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1/// \file
2/// \ingroup tutorial_graphics
3/// \notebook
4/// Generate small triangles randomly in the canvas.
5/// Each triangle has a unique id and a random color in the color palette
7/// ~~~{.cpp}
8/// root > .x triangles.C
9/// ~~~
11/// Then click on any triangle. A message showing the triangle number
12/// and its color will be printed.
14/// \macro_image
15/// \macro_code
17/// \author Rene Brun
19void triangles(Int_t ntriangles=50) {
20 TCanvas *c1 = new TCanvas("c1","triangles",10,10,700,700);
21 TRandom r;
22 Double_t dx = 0.2; Double_t dy = 0.2;
23 Int_t ncolors = gStyle->GetNumberOfColors();
24 Double_t x[4],y[4];
25 TColor *c;
26 Int_t ci;
27 for (Int_t i=0;i<ntriangles;i++) {
28 x[0] = r.Uniform(.05,.95); y[0] = r.Uniform(.05,.95);
29 x[1] = x[0] + dx*r.Rndm(); y[1] = y[0] + dy*r.Rndm();
30 x[2] = x[1] - dx*r.Rndm(); y[2] = y[1] - dy*r.Rndm();
31 x[3] = x[0]; y[3] = y[0];
32 TPolyLine *pl = new TPolyLine(4,x,y);
33 pl->SetUniqueID(i);
34 ci = ncolors*r.Rndm();
35 c = gROOT->GetColor(TColor::GetColorPalette(ci));
36 c->SetAlpha(r.Rndm());
37 pl->SetFillColor(ci);
38 pl->Draw("f");
39 }
40 c1->AddExec("ex","TriangleClicked()");
43void TriangleClicked() {
44 //this action function is called whenever you move the mouse
45 //it just prints the id of the picked triangle
46 //you can add graphics actions instead
47 int event = gPad->GetEvent();
48 if (event != 11) return; //may be comment this line
49 TObject *select = gPad->GetSelected();
50 if (!select) return;
51 if (select->InheritsFrom(TPolyLine::Class())) {
52 TPolyLine *pl = (TPolyLine*)select;
53 printf("You have clicked triangle %d, color=%d\n",
54 pl->GetUniqueID(),pl->GetFillColor());
55 }
int Int_t
Definition: CPyCppyy.h:43
void Class()
Definition: Class.C:29
ROOT::R::TRInterface & r
Definition: Object.C:4
#define c(i)
Definition: RSha256.hxx:101
double Double_t
Definition: RtypesCore.h:59
#define gROOT
Definition: TROOT.h:404
R__EXTERN TStyle * gStyle
Definition: TStyle.h:412
#define gPad
Definition: TVirtualPad.h:287
virtual Color_t GetFillColor() const
Return the fill area color.
Definition: TAttFill.h:30
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
The Canvas class.
Definition: TCanvas.h:23
The color creation and management class.
Definition: TColor.h:19
static Int_t GetColorPalette(Int_t i)
Static function returning the color number i in current palette.
Definition: TColor.cxx:1402
Mother of all ROOT objects.
Definition: TObject.h:37
virtual UInt_t GetUniqueID() const
Return the unique object id.
Definition: TObject.cxx:377
virtual Bool_t InheritsFrom(const char *classname) const
Returns kTRUE if object inherits from class "classname".
Definition: TObject.cxx:445
virtual void SetUniqueID(UInt_t uid)
Set the unique object id.
Definition: TObject.cxx:707
Defined by an array on N points in a 2-D space.
Definition: TPolyLine.h:23
virtual void Draw(Option_t *option="")
Draw this polyline with its current attributes.
Definition: TPolyLine.cxx:228
This is the base class for the ROOT Random number generators.
Definition: TRandom.h:27
Int_t GetNumberOfColors() const
Return number of colors in the color palette.
Definition: TStyle.cxx:1122
return c1
Definition: legend1.C:41
Double_t y[n]
Definition: legend1.C:17
Double_t x[n]
Definition: legend1.C:17