Anton,
I hope you will get some inspiration from the macro below.
To use it, do
Root > .L zoom.C
Root > zoom()
You can use the normal zoom on the x axis of the histogram
in the top pad. The histogram in the second pad will be automatically
redrawn in the second pad when you release the mouse.
You can implement a different logic to react to other values of event.
You can also look at $ROOTSYS/tutorials/exec2.C
Rene Brun
//--------------file zoom.C
TH1F *h1, *h2;
TPad *pad1, *pad2;
void zoom() {
h1 = new TH1F("h1","h1",100, -4,4);
h2 = new TH1F("h2","h2",1000,-4,4);
for (Int_t i=0;i<10000;i++) {
h1->Fill(gRandom->Gaus(0,1));
h2->Fill(gRandom->Gaus(0,1));
}
TCanvas *c1 = new TCanvas("c1","test zoom2",700,900);
c1->Divide(1,2);
c1->cd(1);
pad1 = gPad;
h1->Draw();
gPad->AddExec("ex","zoompad2()");
c1->cd(2);
pad2 = gPad;
h2->Draw();
}
void zoompad2() {
int event = gPad->GetEvent();
if (event != 11) return;
TObject *select = gPad->GetSelected();
if (!select) return;
TAxis *axis1 = h1->GetXaxis();
Int_t binmin = axis1->GetFirst();
Int_t binmax = axis1->GetLast();
Float_t xmin = axis1->GetBinLowEdge(binmin);
Float_t xmax = axis1->GetBinLowEdge(binmax);
TAxis *axis2 = h2->GetXaxis();
Int_t newmin = axis2->FindBin(xmin);
Int_t newmax = axis2->FindBin(xmax);
axis2->SetRange(newmin,newmax);
pad2->Modified();
pad2->Update();
}
On Sun, 27 Feb
2000, Anton Fokin
wrote:
> Rene,
>
> I meant two pads and mouse zoom. Of course it is trivial to do in the solid
> code :) The problem is that I have checked zooming in root and do not see a
> straightforward way to catch a mouse zoom event and use it to zoom the
> second histogram.
>
> -----Original Message-----
> From: Rene Brun [mailto:brun@pcbrun.cern.ch]
> Sent: Sunday, February 27, 2000 9:38 AM
> To: Anton Fokin
> Cc: Rene Brun; roottalk@pcroot.cern.ch
> Subject: Re: Zooming two histograms in sync
>
>
> Anton,
>
> Assume TH1 *h1 in TPad *pad1 and h2 in pad2, do
> h1->GetXaxis()->SetRange(firstbin,lastbin); pad1->Modified();
> h2->GetXaxis()->SetRange(firstbin,lastbin); pad2->Modified();
> canvas->Update();
>
> Rene Brun
>
>
> On Sat, 26 Feb 2000, Anton Fokin wrote:
>
> > Hi rooters,
> >
> > I have two histograms in two pads in a canvas and I zoom histograms in
> sync,
> > i.e. if I zoom the upper one, the lower one should also zoom to the same
> > range. (Imagine how it is important for time series applications). What is
> > the best way to implement it?
> >
> > Best regards,
> > Anton
> >
> >
>
>
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