TAttImage.cxx

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// @(#)root/graf:$Id$
// Author: Reiner Rohlfs   24/03/02
 
/*************************************************************************
 * Copyright (C) 2001-2001, Rene Brun, Fons Rademakers and Reiner Rohlfs *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
/** \class TAttImage
\ingroup BasicGraphics
\ingroup GraphicsAtt
 
TImage attributes.
 
Image attributes are:
 
- Image Quality (see EImageQuality for the list of qualities)
- Compression defines the compression rate of the color data in the
  internal image structure. Speed and memory depends
  on this rate, but not the image display itself
  0: no compression;  100: max compression
- Radio Flag: kTRUE  the x/y radio of the displayed image is always
  identical to the original image kFALSE the x and y size of the displayed
  image depends on the size of the pad
- Palette: Defines the conversion from a pixel value to the
  screen color
 
This class is used (in general by secondary inheritance)
by some other classes (image display).
*/
 
/** \class TImagePalette
\ingroup BasicGraphics
 
A class to define a conversion from pixel values to pixel color.
 
A Palette is defined by some anchor points. Each anchor point has
a value between 0 and 1 and a color. An image has to be normalized
and the values between the anchor points are interpolated.
All member variables are public and can be directly manipulated.
In most cases the default operator will be used to create a
TImagePalette. In this case the member arrays have to be allocated
by an application and will be deleted in the destructor of this
class.
 
We provide few predefined palettes:
 
- gHistImagePalette - palette used in TH2::Draw("col")
- gWebImagePalette
  The web palette is a set of 216 colors that will not dither or
  shift on PCs or Macs. Browsers use this built-in palette when
  they need to render colors on monitors with only 256 colors
  (also called 8-bit color monitors).
  The 6x6x6 web palette provides very quick color index lookup
  and can be used for good quality conversion of images into
  2-D histograms.
- TImagePalette(Int_t ncolors, Int_t *colors)
  if ncolors <= 0 a default palette (see below) of 50 colors
  is defined.
 
if ncolors == 1 && colors == 0, then a Rainbow Palette is created.
 
if ncolors > 50 and colors=0, the DeepSea palette is used.
(see TStyle::CreateGradientColorTable for more details)
 
if ncolors > 0 and colors = 0, the default palette is used with a maximum of ncolors.
 
The default palette defines:
- 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
*/
 
/** \class TPaletteEditor
\ingroup BasicGraphics
 
Edit the palette via a GUI.
 
This class provides a way to edit the palette via a GUI.
*/
 
 
#include "TAttImage.h"
#include "TROOT.h"
#include "TPluginManager.h"
#include <iostream>
#include "TColor.h"
#include "TMath.h"
#include "TStyle.h"
#include <vector>
 
ClassImp(TPaletteEditor);
ClassImp(TAttImage);
ClassImp(TImagePalette);
 
 
// definition of a default palette
const Int_t kNUM_DEFAULT_COLORS = 12;
static UShort_t gAlphaDefault[kNUM_DEFAULT_COLORS] = {
   0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff,
   0xffff, 0xffff, 0xffff, 0xffff
};
 
static UShort_t gRedDefault[kNUM_DEFAULT_COLORS] = {
   0x0000, 0x0000, 0x7000, 0x0000, 0x0000, 0x0000, 0xffff, 0xffff,
   0x7000, 0x8000, 0xffff, 0xffff
};
 
static UShort_t gGreenDefault[kNUM_DEFAULT_COLORS] = {
   0x0000, 0x0000, 0x0000, 0x0000, 0xffff, 0xffff, 0xffff, 0x0000,
   0x0000, 0x8000, 0xffff, 0xffff
};
 
static UShort_t gBlueDefault[kNUM_DEFAULT_COLORS] = {
   0x0000, 0x0000, 0x7000, 0xffff, 0xffff, 0x0000, 0x0000, 0x0000,
   0x0000, 0xa000, 0xffff, 0xffff
};
 
