TColor Class Reference

The color creation and management class.

• Introduction
• Basic colors
• The color wheel
• Bright and dark colors
• Accessible Color Schemes
• Gray scale view of of canvas with colors
• Color palettes
• High quality predefined palettes
  • Colour Vision Deficiency (CVD) friendly palettes
  • Non Colour Vision Deficiency (CVD) friendly palettes
• Palette inversion
• Color transparency

Introduction

Colors are defined by their red, green and blue components, simply called the RGB components. The colors are also known by the hue, light and saturation components also known as the HLS components. When a new color is created the components of both color systems are computed.

At initialization time, a table of colors is generated. An existing color can be retrieved by its index:

TColor *color = gROOT->GetColor(10);

Then it can be manipulated. For example its RGB components can be modified:

color->SetRGB(0.1, 0.2, 0.3);

A new color can be created the following way:

Int_t ci = 1756; // color index
auto color = new TColor(ci, 0.1, 0.2, 0.3);

Since

6.07/07: TColor::GetFreeColorIndex() allows to make sure the new color is created with an unused color index:

Int_t ci = TColor::GetFreeColorIndex();
auto color = new TColor(ci, 0.1, 0.2, 0.3);

Two sets of colors are initialized;

• The basic colors: colors with index from 0 to 50.
• The color wheel: colors with indices from 300 to 1000.

Basic colors

The following image displays the 50 basic colors.

{
   auto c = new TCanvas("c","Fill Area colors",0,0,500,200);
   c->DrawColorTable();
   return c;
}

The color wheel

The wheel contains the recommended 216 colors to be used in web applications.

The colors in the color wheel are created by TColor::CreateColorWheel.

Using this color set for your text, background or graphics will give your application a consistent appearance across different platforms and browsers.

Colors are grouped by hue, the aspect most important in human perception. Touching color chips have the same hue, but with different brightness and vividness.

Colors of slightly different hues clash. If you intend to display colors of the same hue together, you should pick them from the same group.

Each color chip is identified by a mnemonic (e.g. kYellow) and a number. The keywords, kRed, kBlue, kYellow, kPink, etc are defined in the header file Rtypes.h that is included in all ROOT other header files. It is better to use these keywords in user code instead of hardcoded color numbers, e.g.:

myObject.SetFillColor(kRed);
myObject.SetFillColor(kYellow-10);
myLine.SetLineColor(kMagenta+2);

{
   auto w  = new TColorWheel();
   auto cw = new TCanvas("cw","cw",0,0,400,400);
   w->SetCanvas(cw);
   w->Draw();
}

The complete list of predefined color names is the following:

kWhite  = 0,   kBlack  = 1,   kGray    = 920,  kRed    = 632,  kGreen  = 416,
kBlue   = 600, kYellow = 400, kMagenta = 616,  kCyan   = 432,  kOrange = 800,
kSpring = 820, kTeal   = 840, kAzure   =  860, kViolet = 880,  kPink   = 900

Note the special role of color kWhite (color number 0). It is the default background color also. For instance in a PDF or PS files (as paper is usually white) it is simply not painted. To have a white color behaving like the other color the simplest is to define an other white color not attached to the color index 0:

Int_t ci = TColor::GetFreeColorIndex();
TColor *color = new TColor(ci, 1., 1., 1.);

Bright and dark colors

Dark and bright colors are used to add 3D effects to graphical objects like TWbox, TPave, TPaveText, TPaveLabel, etc. and in colored lego plots.

Two static functions are available that return the bright or dark color number corresponding to a given color index. If these variants don't already exist, they are created as needed:

Int_t dark   = TColor::GetColorDark(color_index);
Int_t bright = TColor::GetColorBright(color_index);

Accessible Color Schemes

Choosing an appropriate color scheme is essential for making results easy to understand and interpret. Factors like colorblindness and converting colors to grayscale for publications can impact accessibility. Furthermore, results should be aesthetically pleasing. The following three color schemes, recommended by M. Petroff in arXiv:2107.02270v2 and available on GitHub under the MIT License, meet these criteria.

These three color schemes are available as color sets with 6, 8, and 10 colors, named kP[6, 8, 10]ColorName. For example, kP6Red represents the red color within the P6 color scheme (P for Petroff or Preferred).

The example thstackcolorscheme.C illustrates how to use these color schemes in THStack drawings. It also demonstrates that they are effective in grayscale.

Grayscale view of of canvas with colors

One can toggle between a grayscale preview and the regular colored mode using TCanvas::SetGrayscale(). Note that in grayscale mode, access via RGB will return grayscale values according to ITU standards (and close to b&w printer gray-scales), while access via HLS returns de-saturated gray-scales. The image below shows the ROOT color wheel in grayscale mode.

{
   auto w  = new TColorWheel();
   auto cw = new TCanvas("cw","cw",0,0,400,400);
   cw->GetCanvas()->SetGrayscale();
   w->SetCanvas(cw);
   w->Draw();
}

Color palettes

It is often very useful to represent a variable with a color map. The concept of "color palette" allows to do that. One color palette is active at any time. This "current palette" is set using:

gStyle->SetPalette(...);

This function has two parameters: the number of colors in the palette and an array of containing the indices of colors in the palette. The following small example demonstrates how to define and use the color palette:

{
   auto c1 = new TCanvas("c1","c1",0,0,600,400);
   TF2 *f1 = new TF2("f1","0.1+(1-(x-2)*(x-2))*(1-(y-2)*(y-2))",1,3,1,3);
   Int_t palette[5];
   palette[0] = 15;
   palette[1] = 20;
   palette[2] = 23;
   palette[3] = 30;
   palette[4] = 32;
   gStyle->SetPalette(5,palette);
   f1->Draw("colz");
   return c1;
}

To define more a complex palette with a continuous gradient of color, one should use the static function TColor::CreateGradientColorTable(). The following example demonstrates how to proceed:

{
   auto c2 = new TCanvas("c2","c2",0,0,600,400);
   auto f2 = new TF2("f2","0.1+(1-(x-2)*(x-2))*(1-(y-2)*(y-2))",1,3,1,3);
   const Int_t Number = 3;
   Double_t Red[Number]    = { 1.00, 0.00, 0.00};
   Double_t Green[Number]  = { 0.00, 1.00, 0.00};
   Double_t Blue[Number]   = { 1.00, 0.00, 1.00};
   Double_t Length[Number] = { 0.00, 0.50, 1.00 };
   Int_t nb=50;
   TColor::CreateGradientColorTable(Number,Length,Red,Green,Blue,nb);
   f2->SetContour(nb);
   f2->SetLineWidth(1);
   f2->SetLineColor(kBlack);
   f2->Draw("surf1z");
   return c2;
}

The function TColor::CreateGradientColorTable() automatically calls gStyle->SetPalette(), so there is not need to add one.

After a call to TColor::CreateGradientColorTable() it is sometimes useful to store the newly create palette for further use. In particular, it is recommended to do if one wants to switch between several user define palettes. To store a palette in an array it is enough to do:

Int_t MyPalette[100];
Double_t Red[]    = {0., 0.0, 1.0, 1.0, 1.0};
Double_t Green[]  = {0., 0.0, 0.0, 1.0, 1.0};
Double_t Blue[]   = {0., 1.0, 0.0, 0.0, 1.0};
Double_t Length[] = {0., .25, .50, .75, 1.0};
Int_t FI = TColor::CreateGradientColorTable(5, Length, Red, Green, Blue, 100);
for (int i=0;i<100;i++) MyPalette[i] = FI+i;

Later on to reuse the palette MyPalette it will be enough to do

gStyle->SetPalette(100, MyPalette);

As only one palette is active, one need to use TExec to be able to display plots using different palettes on the same pad. The tutorial multipalette.C illustrates this feature.

