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grad2.C
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1 /// \file
2 /// \ingroup tutorial_cocoa
3 /// Gradient fill with transparency and "SAME" option.
4 /// Requires OS X and ROOT configured with --enable-cocoa.
5 ///
6 /// \macro_code
7 ///
8 /// \author Timur Pocheptsov
9 
10 //Includes for ACLiC (cling does not need them).
11 #include "TColorGradient.h"
12 #include "TVirtualX.h"
13 #include "TCanvas.h"
14 #include "TError.h"
15 #include "TColor.h"
16 #include "TH1F.h"
17 
18 //Aux. functions for tutorials/cocoa.
19 #include "customcolor.h"
20 
21 void grad2()
22 {
23  //1. 'Allocate' four indices for our custom colors.
24  //We can use hard-coded indices like 1001, 1002, 1003 ... but
25  //I prefer to find free indices in the ROOT's color table
26  //to avoid possible conflicts with other tutorials.
27  Color_t freeIndices[4] = {};
29  ::Error("grad2", "can not allocate new custom colors");
30  return;
31  }
32 
33  //'Aliases' (instead of freeIndices[someIndex])
34  const Color_t customRed = freeIndices[0], grad1 = freeIndices[1];
35  const Color_t customGreen = freeIndices[2], grad2 = freeIndices[3];
36 
37  //2. Check that we are ROOT with Cocoa back-end enabled.
38  TCanvas * const cnv = new TCanvas("gradient demo 2", "gradient demo 2", 100, 100, 800, 600);
39  //After canvas was created, gVirtualX should be non-null.
40  if (gVirtualX && !gVirtualX->InheritsFrom("TGCocoa")) {
41  ::Error("grad2", "This macro works only on OS X with --enable-cocoa");
42  delete cnv;
43  return;
44  }
45 
46  //3. Custom colors:
47  // a) Custom semi-transparent red.
48  new TColor(customRed, 1., 0., 0., "red", 0.5);
49 
50 
51  // b) Gradient (from our semi-transparent red to ROOT's kOrange).
52  // Linear gradient is defined by: 1) colors (to interpolate between them),
53  // 2) coordinates for these colors along the gradient axis [0., 1.] (must be sorted!).
54  // 3) Start and end points for a gradient, you specify them in some NDC rect ([0,0 - 1,1]),
55  // and this rect is either: bounding rect of your polygon/object to fill
56  // (gradient->SetCoordinateMode(TColorGradient::kObjectBoundingMode))
57  // or bounding rect of a pad (gradient->SetCoordinateMode(TColorGradient::kPadMode)).
58  // kObjectBoundingMode is the default one.
59  const Double_t locations[] = {0., 1.};
60  const Color_t idx1[] = {customRed, kOrange};
61  TLinearGradient * const gradFill1 = new TLinearGradient(grad1, 2, locations, idx1);
62 
63  typedef TColorGradient::Point Point;
64  //Starting and ending points for a gradient fill (it's a vertical gradient):
65  gradFill1->SetStartEnd(Point(0., 0.), Point(0., 1.));
66 
67  // c) Custom semi-transparent green.
68  new TColor(customGreen, 0., 1., 0., "green", 0.5);
69 
70  // d) Gradient from ROOT's kBlue to our custom green.
71  const Color_t idx2[] = {customGreen, kBlue};
72 
73  TLinearGradient * const gradFill2 = new TLinearGradient(grad2, 2, locations, idx2);
74  //Vertical gradient fill.
75  gradFill2->SetStartEnd(Point(0., 0), Point(0., 1.));
76 
77  TH1F * const hist = new TH1F("a2", "b2", 10, -2., 3.);
78  TH1F * const hist2 = new TH1F("c3", "d3", 10, -3., 3.);
79  hist->FillRandom("landau", 100000);
80  hist2->FillRandom("gaus", 100000);
81 
82  hist->SetFillColor(grad1);
83  hist2->SetFillColor(grad2);
84 
85  hist2->Draw();
86  hist->Draw("SAME");
87 }
TH1F.h
gVirtualX
#define gVirtualX
Definition: TVirtualX.h:338
TColorGradient.h
kOrange
@ kOrange
Definition: Rtypes.h:67
TColor.h
TVirtualX.h
TColorGradient::Point
Definition: TColorGradient.h:55
TCanvas.h
ROOT::CocoaTutorials::FindFreeCustomColorIndices
unsigned FindFreeCustomColorIndices(Color_t(&indices)[N])
Definition: customcolor.h:38
Color_t
short Color_t
Definition: RtypesCore.h:83
TColor
Definition: TColor.h:19
customcolor.h
TLinearGradient
Definition: TColorGradient.h:99
TH1::FillRandom
virtual void FillRandom(const char *fname, Int_t ntimes=5000)
Fill histogram following distribution in function fname.
Definition: TH1.cxx:3444
TLinearGradient::SetStartEnd
void SetStartEnd(const Point &p1, const Point &p2)
Set end and start.
Definition: TColorGradient.cxx:218
Double_t
double Double_t
Definition: RtypesCore.h:59
TCanvas
Definition: TCanvas.h:23
TH1F
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:572
kBlue
@ kBlue
Definition: Rtypes.h:66
TH1::Draw
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition: TH1.cxx:2997
Error
void Error(const char *location, const char *msgfmt,...)
Use this function in case an error occurred.
Definition: TError.cxx:187
TError.h