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Reference Guide
polytest1.C
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1 /// \file
2 /// \ingroup tutorial_graphics
3 /// \notebook
4 /// This macro is testing the "compacting" algorithm in TPadPainter.
5 /// It reduces the number of polygon's vertices using actual pixel coordinates.
6 ///
7 /// \macro_image
8 ///
9 /// It's not really useful, but just to test that the resulting polygon
10 /// is still reasonable. Initial number of points is 1000000, after "compression"
11 /// it's 523904 (with default canvas size, before you tried to resize it) - so almost half of
12 /// vertices were removed but you can still see the reasonable shape. If you resize
13 /// a canvas to a smaller size, the number of vertices after compression can be something like 5000 and even less.
14 /// It's easy to 'fool' this algorithm though in this particular case (ellipse is a kind of fringe case,
15 /// you can easily have a sequence of almost unique vertices (at a pixel level).
16 ///
17 /// \macro_code
18 ///
19 /// \author Timur Pocheptsov
20 
21 //Includes for ACLiC.
22 #include <cassert>
23 #include <vector>
24 
25 #include "TRandom.h"
26 #include "TCanvas.h"
27 #include "TError.h"
28 #include "Rtypes.h"
29 #include "TNamed.h"
30 #include "TMath.h"
31 
32 class PolyTest1 : public TNamed, public TAttLine, public TAttFill {
33 public:
34  PolyTest1(unsigned nVertices);
35 
36  void Paint(const Option_t *notUsed);
37  void Reset(unsigned nVertices);
38 
39 private:
40  enum {
41  kNPointsDefault = 10000//minimal number of points.
42  };
43 
44  std::vector<Double_t> fXs;
45  std::vector<Double_t> fYs;
46 };
47 
48 //_____________________________________________________________
49 PolyTest1::PolyTest1(unsigned nVertices)
50  : TNamed("polygon_compression_test1", "polygon_compression_test1")
51 {
52  Reset(nVertices);
53 }
54 
55 //_____________________________________________________________
56 void PolyTest1::Reset(unsigned nVertices)
57 {
58  //Some canvas must already exist by this point.
59  assert(gPad != 0 && "Reset, gPad is null");
60  //We need a gRandom to exist.
61  assert(gRandom != 0 && "Reset, gRandom is null");
62 
63  if (nVertices < kNPointsDefault) {
64  Warning("Reset", "resetting nVertices parameter to %u", unsigned(kNPointsDefault));
65  nVertices = kNPointsDefault;
66  }
67 
68  fXs.resize(nVertices);
69  fYs.resize(nVertices);
70 
71  Double_t xMin = 0., xMax = 0., yMin = 0., yMax = 0.;
72  gPad->GetRange(xMin, yMin, xMax, yMax);
73  assert(xMax - xMin > 0 && yMax - yMin > 0 && "Reset, invalid canvas' ranges");
74 
75  const Double_t xCentre = xMin + 0.5 * (xMax - xMin);
76  const Double_t yCentre = yMin + 0.5 * (yMax - yMin);
77 
78  const Double_t r = TMath::Min(xMax - xMin, yMax - yMin) * 0.8 / 2;
79  const Double_t angle = TMath::TwoPi() / (nVertices - 1);
80 
81  for (unsigned i = 0; i < nVertices - 1; ++i) {
82  const Double_t currR = r + gRandom->Rndm() * r * 0.01;
83  fXs[i] = xCentre + currR * TMath::Cos(angle * i);
84  fYs[i] = yCentre + currR * TMath::Sin(angle * i);
85  }
86 
87  fXs[nVertices - 1] = fXs[0];
88  fYs[nVertices - 1] = fYs[0];
89 }
90 
91 //_____________________________________________________________
92 void PolyTest1::Paint(const Option_t * /*notUsed*/)
93 {
94  assert(gPad != 0 && "Paint, gPad is null");
95 
97  gPad->PaintFillArea((Int_t)fXs.size(), &fXs[0], &fYs[0]);
98 
100  gPad->PaintPolyLine((Int_t)fXs.size(), &fXs[0], &fYs[0]);
101 }
102 
103 void polytest1()
104 {
105  TCanvas * const cnv = new TCanvas;
106  cnv->cd();
107 
108  PolyTest1 * polygon = new PolyTest1(1000000);
109  polygon->SetLineColor(kBlue);
110  polygon->SetFillColor(kRed);
111  polygon->SetLineWidth(1);
112  polygon->Draw();//Attach a polygon to a canvas.
113 }
const char Option_t
Definition: RtypesCore.h:62
Definition: Rtypes.h:61
TVirtualPad * cd(Int_t subpadnumber=0)
Set current canvas & pad.
Definition: TCanvas.cxx:659
Short_t Min(Short_t a, Short_t b)
Definition: TMathBase.h:170
int Int_t
Definition: RtypesCore.h:41
virtual void Modify()
Change current line attributes if necessary.
Definition: TAttLine.cxx:232
Fill Area Attributes class.
Definition: TAttFill.h:24
The TNamed class is the base class for all named ROOT classes.
Definition: TNamed.h:33
virtual void Modify()
Change current fill area attributes if necessary.
Definition: TAttFill.cxx:209
Double_t TwoPi()
Definition: TMath.h:45
virtual Double_t Rndm()
Machine independent random number generator.
Definition: TRandom.cxx:512
TRandom2 r(17)
void Reset(Detail::TBranchProxy *x)
void Warning(const char *location, const char *msgfmt,...)
R__EXTERN TRandom * gRandom
Definition: TRandom.h:66
Double_t Cos(Double_t)
Definition: TMath.h:424
The Canvas class.
Definition: TCanvas.h:41
virtual void Paint(Option_t *option="")
This method must be overridden if a class wants to paint itself.
Definition: TObject.cxx:564
double Double_t
Definition: RtypesCore.h:55
Double_t Sin(Double_t)
Definition: TMath.h:421
#define gPad
Definition: TVirtualPad.h:289
Definition: Rtypes.h:61
Line Attributes class.
Definition: TAttLine.h:24