 
#include "TStyle.h"
#include "TColor.h"
#include "TF2.h"
#include "TExec.h"
#include "TCanvas.h"
 
void Pal1()
{
   static Int_t  colors[50];
   static Bool_t initialized = kFALSE;
 
   Double_t Red[3]    = { 1.00, 0.00, 0.00};
   Double_t Green[3]  = { 0.00, 1.00, 0.00};
   Double_t Blue[3]   = { 1.00, 0.00, 1.00};
   Double_t Length[3] = { 0.00, 0.50, 1.00 };
 
   if(!initialized){
      Int_t FI = TColor::CreateGradientColorTable(3,Length,Red,Green,Blue,50);
      for (int i=0; i<50; i++) colors[i] = FI+i;
      initialized = kTRUE;
      return;
   }
   gStyle->SetPalette(50,colors);
}
 
void Pal2()
{
   static Int_t  colors[50];
   static Bool_t initialized = kFALSE;
 
   Double_t Red[3]    = { 1.00, 0.50, 0.00};
   Double_t Green[3]  = { 0.50, 0.00, 1.00};
   Double_t Blue[3]   = { 1.00, 0.00, 0.50};
   Double_t Length[3] = { 0.00, 0.50, 1.00 };
 
   if(!initialized){
      Int_t FI = TColor::CreateGradientColorTable(3,Length,Red,Green,Blue,50);
      for (int i=0; i<50; i++) colors[i] = FI+i;
      initialized = kTRUE;
      return;
   }
   gStyle->SetPalette(50,colors);
}
 
void multipalette() {
   TCanvas *c3  = new TCanvas("c3","C3",0,0,600,400);
   c3->Divide(2,1);
   TF2 *f3 = new TF2("f3","0.1+(1-(x-2)*(x-2))*(1-(y-2)*(y-2))",1,3,1,3);
   f3->SetLineWidth(1);
   f3->SetLineColor(kBlack);
 
   c3->cd(1);
   f3->Draw("surf1");
   TExec *ex1 = new TExec("ex1","Pal1();");
   ex1->Draw();
   f3->Draw("surf1 same");
 
   c3->cd(2);
   f3->Draw("surf1");
   TExec *ex2 = new TExec("ex2","Pal2();");
   ex2->Draw();
   f3->Draw("surf1 same");
}

Since

6.26: The function TColor::CreateColorTableFromFile("filename.txt") allows you to create a color palette based on an input ASCII file. In contrast to TColor::CreateGradientColorTable(), here the length (spacing) is constant and can not be tuned. There is no gradient being interpolated between adjacent colors. The palette will contain the exact colors stored in the file, that comprises one line per color in the format "r g b" as floats.

High quality predefined palettes

Since

6.04: 63 high quality palettes are predefined with 255 colors each.

These palettes can be accessed "by name" with gStyle->SetPalette(num). num can be taken within the following enum:

kDeepSea=51,          kGreyScale=52,    kDarkBodyRadiator=53,
kBlueYellow= 54,      kRainBow=55,      kInvertedDarkBodyRadiator=56,
kBird=57,             kCubehelix=58,    kGreenRedViolet=59,
kBlueRedYellow=60,    kOcean=61,        kColorPrintableOnGrey=62,
kAlpine=63,           kAquamarine=64,   kArmy=65,
kAtlantic=66,         kAurora=67,       kAvocado=68,
kBeach=69,            kBlackBody=70,    kBlueGreenYellow=71,
kBrownCyan=72,        kCMYK=73,         kCandy=74,
kCherry=75,           kCoffee=76,       kDarkRainBow=77,
kDarkTerrain=78,      kFall=79,         kFruitPunch=80,
kFuchsia=81,          kGreyYellow=82,   kGreenBrownTerrain=83,
kGreenPink=84,        kIsland=85,       kLake=86,
kLightTemperature=87, kLightTerrain=88, kMint=89,
kNeon=90,             kPastel=91,       kPearl=92,
kPigeon=93,           kPlum=94,         kRedBlue=95,
kRose=96,             kRust=97,         kSandyTerrain=98,
kSienna=99,           kSolar=100,       kSouthWest=101,
kStarryNight=102,     kSunset=103,      kTemperatureMap=104,
kThermometer=105,     kValentine=106,   kVisibleSpectrum=107,
kWaterMelon=108,      kCool=109,        kCopper=110,
kGistEarth=111,       kViridis=112,     kCividis=113

As explained in Crameri, F., Shephard, G.E. & Heron, P.J. The misuse of colour in science communication. Nat Commun 11, 5444 (2020) some color maps can visually distord data, specially for people with colour-vision deficiencies.

For instance one can immediately see the disadvantages of the Rainbow color map, which is misleading for colour-blinded people in a 2D plot (not so much in a 3D surfaces).

The kCMYK palette, is also not great because it's dark, then lighter, then half-dark again. Some others, like kAquamarine, have almost no contrast therefore it would be almost impossible (for a color blind person) to see something with a such palette.

Therefore the palettes are classified in two categories: those which are Colour Vision Deficiency friendly and those which are not.

An easy way to classify the palettes is to turn them into grayscale using TCanvas::SetGrayscale(). The grayscale version of a palette should be as proportional as possible, and monotonously increasing or decreasing.

Unless it is symmetrical, then it is fine to have white in the borders and black in the centre (for example an axis that goes between -40 degrees and +40 degrees, the 0 has a meaning in the perceptualcolormap.C example).

A full set of colour-vision deficiency friendly and perceptually uniform colour maps can be downloaded and used with ROOT (since 6.26) via: gStyle->SetPalette("filename.txt") or TColor::CreateColorTableFromFile("filename.txt"). Remember to increase the number of contours for a smoother result, e.g.: gStyle->SetNumberContours(99) if you are drawing with "surf1z" or gStyle->SetNumberContours(256) if with "colz".

Colour Vision Deficiency (CVD) friendly palettes

Non Colour Vision Deficiency (CVD) friendly palettes

Palette inversion

Once a palette is defined, it is possible to invert the color order thanks to the method TColor::InvertPalette. The top of the palette becomes the bottom and vice versa.

{
   auto c  = new TCanvas("c","c",0,0,600,400);
   auto f2 = new TF2("f2","0.1+(1-(x-2)*(x-2))*(1-(y-2)*(y-2))",0.999,3.002,0.999,3.002);
   f2->SetContour(99); gStyle->SetPalette(kCherry);
   TColor::InvertPalette();
   f2->Draw("surf2Z"); f2->SetTitle("kCherry inverted");
}

Color transparency

To make a graphics object transparent it is enough to set its color to a transparent one. The color transparency is defined via its alpha component. The alpha value varies from 0. (fully transparent) to 1. (fully opaque). To set the alpha value of an existing color it is enough to do:

TColor *col26 = gROOT->GetColor(26);
col26->SetAlpha(0.01);

A new color can be created transparent the following way:

Int_t ci = 1756;
auto color = new TColor(ci, 0.1, 0.2, 0.3, "", 0.5); // alpha = 0.5

An example of transparency usage with parallel coordinates can be found in parallelcoordtrans.C.

To ease the creation of a transparent color the static method GetColorTransparent(Int_t color, Float_t a) is provided. In the following example the trans_red color index point to a red color 30% opaque (70% transparent). The alpha value of the color index kRed is not modified.

Int_t trans_red = GetColorTransparent(kRed, 0.3);

This function is also used in the methods SetFillColorAlpha(), SetLineColorAlpha(), SetMarkerColorAlpha() and SetTextColorAlpha(). In the following example the fill color of the histogram histo is set to blue with an opacity of 35% (i.e. a transparency of 65%). (The color kBlue itself is internally stored as fully opaque.)

histo->SetFillColorAlpha(kBlue, 0.35);

The transparency is available on all platforms when the flag OpenGL.CanvasPreferGL is set to 1 in $ROOTSYS/etc/system.rootrc, or on Mac with the Cocoa backend. On the file output it is visible with PDF, PNG, Gif, JPEG, SVG, TeX ... but not PostScript.

Alternatively, you can call at the top of your script gSytle->SetCanvasPreferGL();. Or if you prefer to activate GL for a single canvas c, then use c->SetSupportGL(true);.

