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grad.C
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1 /// \file
2 /// \ingroup tutorial_cocoa
3 /// This macro shows how to create and use linear gradients to fill
4 /// a histogram or a pad.
5 /// Requires OS X and ROOT configured with --enable-cocoa.
6 ///
7 /// \macro_code
8 ///
9 /// \author Timur Pocheptsov
10 
11 //Includes for ACLiC (cling does not need them).
12 #include "TColorGradient.h"
13 #include "TVirtualX.h"
14 #include "TCanvas.h"
15 #include "TColor.h"
16 #include "TError.h"
17 #include "TH1F.h"
18 
19 //Aux. functions for tutorials/cocoa.
20 #include "customcolor.h"
21 
22 void grad()
23 {
24  //1. Try to 'allocate' five indices for our custom colors.
25  //We can use hard-coded indices like 1001, 1002, 1003, ... but
26  //I prefer to find free indices in the ROOT's color table
27  //to avoid possible conflicts with other tutorials.
28  Color_t colorIndices[5] = {};
29  if (ROOT::CocoaTutorials::FindFreeCustomColorIndices(colorIndices) != 5) {
30  ::Error("grad", "failed to create new custom colors");
31  return;
32  }
33 
34  //2. Test if we have the right GUI back-end:
35  TCanvas * const cnv = new TCanvas("gradient demo 1", "gradient demo 1", 100, 100, 600, 600);
36  //After canvas was created, gVirtualX should be non-null.
37  if (gVirtualX && !gVirtualX->InheritsFrom("TGCocoa")) {
38  ::Error("grad", "This macro works only on MacOS X with --enable-cocoa");
39  delete cnv;
40  return;
41  }
42 
43  typedef TColorGradient::Point Point;
44 
45  //3. Create custom colors.
46  //Linear gradient is defined by: 1) colors (to interpolate between them),
47  //2) coordinates for these colors along the gradient axis [0., 1.].
48  //3) Start and end points for a gradient, you specify them in some NDC rect ([0,0 - 1,1]),
49  //and this rect is either: bounding rect of your polygon/object to fill
50  //(gradient->SetCoordinateMode(TColorGradient::kObjectBoundingMode))
51  //or bounding rect of a pad (gradient->SetCoordinateMode(TColorGradient::kPadMode)).
52  //kObjectBoundingMode is the default one.
53 
54  const Color_t &frameGradient = colorIndices[2];//This gradient is a mixture of colorIndices[0] and colorIndices[1]
55  //Fill color for a pad frame:
56  {
57  new TColor(colorIndices[0], 0.25, 0.25, 0.25, "special pad color1", 0.55);
58  new TColor(colorIndices[1], 1., 1., 1., "special pad color2", 0.05);
59 
60  const Double_t locations[] = {0., 0.2, 0.8, 1.};
61  const Color_t gradientIndices[4] = {colorIndices[0], colorIndices[1], colorIndices[1], colorIndices[0]};
62 
63  //Gradient for a pad's frame.
64  TLinearGradient * const gradFill1 = new TLinearGradient(frameGradient, 4, locations, gradientIndices);
65  //Horizontal:
66  gradFill1->SetStartEnd(Point(0., 0.), Point(1., 0.));
67  }
68 
69  //This gradient is a mixture of two standard colors:
70  const Color_t &padGradient = colorIndices[3];
71  //Fill color for a pad:
72  {
73  const Double_t locations[] = {0., 1.};
74  const Color_t gradientIndices[2] = {30, 38};//We create a gradient from system colors.
75 
76  //Gradient for a pad.
77  TLinearGradient * const gradFill2 = new TLinearGradient(padGradient, 2, locations, gradientIndices);
78  //Vertical:
79  gradFill2->SetStartEnd(Point(0., 0.), Point(0., 1.));
80  }
81 
82  //Another gradient from three standard colors:
83  const Color_t &histGradient = colorIndices[4];
84  //Fill color for a histogram:
85  {
86  const Color_t gradientIndices[3] = {kYellow, kOrange, kRed};
87  const Double_t locations[3] = {0., 0.5, 1.};
88 
89  //Gradient for a histogram.
90  TLinearGradient * const gradFill3 = new TLinearGradient(histGradient, 3, locations, gradientIndices);
91  //Vertical:
92  gradFill3->SetStartEnd(Point(0., 0.), Point(0., 1.));
93  }
94 
95  cnv->SetFillColor(padGradient);
96  cnv->SetFrameFillColor(frameGradient);
97 
98  TH1F * const hist = new TH1F("a1", "b1", 20, -3., 3.);
99  hist->SetFillColor(histGradient);
100  hist->FillRandom("gaus", 100000);
101  hist->Draw();
102 }
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
TAttPad::SetFrameFillColor
void SetFrameFillColor(Color_t color=1)
Definition: TAttPad.h:79
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
kRed
@ kRed
Definition: Rtypes.h:66
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
kYellow
@ kYellow
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