawFrame(){

   auto b = new TBox(gPad->GetUxmin(), gPad->GetUymin(),
                     gPad->GetUxmax(), gPad->GetUymax());
   b->SetFillStyle(0);
   b->SetLineWidth(gPad->GetFrameLineWidth());
   b->SetLineColor(gPad->GetFrameLineColor());
   b->Draw();
}

void ziel () {

   TCanvas * c = new TCanvas("name", "window", 800, 600);
   c->SetGrid();
   gStyle->SetOptStat(false);

   TH1D * h = new TH1D("name", ";angle [#circ];probability [#]", y.size(), 0, y.size());
   for (Int_t i = 0; i < y.size(); i++)   h->SetBinContent(i + 1, y[i]);

   h->SetFillColor(2);
   h->Draw("HIST BAR");
   gPad->Modified(); gPad->Update();

   auto b = new TBox(7., gPad->GetUymin(),
                     9., gPad->GetUymax());
   b->SetFillColor(7);
   b->Draw();
   gPad->RedrawAxis();
   gPad->RedrawAxis("G");
   RedrawFrame();
}

[Wile_E_Coyote]

So, I’ve been thinking about a new option, something like (note: sometimes “BB” or “FB” drawing options are effective so the complete borders may not need to be redrawn):
gPad->RedrawAxis("B"); // redraw "active" Borders / BoundingBox

[couet]

Yes that’s a idea to put it as a new option in RedrawAxis. I was posting it as an example to check if that is the functionality needed. If yes, that code can go in RedrawAxis…

[Ziel_van_brand]

Uhm, so you basically redraw the main pad too in that additional method RedrawFrame()?

This is a bit more polish since it isn’t affected by the canvas size.

Thanks.

[couet]

This idea would be to pout that code in RedrawAxis under the option "F"rame or "B"ox

[couet]

A PR is on the way:

Implement the F option in RedrawAxis to redraw the plots frame

[couet]

This new option is now in master. Thanks for the suggestion.