The following macro gives an example of transparency usage:

 
void transparency()
{
   auto c1 = new TCanvas("c1", "c1",224,330,700,527);
   c1->Range(-0.125,-0.125,1.125,1.125);
 
   auto tex = new TLatex(0.06303724,0.0194223,"This text is opaque and this line is transparent");
   tex->SetLineWidth(2);
   tex->Draw();
 
   auto arrow = new TArrow(0.5555158,0.07171314,0.8939828,0.6195219,0.05,"|>");
   arrow->SetLineWidth(4);
   arrow->SetAngle(30);
   arrow->Draw();
 
   // Draw a transparent graph.
   Double_t x[10] = {
   0.5232808, 0.8724928, 0.9280086, 0.7059456, 0.7399714,
   0.4659742, 0.8241404, 0.4838825, 0.7936963, 0.743553};
   Double_t y[10] = {
   0.7290837, 0.9631474, 0.4775896, 0.6494024, 0.3555777,
   0.622012, 0.7938247, 0.9482072, 0.3904382, 0.2410359};
   auto graph = new TGraph(10,x,y);
   graph->SetLineColorAlpha(46, 0.1);
   graph->SetLineWidth(7);
   graph->Draw("l");
 
   // Draw an ellipse with opaque colors.
   auto ellipse = new TEllipse(0.1740688,0.8352632,0.1518625,0.1010526,0,360,0);
   ellipse->SetFillColor(30);
   ellipse->SetLineColor(51);
   ellipse->SetLineWidth(3);
   ellipse->Draw();
 
   // Draw an ellipse with transparent colors, above the previous one.
   ellipse = new TEllipse(0.2985315,0.7092105,0.1566977,0.1868421,0,360,0);
   ellipse->SetFillColorAlpha(9, 0.571);
   ellipse->SetLineColorAlpha(8, 0.464);
   ellipse->SetLineWidth(3);
   ellipse->Draw();
 
   // Draw a transparent blue text.
   tex = new TLatex(0.04871059,0.1837649,"This text is transparent");
   tex->SetTextColorAlpha(9, 0.476);
   tex->SetTextSize(0.125);
   tex->SetTextAngle(26.0);
   tex->Draw();
 
   // Draw two transparent markers
   auto marker = new TMarker(0.03080229,0.998008,20);
   marker->SetMarkerColorAlpha(2, .3);
   marker->SetMarkerStyle(20);
   marker->SetMarkerSize(1.7);
   marker->Draw();
   marker = new TMarker(0.1239255,0.8635458,20);
   marker->SetMarkerColorAlpha(2, .2);
   marker->SetMarkerStyle(20);
   marker->SetMarkerSize(1.7);
   marker->Draw();
 
   // Draw an opaque marker
   marker = new TMarker(0.3047994,0.6344622,20);
   marker->SetMarkerColor(2);
   marker->SetMarkerStyle(20);
   marker->SetMarkerSize(1.7);
   marker->Draw();
 
}

Definition at line 21 of file TColor.h.

Public Member Functions
	TColor ()
	Default constructor.
	TColor (const TColor &color)
	Color copy constructor.
	TColor (Float_t r, Float_t g, Float_t b, Float_t a=1)
	Fast TColor constructor.
	TColor (Int_t color, Float_t r, Float_t g, Float_t b, const char *name="", Float_t a=1)
	Normal color constructor.
virtual	~TColor ()
	Color destructor.
const char *	AsHexString () const
	Return color as hexadecimal string.
void	Copy (TObject &color) const override
	Copy this color to obj.
Float_t	GetAlpha () const
Float_t	GetBlue () const
virtual Float_t	GetGrayscale () const
Float_t	GetGreen () const
virtual void	GetHLS (Float_t &h, Float_t &l, Float_t &s) const
Float_t	GetHue () const
Float_t	GetLight () const
Int_t	GetNumber () const
ULong_t	GetPixel () const
	Return pixel value corresponding to this color.
Float_t	GetRed () const
virtual void	GetRGB (Float_t &r, Float_t &g, Float_t &b) const
Float_t	GetSaturation () const
TClass *	IsA () const override
void	ls (Option_t *option="") const override
	List this color with its attributes.
TColor &	operator= (const TColor &color)
void	Print (Option_t *option="") const override
	Dump this color with its attributes.
virtual void	SetAlpha (Float_t a)
void	SetName (const char *name) override
	Set the color name and change also the name of the "dark" and "bright" associated colors if they exist.
virtual void	SetRGB (Float_t r, Float_t g, Float_t b)
	Initialize this color and its "dark" and "bright" associated colors.
void	Streamer (TBuffer &) override
	Stream an object of class TObject.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
Public Member Functions inherited from TNamed
	TNamed ()
	TNamed (const char *name, const char *title)
	TNamed (const TNamed &named)
	TNamed copy ctor.
	TNamed (const TString &name, const TString &title)
virtual	~TNamed ()
	TNamed destructor.
void	Clear (Option_t *option="") override
	Set name and title to empty strings ("").
TObject *	Clone (const char *newname="") const override
	Make a clone of an object using the Streamer facility.
Int_t	Compare (const TObject *obj) const override
	Compare two TNamed objects.
void	Copy (TObject &named) const override
	Copy this to obj.
virtual void	FillBuffer (char *&buffer)
	Encode TNamed into output buffer.
const char *	GetName () const override
	Returns name of object.
const char *	GetTitle () const override
	Returns title of object.
ULong_t	Hash () const override
	Return hash value for this object.
TClass *	IsA () const override
Bool_t	IsSortable () const override
void	ls (Option_t *option="") const override
	List TNamed name and title.
TNamed &	operator= (const TNamed &rhs)
	TNamed assignment operator.
void	Print (Option_t *option="") const override
	Print TNamed name and title.
virtual void	SetNameTitle (const char *name, const char *title)
	Set all the TNamed parameters (name and title).
virtual void	SetTitle (const char *title="")
	Set the title of the TNamed.
virtual Int_t	Sizeof () const
	Return size of the TNamed part of the TObject.
void	Streamer (TBuffer &) override
	Stream an object of class TObject.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
Public Member Functions inherited from TObject
	TObject ()
	TObject constructor.
	TObject (const TObject &object)
	TObject copy ctor.
virtual	~TObject ()
	TObject destructor.
void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract.
virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad.
virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action.
ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.
virtual const char *	ClassName () const
	Returns name of class to which the object belongs.
virtual void	Delete (Option_t *option="")
	Delete this object.
virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object.
virtual void	Draw (Option_t *option="")
	Default Draw method for all objects.
virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.
virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad with: gROOT->SetSelectedPad(c1).
virtual void	Dump () const
	Dump contents of object on stdout.
virtual void	Error (const char *method, const char *msgfmt,...) const
	Issue error message.
virtual void	Execute (const char *method, const char *params, Int_t *error=nullptr)
	Execute method on this object with the given parameter string, e.g.
virtual void	Execute (TMethod *method, TObjArray *params, Int_t *error=nullptr)
	Execute method on this object with parameters stored in the TObjArray.
virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py).
virtual void	Fatal (const char *method, const char *msgfmt,...) const
	Issue fatal error message.
virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes.
virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes.
virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.
virtual const char *	GetIconName () const
	Returns mime type name of object.
virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py).
virtual Option_t *	GetOption () const
virtual UInt_t	GetUniqueID () const
	Return the unique object id.
virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out.
Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.
virtual void	Info (const char *method, const char *msgfmt,...) const
	Issue info message.
virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname".
virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl.
virtual void	Inspect () const
	Dump contents of this object in a graphics canvas.
void	InvertBit (UInt_t f)
Bool_t	IsDestructed () const
	IsDestructed.
virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory).
virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).
R__ALWAYS_INLINE Bool_t	IsOnHeap () const
R__ALWAYS_INLINE Bool_t	IsZombie () const
void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).
virtual Bool_t	Notify ()
	This method must be overridden to handle object notification (the base implementation is no-op).
void	Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete.
void	operator delete (void *ptr)
	Operator delete.
void	operator delete (void *ptr, void *vp)
	Only called by placement new when throwing an exception.
void	operator delete[] (void *ptr)
	Operator delete [].
void	operator delete[] (void *ptr, void *vp)
	Only called by placement new[] when throwing an exception.
void *	operator new (size_t sz)
void *	operator new (size_t sz, void *vp)
void *	operator new[] (size_t sz)
void *	operator new[] (size_t sz, void *vp)
TObject &	operator= (const TObject &rhs)
	TObject assignment operator.
virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself.
virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.
virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.
virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list.
void	ResetBit (UInt_t f)
virtual void	SaveAs (const char *filename="", Option_t *option="") const
	Save this object in the file specified by filename.
virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out".
void	SetBit (UInt_t f)
void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f.
virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object.
virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
virtual void	SysError (const char *method, const char *msgfmt,...) const
	Issue system error message.
R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const
Int_t	TestBits (UInt_t f) const
virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.
virtual void	Warning (const char *method, const char *msgfmt,...) const
	Issue warning message.
virtual Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.
virtual Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.

