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Reference Guide
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1/// \file
2/// \ingroup tutorial_hist
3/// \notebook -js
4/// Show the slice of a TH2 following the mouse position.
6/// \macro_image
7/// \macro_code
9/// \author Rene Brun
12void DynamicSlice()
14 // Create a new canvas.
15 TCanvas* c1 = new TCanvas("c1","Dynamic Slice Example",10,10,700,500);
17 //create a 2-d histogram, fill and draw it
18 TH2F *hpxpy = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4);
19 hpxpy->SetStats(0);
20 Double_t px,py;
21 for (Int_t i = 0; i < 50000; i++) {
22 gRandom->Rannor(px,py);
23 hpxpy->Fill(px,py);
24 }
25 hpxpy->Draw("col");
27 //Add a TExec object to the canvas
28 c1->AddExec("dynamic","DynamicExec()");
31void DynamicExec()
33 // Example of function called when a mouse event occurs in a pad.
34 // When moving the mouse in the canvas, a second canvas shows the
35 // projection along X of the bin corresponding to the Y position
36 // of the mouse. The resulting histogram is fitted with a gaussian.
37 // A "dynamic" line shows the current bin position in Y.
38 // This more elaborated example can be used as a starting point
39 // to develop more powerful interactive applications exploiting Cling
40 // as a development engine.
42 TObject *select = gPad->GetSelected();
43 if(!select) return;
44 if (!select->InheritsFrom(TH2::Class())) {gPad->SetUniqueID(0); return;}
45 TH2 *h = (TH2*)select;
46 gPad->GetCanvas()->FeedbackMode(kTRUE);
48 //erase old position and draw a line at current position
49 int pyold = gPad->GetUniqueID();
50 int px = gPad->GetEventX();
51 int py = gPad->GetEventY();
52 float uxmin = gPad->GetUxmin();
53 float uxmax = gPad->GetUxmax();
54 int pxmin = gPad->XtoAbsPixel(uxmin);
55 int pxmax = gPad->XtoAbsPixel(uxmax);
56 if(pyold) gVirtualX->DrawLine(pxmin,pyold,pxmax,pyold);
57 gVirtualX->DrawLine(pxmin,py,pxmax,py);
58 gPad->SetUniqueID(py);
59 Float_t upy = gPad->AbsPixeltoY(py);
60 Float_t y = gPad->PadtoY(upy);
62 //create or set the new canvas c2
63 TVirtualPad *padsav = gPad;
64 TCanvas *c2 = (TCanvas*)gROOT->GetListOfCanvases()->FindObject("c2");
65 if(c2) delete c2->GetPrimitive("Projection");
66 else c2 = new TCanvas("c2","Projection Canvas",710,10,700,500);
67 c2->SetGrid();
68 c2->cd();
70 //draw slice corresponding to mouse position
71 Int_t biny = h->GetYaxis()->FindBin(y);
72 TH1D *hp = h->ProjectionX("",biny,biny);
73 hp->SetFillColor(38);
74 char title[80];
75 sprintf(title,"Projection of biny=%d",biny);
76 hp->SetName("Projection");
77 hp->SetTitle(title);
78 hp->Fit("gaus","ql");
79 hp->GetFunction("gaus")->SetLineColor(kRed);
80 hp->GetFunction("gaus")->SetLineWidth(6);
81 c2->Update();
82 padsav->cd();
#define h(i)
Definition: RSha256.hxx:106
int Int_t
Definition: RtypesCore.h:45
float Float_t
Definition: RtypesCore.h:57
double Double_t
Definition: RtypesCore.h:59
const Bool_t kTRUE
Definition: RtypesCore.h:100
@ kRed
Definition: Rtypes.h:66
#define gROOT
Definition: TROOT.h:404
R__EXTERN TRandom * gRandom
Definition: TRandom.h:62
#define gPad
Definition: TVirtualPad.h:288
#define gVirtualX
Definition: TVirtualX.h:338
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
virtual void SetLineWidth(Width_t lwidth)
Set the line width.
Definition: TAttLine.h:43
virtual void SetLineColor(Color_t lcolor)
Set the line color.
Definition: TAttLine.h:40
The Canvas class.
Definition: TCanvas.h:23
1-D histogram with a double per channel (see TH1 documentation)}
Definition: TH1.h:617
void SetTitle(const char *title) override
See GetStatOverflows for more information.
Definition: TH1.cxx:6708
virtual TFitResultPtr Fit(const char *formula, Option_t *option="", Option_t *goption="", Double_t xmin=0, Double_t xmax=0)
Fit histogram with function fname.
Definition: TH1.cxx:3904
void Draw(Option_t *option="") override
Draw this histogram with options.
Definition: TH1.cxx:3070
virtual TF1 * GetFunction(const char *name) const
Return pointer to function with name.
Definition: TH1.cxx:8926
void SetName(const char *name) override
Change the name of this histogram.
Definition: TH1.cxx:8835
virtual void SetStats(Bool_t stats=kTRUE)
Set statistics option on/off.
Definition: TH1.cxx:8865
2-D histogram with a float per channel (see TH1 documentation)}
Definition: TH2.h:257
Service class for 2-D histogram classes.
Definition: TH2.h:30
Int_t Fill(Double_t) override
Invalid Fill method.
Definition: TH2.cxx:358
static TClass * Class()
Mother of all ROOT objects.
Definition: TObject.h:37
virtual Bool_t InheritsFrom(const char *classname) const
Returns kTRUE if object inherits from class "classname".
Definition: TObject.cxx:445
virtual void Rannor(Float_t &a, Float_t &b)
Return 2 numbers distributed following a gaussian with mean=0 and sigma=1.
Definition: TRandom.cxx:500
TVirtualPad is an abstract base class for the Pad and Canvas classes.
Definition: TVirtualPad.h:51
virtual TVirtualPad * cd(Int_t subpadnumber=0)=0
Double_t y[n]
Definition: legend1.C:17
return c1
Definition: legend1.C:41
return c2
Definition: legend2.C:14