Static Public Member Functions
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static void	CreateColorsCircle (Int_t offset, const char *name, UChar_t *rgb)
	Create the "circle" colors in the color wheel.
static void	CreateColorsGray ()
	Create the Gray scale colors in the Color Wheel.
static void	CreateColorsRectangle (Int_t offset, const char *name, UChar_t *rgb)
	Create the "rectangular" colors in the color wheel.
static Int_t	CreateColorTableFromFile (TString fileName, Float_t alpha=1.)
	Static function creating a color palette based on an input text file.
static void	CreateColorWheel ()
	Static function steering the creation of all colors in the color wheel.
static Int_t	CreateGradientColorTable (UInt_t Number, Double_t *Stops, Double_t *Red, Double_t *Green, Double_t *Blue, UInt_t NColors, Float_t alpha=1., Bool_t setPalette=kTRUE)
	Static function creating a color table with several connected linear gradients.
static const char *	DeclFileName ()
static Bool_t	DefinedColors (Int_t set_always_on=0)
	Static method returning kTRUE if some new colors have been defined after initialisation or since the last call to this method.
static Int_t	GetColor (const char *hexcolor)
	Static method returning color number for color specified by hex color string of form: "#rrggbb", where rr, gg and bb are in hex between [0,FF], e.g.
static Int_t	GetColor (Float_t r, Float_t g, Float_t b, Float_t a=1.)
	Static method returning color number for color specified by r, g and b.
static Int_t	GetColor (Int_t r, Int_t g, Int_t b, Float_t a=1.)
	Static method returning color number for color specified by r, g and b.
static Int_t	GetColor (ULong_t pixel)
	Static method returning color number for color specified by system dependent pixel value.
static Int_t	GetColorBright (Int_t color)
	Static function: Returns the bright color number corresponding to n If the TColor object does not exist, it is created at a free color index.
static Int_t	GetColorByName (const char *colorname)
	Static method returning color index for a color specified by name.
static Int_t	GetColorDark (Int_t color)
	Static function: Returns the dark color number corresponding to n If the TColor object does not exist, it is created at a free color index.
static Int_t	GetColorPalette (Int_t i)
	Static function returning the color number i in current palette.
static Int_t	GetColorTransparent (Int_t color, Float_t a)
	Static function: Returns the transparent color number corresponding to n.
static Int_t	GetFirstFreeColorIndex ()
	Static function: Returns the first free color greater in the list of colors.
static Int_t	GetFreeColorIndex ()
	Static function: Returns the free color index greater than the highest defined color index.
static Int_t	GetLinearGradient (Double_t angle, const std::vector< Int_t > &colors, const std::vector< Double_t > &positions={})
	Static function: Returns the linear gradient color number corresponding to specified parameters.
static Int_t	GetNumberOfColors ()
	Static function returning number of colors in the color palette.
static const TArrayI &	GetPalette ()
	Static function returning the current active palette.
static Int_t	GetRadialGradient (Double_t r, const std::vector< Int_t > &colors, const std::vector< Double_t > &positions={})
	Static function: Returns the radial gradient color number corresponding to specified parameters.
static void	HLS2RGB (Float_t h, Float_t l, Float_t s, Float_t &r, Float_t &g, Float_t &b)
	Static method to compute RGB from HLS.
static void	HLS2RGB (Int_t h, Int_t l, Int_t s, Int_t &r, Int_t &g, Int_t &b)
	Static method to compute RGB from HLS.
static void	HLStoRGB (Float_t h, Float_t l, Float_t s, Float_t &r, Float_t &g, Float_t &b)
static void	HSV2RGB (Float_t h, Float_t s, Float_t v, Float_t &r, Float_t &g, Float_t &b)
	Static method to compute RGB from HSV:
static void	InitializeColors ()
	Initialize colors used by the TCanvas based graphics (via TColor objects).
static void	InvertPalette ()
	Invert the current color palette.
static Bool_t	IsGrayscale ()
	Return whether all colors return grayscale values.
static void	ListColors (Int_t ci1=0, Int_t ci2=0, Bool_t showEmpty=kFALSE)
	List nb colors from the color index ci.
static ULong_t	Number2Pixel (Int_t ci)
	Static method that given a color index number, returns the corresponding pixel value.
static void	Pixel2RGB (ULong_t pixel, Float_t &r, Float_t &g, Float_t &b)
	Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to r,g,b triplet.
static void	Pixel2RGB (ULong_t pixel, Int_t &r, Int_t &g, Int_t &b)
	Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to r,g,b triplet.
static const char *	PixelAsHexString (ULong_t pixel)
	Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to a hexadecimal string.
static void	RGB2HLS (Float_t r, Float_t g, Float_t b, Float_t &h, Float_t &l, Float_t &s)
	Static method to compute HLS from RGB.
static void	RGB2HLS (Int_t r, Int_t g, Int_t b, Int_t &h, Int_t &l, Int_t &s)
	Static method to compute HLS from RGB.
static void	RGB2HSV (Float_t r, Float_t g, Float_t b, Float_t &h, Float_t &s, Float_t &v)
	Static method to compute HSV from RGB.
static ULong_t	RGB2Pixel (Float_t r, Float_t g, Float_t b)
	Convert r,g,b to graphics system dependent pixel value.
static ULong_t	RGB2Pixel (Int_t r, Int_t g, Int_t b)
	Convert r,g,b to graphics system dependent pixel value.
static void	RGBtoHLS (Float_t r, Float_t g, Float_t b, Float_t &h, Float_t &l, Float_t &s)
static Bool_t	SaveColor (std::ostream &out, Int_t ci)
	Save a color with index > 228 as a C++ statement(s) on output stream out.
static void	SetColorThreshold (Float_t t)
	This method specifies the color threshold used by GetColor to retrieve a color.
static void	SetGrayscale (Bool_t set=kTRUE)
	Set whether all colors should return grayscale values.
static void	SetPalette (Int_t ncolors, Int_t *colors, Float_t alpha=1.)
	Static function.
Static Public Member Functions inherited from TNamed
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
Static Public Member Functions inherited from TObject
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
static Longptr_t	GetDtorOnly ()
	Return destructor only flag.
static Bool_t	GetObjectStat ()
	Get status of object stat flag.
static void	SetDtorOnly (void *obj)
	Set destructor only flag.
static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable.

Protected Attributes
Int_t	fNumber
	Color number identifier.
Protected Attributes inherited from TNamed
TString	fName
TString	fTitle

Private Member Functions
void	Allocate ()
	Make this color known to the graphics system.

Static Private Member Functions
static Float_t	HLStoRGB1 (Float_t rn1, Float_t rn2, Float_t huei)
	Static method. Auxiliary to HLS2RGB().

Private Attributes
Float_t	fAlpha
	Alpha (transparency)
Float_t	fBlue
	Fraction of Blue.
Float_t	fGreen
	Fraction of Green.
Float_t	fHue
	Hue.
Float_t	fLight
	Light.
Float_t	fRed
	Fraction of Red.
Float_t	fSaturation
	Saturation.

Additional Inherited Members
Public Types inherited from TObject
enum	{   kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,   kBitMask = 0x00ffffff }
enum	{ kSingleKey = (1ULL << ( 0 )) , kOverwrite = (1ULL << ( 1 )) , kWriteDelete = (1ULL << ( 2 )) }
enum	EDeprecatedStatusBits { kObjInCanvas = (1ULL << ( 3 )) }
enum	EStatusBits {   kCanDelete = (1ULL << ( 0 )) , kMustCleanup = (1ULL << ( 3 )) , kIsReferenced = (1ULL << ( 4 )) , kHasUUID = (1ULL << ( 5 )) ,   kCannotPick = (1ULL << ( 6 )) , kNoContextMenu = (1ULL << ( 8 )) , kInvalidObject = (1ULL << ( 13 )) }
Protected Types inherited from TObject
enum	{ kOnlyPrepStep = (1ULL << ( 3 )) }
Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char *location, const char *fmt, va_list va) const
	Interface to ErrorHandler (protected).
void	MakeZombie ()

#include <TColor.h>

Inheritance diagram for TColor:

Constructor & Destructor Documentation

TColor() [1/4]

TColor::TColor

(

)

Default constructor.

Definition at line 1061 of file TColor.cxx.

TColor() [2/4]

TColor::TColor	(	Int_t	color,
		Float_t	r,
		Float_t	g,
		Float_t	b,
		const char *	name = "",
		Float_t	a = 1
	)

Normal color constructor.

Initialize a color structure. Compute the RGB and HLS color components. The color title is set to its hexadecimal value.

Definition at line 1073 of file TColor.cxx.

TColor() [3/4]

TColor::TColor	(	Float_t	r,
		Float_t	g,
		Float_t	b,
		Float_t	a = 1
	)

Fast TColor constructor.

It creates a color with an index just above the current highest one. It does not name the color. This is useful to create palettes.

Definition at line 1119 of file TColor.cxx.

TColor() [4/4]

TColor::TColor

(

const TColor &

color

)

Color copy constructor.

Definition at line 1150 of file TColor.cxx.

~TColor()

TColor::~TColor ( )

virtual

Color destructor.

Definition at line 1138 of file TColor.cxx.

Member Function Documentation

Allocate()

void TColor::Allocate ( )

private

Make this color known to the graphics system.

Definition at line 1904 of file TColor.cxx.

AsHexString()

const char * TColor::AsHexString

(

)

const

Return color as hexadecimal string.

This string can be directly passed to, for example, TGClient::GetColorByName(). String will be reused so copy immediately if needed.

Definition at line 1325 of file TColor.cxx.

Class()

static TClass * TColor::Class ( )

static

Returns

TClass describing this class

Class_Name()

static const char * TColor::Class_Name ( )

static

Returns

Name of this class

Class_Version()

static constexpr Version_t TColor::Class_Version ( )

inlinestaticconstexpr

Returns

Version of this class

Definition at line 113 of file TColor.h.

Copy()

void TColor::Copy ( TObject &  color ) const

overridevirtual

Copy this color to obj.

Reimplemented from TObject.

Definition at line 1346 of file TColor.cxx.

CreateColorsCircle()

void TColor::CreateColorsCircle ( Int_t  offset, const char *  name, UChar_t *  rgb  )

static

Create the "circle" colors in the color wheel.

Definition at line 1378 of file TColor.cxx.

CreateColorsGray()

void TColor::CreateColorsGray ( )

static

Create the Gray scale colors in the Color Wheel.

Definition at line 1362 of file TColor.cxx.

CreateColorsRectangle()

void TColor::CreateColorsRectangle ( Int_t  offset, const char *  name, UChar_t *  rgb  )

static

Create the "rectangular" colors in the color wheel.

Definition at line 1397 of file TColor.cxx.

CreateColorTableFromFile()

Int_t TColor::CreateColorTableFromFile ( TString  fileName, Float_t  alpha = 1.  )

static

Static function creating a color palette based on an input text file.

Every color in the file will take the same amount of space in the palette.

See also

https://doi.org/10.1038/s41467-020-19160-7

Note

This function is designed to load into ROOT the colour-vision deficiency friendly and perceptually uniform colour maps specially designed in https://doi.org/10.5281/zenodo.4491293, namely the .txt files stored in the subfolders of ScientificColourMaps7.zip, e.g. batlow/batlow.txt

Parameters

fileName	Name of a .txt file (ASCII) containing three floats per line, separated by spaces, namely the r g b fractions of the color, each value being in the range [0,1].
alpha	the global opacity for all colors within this palette

Returns

a positive value on success and -1 on error.

Author

Fernando Hueso-González

Definition at line 2624 of file TColor.cxx.

CreateColorWheel()

void TColor::CreateColorWheel ( )

static

Static function steering the creation of all colors in the color wheel.

Definition at line 1416 of file TColor.cxx.

CreateGradientColorTable()

Int_t TColor::CreateGradientColorTable ( UInt_t  Number, Double_t *  Stops, Double_t *  Red, Double_t *  Green, Double_t *  Blue, UInt_t  NColors, Float_t  alpha = 1., Bool_t  setPalette = kTRUE  )

static

Static function creating a color table with several connected linear gradients.

• Number: The number of end point colors that will form the gradients. Must be at least 2.
• Stops: Where in the whole table the end point colors should lie. Each entry must be on [0, 1], each entry must be greater than the previous entry.
• Red, Green, Blue: The end point color values. Each entry must be on [0, 1]
• NColors: Total number of colors in the table. Must be at least 1.
• alpha: the opacity factor, between 0 and 1. Default is no transparency (1).
• setPalette: activate the newly created palette (true by default). If false, the caller is in charge of calling TColor::SetPalette using the return value of the function (first palette color index) and reconstructing the Int_t palette[NColors+1] array.

Returns a positive value (the index of the first color of the palette) on success and -1 on error.

The table is constructed by tracing lines between the given points in RGB space. Each color value may have a value between 0 and 1. The difference between consecutive "Stops" values gives the fraction of space in the whole table that should be used for the interval between the corresponding color values.

Normally the first element of Stops should be 0 and the last should be 1. If this is not true, fewer than NColors will be used in proportion with the total interval between the first and last elements of Stops.

This definition is similar to the povray-definition of gradient color tables.

For instance:

UInt_t Number = 3;
Double_t Red[3]   = { 0.0, 1.0, 1.0 };
Double_t Green[3] = { 0.0, 0.0, 1.0 };
Double_t Blue[3]  = { 1.0, 0.0, 1.0 };
Double_t Stops[3] = { 0.0, 0.4, 1.0 };

This defines a table in which there are three color end points: RGB = {0, 0, 1}, {1, 0, 0}, and {1, 1, 1} = blue, red, white The first 40% of the table is used to go linearly from blue to red. The remaining 60% of the table is used to go linearly from red to white.

If you define a very short interval such that less than one color fits in it, no colors at all will be allocated. If this occurs for all intervals, ROOT will revert to the default palette.

Original code by Andreas Zoglauer (zog@m.nosp@m.pe.m.nosp@m.pg.de)

Definition at line 2730 of file TColor.cxx.

DeclFileName()

static const char * TColor::DeclFileName ( )

inlinestatic

Returns

Name of the file containing the class declaration

Definition at line 113 of file TColor.h.

DefinedColors()

Bool_t TColor::DefinedColors ( Int_t  set_always_on = 0 )

static

Static method returning kTRUE if some new colors have been defined after initialisation or since the last call to this method.

This allows to avoid the colors and palette streaming in TCanvas::Streamer if not needed. If method called once with set_always_on = 1, all next canvases will be To reset such mode, just call methoid once with set_always_on = -1

Definition at line 1537 of file TColor.cxx.

GetAlpha()

Float_t TColor::GetAlpha ( ) const

inline

Definition at line 66 of file TColor.h.

GetBlue()

Float_t TColor::GetBlue ( ) const

inline

Definition at line 62 of file TColor.h.

GetColor() [1/4]

Int_t TColor::GetColor ( const char *  hexcolor )

static

Static method returning color number for color specified by hex color string of form: "#rrggbb", where rr, gg and bb are in hex between [0,FF], e.g.

"#c0c0c0".

The color retrieval is done using a threshold defined by SetColorThreshold.

If specified color does not exist it will be created with as name "#rrggbb" with rr, gg and bb in hex between [0,FF].

Definition at line 1920 of file TColor.cxx.

GetColor() [2/4]

Int_t TColor::GetColor ( Float_t  r, Float_t  g, Float_t  b, Float_t  a = 1.  )

static

Static method returning color number for color specified by r, g and b.

The r,g,b should be in the range [0,1].

The color retrieval is done using a threshold defined by SetColorThreshold.

If specified color does not exist it will be created with as name "#rrggbb" with rr, gg and bb in hex between [0,FF].

Definition at line 1941 of file TColor.cxx.

GetColor() [3/4]

Int_t TColor::GetColor ( Int_t  r, Int_t  g, Int_t  b, Float_t  a = 1.  )

static

Static method returning color number for color specified by r, g and b.

The r,g,b should be in the range [0,255]. If the specified color does not exist it will be created with as name "#rrggbb" with rr, gg and bb in hex between [0,FF].

The color retrieval is done using a threshold defined by SetColorThreshold.

Definition at line 2001 of file TColor.cxx.

GetColor() [4/4]

Int_t TColor::GetColor ( ULong_t  pixel )

static

Static method returning color number for color specified by system dependent pixel value.

Pixel values can be obtained, e.g., from the GUI color picker.

The color retrieval is done using a threshold defined by SetColorThreshold.

Definition at line 1954 of file TColor.cxx.

GetColorBright()

Int_t TColor::GetColorBright ( Int_t  color )

static

Static function: Returns the bright color number corresponding to n If the TColor object does not exist, it is created at a free color index.

Definition at line 2087 of file TColor.cxx.

GetColorByName()

Int_t TColor::GetColorByName ( const char *  colorname )

static

Static method returning color index for a color specified by name.

The list of defined colors and their names is given by TColor::ListColors. If the specified color name does not exist -1 is returned.

Definition at line 2073 of file TColor.cxx.

GetColorDark()

Int_t TColor::GetColorDark ( Int_t  color )

static

Static function: Returns the dark color number corresponding to n If the TColor object does not exist, it is created at a free color index.

Definition at line 2130 of file TColor.cxx.

GetColorPalette()

Int_t TColor::GetColorPalette ( Int_t  i )

static

Static function returning the color number i in current palette.

Definition at line 1504 of file TColor.cxx.

GetColorTransparent()

Int_t TColor::GetColorTransparent ( Int_t  n, Float_t  a  )

static

Static function: Returns the transparent color number corresponding to n.

The opacity level is given by the alpha value a. If a color with the same RGBa values already exists it is returned.

Definition at line 2174 of file TColor.cxx.

GetFirstFreeColorIndex()

Int_t TColor::GetFirstFreeColorIndex ( )

static

Static function: Returns the first free color greater in the list of colors.

index. It can be used to define a user custom color.

Int_t ci = TColor::GetFirstFreeColorIndex();
auto color = new TColor(ci, 0.1, 0.2, 0.3);

Definition at line 2378 of file TColor.cxx.

GetFreeColorIndex()

Int_t TColor::GetFreeColorIndex ( )

static

Static function: Returns the free color index greater than the highest defined color index.

All the color indices after this index are also free. It can be used to define a user custom color.

Int_t ci = TColor::GetFreeColorIndex();
auto color = new TColor(ci, 0.1, 0.2, 0.3);

Definition at line 2364 of file TColor.cxx.

GetGrayscale()

virtual Float_t TColor::GetGrayscale ( ) const

inlinevirtual

Definition at line 67 of file TColor.h.

GetGreen()

Float_t TColor::GetGreen ( ) const

inline

Definition at line 61 of file TColor.h.

GetHLS()

virtual void TColor::GetHLS ( Float_t &  h, Float_t &  l, Float_t &  s  ) const

inlinevirtual

Definition at line 56 of file TColor.h.

GetHue()

Float_t TColor::GetHue ( ) const

inline

Definition at line 63 of file TColor.h.

GetLight()

Float_t TColor::GetLight ( ) const

inline

Definition at line 64 of file TColor.h.

GetLinearGradient()

Int_t TColor::GetLinearGradient ( Double_t  angle, const std::vector< Int_t > &  colors, const std::vector< Double_t > &  positions = {}  )

static

Static function: Returns the linear gradient color number corresponding to specified parameters.

First parameter set direction as angle in grad. Value 0 is horizontal direction, 90 - vertical List of colors defines interpolation colors for the gradient Optional positions can define relative color positions and must be sorted array of values between 0 and 1. If such gradient not exists - it will be created new Returns -1 if wrong parameters where specified

Definition at line 2210 of file TColor.cxx.

GetNumber()

Int_t TColor::GetNumber ( ) const

inline

Definition at line 58 of file TColor.h.

GetNumberOfColors()

Int_t TColor::GetNumberOfColors ( )

static

Static function returning number of colors in the color palette.

Definition at line 1524 of file TColor.cxx.

GetPalette()

const TArrayI & TColor::GetPalette ( )

static

Static function returning the current active palette.

Definition at line 1516 of file TColor.cxx.

GetPixel()

ULong_t TColor::GetPixel

(

)

const

Return pixel value corresponding to this color.

This pixel value can be used in the GUI classes. This call does not work in batch mode since it needs to communicate with the graphics system.

Definition at line 1559 of file TColor.cxx.

GetRadialGradient()

Int_t TColor::GetRadialGradient ( Double_t  radius, const std::vector< Int_t > &  colors, const std::vector< Double_t > &  positions = {}  )

static

Static function: Returns the radial gradient color number corresponding to specified parameters.

First parameter set direction as angle in grad. Value 0 is horizontal direction, 90 - vertical List of colors defines interpolation colors for the gradient Optional positions can define relative color positions and must be sorted array of values between 0 and 1. If such gradient not exists - it will be created new Returns -1 if wrong parameter where specified

Definition at line 2287 of file TColor.cxx.

GetRed()

Float_t TColor::GetRed ( ) const

inline

Definition at line 60 of file TColor.h.

GetRGB()

virtual void TColor::GetRGB ( Float_t &  r, Float_t &  g, Float_t &  b  ) const

inlinevirtual

Definition at line 54 of file TColor.h.

GetSaturation()

Float_t TColor::GetSaturation ( ) const

inline

Definition at line 65 of file TColor.h.

HLS2RGB() [1/2]

void TColor::HLS2RGB ( Float_t  hue, Float_t  light, Float_t  satur, Float_t &  r, Float_t &  g, Float_t &  b  )

static

Static method to compute RGB from HLS.

The l and s are between [0,1] and h is between [0,360]. The returned r,g,b triplet is between [0,1].

Definition at line 1576 of file TColor.cxx.

HLS2RGB() [2/2]

void TColor::HLS2RGB ( Int_t  h, Int_t  l, Int_t  s, Int_t &  r, Int_t &  g, Int_t &  b  )

static

Static method to compute RGB from HLS.

The h,l,s are between [0,255]. The returned r,g,b triplet is between [0,255].

Definition at line 1616 of file TColor.cxx.

HLStoRGB()

static void TColor::HLStoRGB ( Float_t  h, Float_t  l, Float_t  s, Float_t &  r, Float_t &  g, Float_t &  b  )

inlinestatic

Definition at line 77 of file TColor.h.

HLStoRGB1()

Float_t TColor::HLStoRGB1 ( Float_t  rn1, Float_t  rn2, Float_t  huei  )

staticprivate

Static method. Auxiliary to HLS2RGB().

Definition at line 1601 of file TColor.cxx.

HSV2RGB()

void TColor::HSV2RGB ( Float_t  hue, Float_t  satur, Float_t  value, Float_t &  r, Float_t &  g, Float_t &  b  )

static

Static method to compute RGB from HSV:

• The hue value runs from 0 to 360.
• The saturation is the degree of strength or purity and is from 0 to 1. Purity is how much white is added to the color, so S=1 makes the purest color (no white).
• Brightness value also ranges from 0 to 1, where 0 is the black.

The returned r,g,b triplet is between [0,1].

Definition at line 1642 of file TColor.cxx.

InitializeColors()

void TColor::InitializeColors ( )

static

Initialize colors used by the TCanvas based graphics (via TColor objects).

This method should be called before the ApplicationImp is created (which initializes the GUI colors).

Definition at line 1167 of file TColor.cxx.

InvertPalette()

void TColor::InvertPalette ( )

static

Invert the current color palette.

The top of the palette becomes the bottom and vice versa.

Definition at line 3640 of file TColor.cxx.

IsA()

TClass * TColor::IsA ( ) const

inlineoverridevirtual

Returns

TClass describing current object

Reimplemented from TObject.

Reimplemented in TColorGradient, TLinearGradient, and TRadialGradient.

Definition at line 113 of file TColor.h.

IsGrayscale()

Bool_t TColor::IsGrayscale ( )

static

Return whether all colors return grayscale values.

Definition at line 2584 of file TColor.cxx.

ListColors()

void TColor::ListColors ( Int_t  ci = 0, Int_t  nb = 0, Bool_t  showEmpty = kFALSE  )

static

List nb colors from the color index ci.

If nb=0 all the colors are printed. If showEmpty is set to kTRUE, empty color indices are also printed

Definition at line 2395 of file TColor.cxx.

ls()

void TColor::ls ( Option_t *  option = "" ) const

overridevirtual

List this color with its attributes.

Reimplemented from TObject.

Definition at line 1698 of file TColor.cxx.

Number2Pixel()

ULong_t TColor::Number2Pixel ( Int_t  ci )

static

Static method that given a color index number, returns the corresponding pixel value.

This pixel value can be used in the GUI classes. This call does not work in batch mode since it needs to communicate with the graphics system.

Definition at line 2437 of file TColor.cxx.

operator=()

TColor & TColor::operator=

(

const TColor &

color

)

Definition at line 1155 of file TColor.cxx.

Pixel2RGB() [1/2]

void TColor::Pixel2RGB ( ULong_t  pixel, Float_t &  r, Float_t &  g, Float_t &  b  )

static

Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to r,g,b triplet.

The r,g,b triplet will be [0,1].

Definition at line 2498 of file TColor.cxx.

Pixel2RGB() [2/2]

void TColor::Pixel2RGB ( ULong_t  pixel, Int_t &  r, Int_t &  g, Int_t &  b  )

static

Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to r,g,b triplet.

The r,g,b triplet will be [0,255].

Definition at line 2513 of file TColor.cxx.

PixelAsHexString()

const char * TColor::PixelAsHexString ( ULong_t  pixel )

static

Convert machine dependent pixel value (obtained via RGB2Pixel or via Number2Pixel() or via TColor::GetPixel()) to a hexadecimal string.

This string can be directly passed to, for example, TGClient::GetColorByName(). String will be reused so copy immediately if needed.

Definition at line 2530 of file TColor.cxx.

Print()

void TColor::Print ( Option_t *  option = "" ) const

overridevirtual

Dump this color with its attributes.

Reimplemented from TObject.

Definition at line 1707 of file TColor.cxx.

RGB2HLS() [1/2]

void TColor::RGB2HLS ( Float_t  rr, Float_t  gg, Float_t  bb, Float_t &  hue, Float_t &  light, Float_t &  satur  )

static

Static method to compute HLS from RGB.

The r,g,b triplet is between [0,1], hue is between [0,360], light and satur are [0,1].

Definition at line 1716 of file TColor.cxx.

RGB2HLS() [2/2]

void TColor::RGB2HLS ( Int_t  r, Int_t  g, Int_t  b, Int_t &  h, Int_t &  l, Int_t &  s  )

static

Static method to compute HLS from RGB.

The r,g,b triplet is between [0,255], hue, light and satur are between [0,255].

Definition at line 1806 of file TColor.cxx.

RGB2HSV()

void TColor::RGB2HSV ( Float_t  r, Float_t  g, Float_t  b, Float_t &  hue, Float_t &  satur, Float_t &  value  )

static

Static method to compute HSV from RGB.

• The input values:
  • r,g,b triplet is between [0,1].
• The returned values:
  • The hue value runs from 0 to 360.
  • The saturation is the degree of strength or purity and is from 0 to 1. Purity is how much white is added to the color, so S=1 makes the purest color (no white).
  • Brightness value also ranges from 0 to 1, where 0 is the black.

Definition at line 1771 of file TColor.cxx.

RGB2Pixel() [1/2]

ULong_t TColor::RGB2Pixel ( Float_t  r, Float_t  g, Float_t  b  )

static

Convert r,g,b to graphics system dependent pixel value.

The r,g,b triplet must be [0,1].

Definition at line 2453 of file TColor.cxx.

RGB2Pixel() [2/2]

ULong_t TColor::RGB2Pixel ( Int_t  r, Int_t  g, Int_t  b  )

static

Convert r,g,b to graphics system dependent pixel value.

The r,g,b triplet must be [0,255].

Definition at line 2475 of file TColor.cxx.

RGBtoHLS()

static void TColor::RGBtoHLS ( Float_t  r, Float_t  g, Float_t  b, Float_t &  h, Float_t &  l, Float_t &  s  )

inlinestatic

Definition at line 82 of file TColor.h.

SaveColor()

Bool_t TColor::SaveColor ( std::ostream &  out, Int_t  ci  )

static

Save a color with index > 228 as a C++ statement(s) on output stream out.

Return kFALSE if color not saved in the output stream

Definition at line 2543 of file TColor.cxx.

SetAlpha()

virtual void TColor::SetAlpha ( Float_t  a )

inlinevirtual

Definition at line 70 of file TColor.h.

SetColorThreshold()

void TColor::SetColorThreshold ( Float_t  t )

static

This method specifies the color threshold used by GetColor to retrieve a color.

Parameters

[in]

t

Color threshold. By default is equal to 1./31. or 1./255. depending on the number of available color planes.

When GetColor is called, it scans the defined colors and compare them to the requested color. If the Red Green and Blue values passed to GetColor are Rr Gr Br and Rd Gd Bd the values of a defined color. These two colors are considered equal if (abs(Rr-Rd) < t & abs(Br-Bd) < t & abs(Br-Bd) < t). If this test passes, the color defined by Rd Gd Bd is returned by GetColor.

To make sure GetColor will return a color having exactly the requested R G B values it is enough to specify a nul :

TColor::SetColorThreshold(0.);

To reset the color threshold to its default value it is enough to do:

TColor::SetColorThreshold(-1.);

Definition at line 1987 of file TColor.cxx.

SetGrayscale()

void TColor::SetGrayscale ( Bool_t  set = kTRUE )

static

Set whether all colors should return grayscale values.

Definition at line 2592 of file TColor.cxx.

SetName()

void TColor::SetName ( const char *  name )

overridevirtual

Set the color name and change also the name of the "dark" and "bright" associated colors if they exist.

Reimplemented from TNamed.

Definition at line 1826 of file TColor.cxx.

SetPalette()

void TColor::SetPalette ( Int_t  ncolors, Int_t *  colors, Float_t  alpha = 1.  )

static

Static function.

The color palette is used by the histogram classes (see TH1::Draw options). For example TH1::Draw("col") draws a 2-D histogram with cells represented by a box filled with a color CI function of the cell content. if the cell content is N, the color CI used will be the color number in colors[N],etc. If the maximum cell content is > ncolors, all cell contents are scaled to ncolors.

if ncolors <= 0 a default palette (see below) of 50 colors is defined. The colors defined in this palette are OK for coloring pads, labels.

index 0->9   : grey colors from light to dark grey
index 10->19 : "brown" colors
index 20->29 : "blueish" colors
index 30->39 : "redish" colors
index 40->49 : basic colors

if ncolors == 1 && colors == 0, a Rainbow Color map is created with 50 colors. It is kept for backward compatibility. Better palettes like kBird are recommended.

High quality predefined palettes with 255 colors are available when colors == 0. The following value of ncolors give access to:

if ncolors = 51 and colors=0, a Deep Sea palette is used.
if ncolors = 52 and colors=0, a Grey Scale palette is used.
if ncolors = 53 and colors=0, a Dark Body Radiator palette is used.
if ncolors = 54 and colors=0, a Two-Color Hue palette is used.(dark blue through neutral gray to bright yellow)
if ncolors = 55 and colors=0, a Rain Bow palette is used.
if ncolors = 56 and colors=0, an Inverted Dark Body Radiator palette is used.
if ncolors = 57 and colors=0, a monotonically increasing L value palette is used.
if ncolors = 58 and colors=0, a Cubehelix palette is used
                                (Cf. Dave Green's "cubehelix" colour scheme at http://www.mrao.cam.ac.uk/~dag/CUBEHELIX/)
if ncolors = 59 and colors=0, a Green Red Violet palette is used.
if ncolors = 60 and colors=0, a Blue Red Yellow palette is used.
if ncolors = 61 and colors=0, an Ocean palette is used.
if ncolors = 62 and colors=0, a Color Printable On Grey palette is used.
if ncolors = 63 and colors=0, an Alpine palette is used.
if ncolors = 64 and colors=0, an Aquamarine palette is used.
if ncolors = 65 and colors=0, an Army palette is used.
if ncolors = 66 and colors=0, an Atlantic palette is used.
if ncolors = 67 and colors=0, an Aurora palette is used.
if ncolors = 68 and colors=0, an Avocado palette is used.
if ncolors = 69 and colors=0, a Beach palette is used.
if ncolors = 70 and colors=0, a Black Body palette is used.
if ncolors = 71 and colors=0, a Blue Green Yellow palette is used.
if ncolors = 72 and colors=0, a Brown Cyan palette is used.
if ncolors = 73 and colors=0, a CMYK palette is used.
if ncolors = 74 and colors=0, a Candy palette is used.
if ncolors = 75 and colors=0, a Cherry palette is used.
if ncolors = 76 and colors=0, a Coffee palette is used.
if ncolors = 77 and colors=0, a Dark Rain Bow palette is used.
if ncolors = 78 and colors=0, a Dark Terrain palette is used.
if ncolors = 79 and colors=0, a Fall palette is used.
if ncolors = 80 and colors=0, a Fruit Punch palette is used.
if ncolors = 81 and colors=0, a Fuchsia palette is used.
if ncolors = 82 and colors=0, a Grey Yellow palette is used.
if ncolors = 83 and colors=0, a Green Brown Terrain palette is used.
if ncolors = 84 and colors=0, a Green Pink palette is used.
if ncolors = 85 and colors=0, an Island palette is used.
if ncolors = 86 and colors=0, a Lake palette is used.
if ncolors = 87 and colors=0, a Light Temperature palette is used.
if ncolors = 88 and colors=0, a Light Terrain palette is used.
if ncolors = 89 and colors=0, a Mint palette is used.
if ncolors = 90 and colors=0, a Neon palette is used.
if ncolors = 91 and colors=0, a Pastel palette is used.
if ncolors = 92 and colors=0, a Pearl palette is used.
if ncolors = 93 and colors=0, a Pigeon palette is used.
if ncolors = 94 and colors=0, a Plum palette is used.
if ncolors = 95 and colors=0, a Red Blue palette is used.
if ncolors = 96 and colors=0, a Rose palette is used.
if ncolors = 97 and colors=0, a Rust palette is used.
if ncolors = 98 and colors=0, a Sandy Terrain palette is used.
if ncolors = 99 and colors=0, a Sienna palette is used.
if ncolors = 100 and colors=0, a Solar palette is used.
if ncolors = 101 and colors=0, a South West palette is used.
if ncolors = 102 and colors=0, a Starry Night palette is used.
if ncolors = 103 and colors=0, a Sunset palette is used.
if ncolors = 104 and colors=0, a Temperature Map palette is used.
if ncolors = 105 and colors=0, a Thermometer palette is used.
if ncolors = 106 and colors=0, a Valentine palette is used.
if ncolors = 107 and colors=0, a Visible Spectrum palette is used.
if ncolors = 108 and colors=0, a Water Melon palette is used.
if ncolors = 109 and colors=0, a Cool palette is used.
if ncolors = 110 and colors=0, a Copper palette is used.
if ncolors = 111 and colors=0, a Gist Earth palette is used.
if ncolors = 112 and colors=0, a Viridis palette is used.
if ncolors = 113 and colors=0, a Cividis palette is used.

These palettes can also be accessed by names:

kDeepSea=51,          kGreyScale=52,    kDarkBodyRadiator=53,
kBlueYellow= 54,      kRainBow=55,      kInvertedDarkBodyRadiator=56,
kBird=57,             kCubehelix=58,    kGreenRedViolet=59,
kBlueRedYellow=60,    kOcean=61,        kColorPrintableOnGrey=62,
kAlpine=63,           kAquamarine=64,   kArmy=65,
kAtlantic=66,         kAurora=67,       kAvocado=68,
kBeach=69,            kBlackBody=70,    kBlueGreenYellow=71,
kBrownCyan=72,        kCMYK=73,         kCandy=74,
kCherry=75,           kCoffee=76,       kDarkRainBow=77,
kDarkTerrain=78,      kFall=79,         kFruitPunch=80,
kFuchsia=81,          kGreyYellow=82,   kGreenBrownTerrain=83,
kGreenPink=84,        kIsland=85,       kLake=86,
kLightTemperature=87, kLightTerrain=88, kMint=89,
kNeon=90,             kPastel=91,       kPearl=92,
kPigeon=93,           kPlum=94,         kRedBlue=95,
kRose=96,             kRust=97,         kSandyTerrain=98,
kSienna=99,           kSolar=100,       kSouthWest=101,
kStarryNight=102,     kSunset=103,      kTemperatureMap=104,
kThermometer=105,     kValentine=106,   kVisibleSpectrum=107,
kWaterMelon=108,      kCool=109,        kCopper=110,
kGistEarth=111        kViridis=112,     kCividis=113

For example:

gStyle->SetPalette(kBird);

Set the current palette as "Bird" (number 57).

The color numbers specified in the palette can be viewed by selecting the item "colors" in the "VIEW" menu of the canvas toolbar. The color parameters can be changed via TColor::SetRGB.

Note that when drawing a 2D histogram h2 with the option "COL" or "COLZ" or with any "CONT" options using the color map, the number of colors used is defined by the number of contours n specified with: h2->SetContour(n)

Definition at line 2921 of file TColor.cxx.

SetRGB()

void TColor::SetRGB ( Float_t  r, Float_t  g, Float_t  b  )

virtual

Initialize this color and its "dark" and "bright" associated colors.

Definition at line 1850 of file TColor.cxx.

Streamer()

void TColor::Streamer ( TBuffer &  R__b )

overridevirtual

Stream an object of class TObject.

Reimplemented from TObject.

Reimplemented in TColorGradient, TLinearGradient, and TRadialGradient.

StreamerNVirtual()

void TColor::StreamerNVirtual ( TBuffer &  ClassDef_StreamerNVirtual_b )

inline

Definition at line 113 of file TColor.h.

Member Data Documentation

fAlpha

Float_t TColor::fAlpha

private

Alpha (transparency)

Definition at line 31 of file TColor.h.

fBlue

Float_t TColor::fBlue

private

Fraction of Blue.

Definition at line 27 of file TColor.h.

fGreen

Float_t TColor::fGreen

private

Fraction of Green.

Definition at line 26 of file TColor.h.

fHue

Float_t TColor::fHue

private

Hue.

Definition at line 28 of file TColor.h.

fLight

Float_t TColor::fLight

private

Light.

Definition at line 29 of file TColor.h.

fNumber

Int_t TColor::fNumber

protected

Color number identifier.

Definition at line 23 of file TColor.h.

fRed

Float_t TColor::fRed

private

Fraction of Red.

Definition at line 25 of file TColor.h.

fSaturation

Float_t TColor::fSaturation

private

Saturation.

Definition at line 30 of file TColor.h.

Libraries for TColor:

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The documentation for this class was generated from the following files:

• core/base/inc/TColor.h
• core/base/src/TColor.cxx