 
//////////////////////////// Web Palette ///////////////////////////////////////
static UShort_t gWebBase[6] = { 0, 51, 102, 153, 204, 255 };
 
class TWebPalette : public TImagePalette {
 
private:
   Int_t fCLUT[6][6][6];   // Color LookUp Table
 
public:
   TWebPalette() : TImagePalette() {
      int i = 0;
      fNumPoints = 216;
      fPoints = new Double_t[216];
      fColorRed = new UShort_t[216];
      fColorBlue = new UShort_t[216];
      fColorGreen = new UShort_t[216];
      fColorAlpha = new UShort_t[216];
 
      for (i = 0; i < 214; i++) {
         fPoints[i + 1]  =  (double)i/213;
      }
      fPoints[0] = 0;
      fPoints[215] = 1;
 
      i = 0;
      for (int r = 0; r < 6; r++) {
         for (int g = 0; g < 6; g++) {
            for (int b = 0; b < 6; b++) {
               fColorRed[i] = gWebBase[r] << 8;
               fColorGreen[i] = gWebBase[g] << 8;
               fColorBlue[i] = gWebBase[b] << 8;
               fColorAlpha[i] = 0xffff;
               fCLUT[r][g][b] = i;
               i++;
            }
         }
      }
   }
 
   Int_t FindColor(UShort_t r, UShort_t g, UShort_t b) override
   {
      Int_t ri = TMath:: BinarySearch(6, (const Short_t*)gWebBase, (Short_t)r);
      Int_t gi = TMath:: BinarySearch(6, (const Short_t*)gWebBase, (Short_t)g);
      Int_t bi = TMath:: BinarySearch(6, (const Short_t*)gWebBase, (Short_t)b);
      return fCLUT[ri][gi][bi];
   }
 
   Int_t *GetRootColors() override
   {
      static std::vector<Int_t> gRootColors;
      if (!gRootColors.empty())
         return gRootColors.data();
 
      gRootColors.resize(216);
 
      int i = 0;
      for (int r = 0; r < 6; r++) {
         for (int g = 0; g < 6; g++) {
            for (int b = 0; b < 6; b++) {
               gRootColors[i] = TColor::GetColor(gWebBase[r], gWebBase[g], gWebBase[b]);
               i++;
            }
         }
      }
      return gRootColors.data();
   }
};
 
TImagePalette *gWebImagePalette = new TWebPalette();
 
 
////////////////////////////// Hist Palette ////////////////////////////////////
static Double_t gDefHistP[50] =  {
      0.00,0.02,0.04,0.06,0.08,0.10,0.12,0.14,0.16,0.18,0.20,0.22,0.24,0.26,
      0.28,0.30,0.32,0.34,0.36,0.38,0.40,0.42,0.44,0.46,0.48,0.50,0.52,0.54,
      0.56,0.58,0.60,0.62,0.64,0.66,0.68,0.70,0.72,0.74,0.76,0.78,0.80,0.82,
      0.84,0.86,0.88,0.90,0.92,0.94,0.96,0.98 };
 
static UShort_t gDefHistR[50] = {
      242,229,204,178,153,127,102,76,192,204,204,193,186,178,183,173,155,135,
      175,132,89,137,130,173,122, 117,104,109,124,127,170,89,211,221,188,198,
      191,170,165,147,206,211,255,0,255,255,0,0,53,0 };
 
static UShort_t gDefHistG[50] = {
      242,229,204,178,153,127,102,76,182,198,198,191,181,165,163,153,142,102,
      206,193,211,168,158,188,142,137,130,122,153,127,165,84,206,186,158,153,
      130,142,119,104,94,89,0,255,0,255,0,255,53,0 };
 
static UShort_t gDefHistB[50] = {
      242,229,204,178,153,127,102,76,172,170,170,168,163,150,155,140,130,86,
      198,163,84,160,140,198,153,145,150,132,209,155,191,216,135,135,130,124,
      119,147,122,112,96,84,0,255,255,0,255,0,53,0 };
 
static UShort_t gDefHistA[50] = {
      255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
      255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
      255,255,255,255,255,255,255,255,255,255,255,255,255,255 };
 
static Int_t gDefHistRoot[50] = {
      19,18,17,16,15,14,13,12,11,20,21,22,23,24,25,26,27,28,29,30, 8,
      31,32,33,34,35,36,37,38,39,40, 9, 41,42,43,44,45,47,48,49,46,50, 2,
      7, 6, 5, 4, 3, 112,1};
 
 
class TDefHistImagePalette : public TImagePalette {
 
public:
   TDefHistImagePalette() : TImagePalette() {
      fNumPoints = 50;
      fPoints = gDefHistP;
      fColorRed = gDefHistR;
      fColorGreen = gDefHistG;
      fColorBlue = gDefHistB;
      fColorAlpha = gDefHistA;
 
      for (int i = 0; i<50; i++) {
         fColorRed[i] = fColorRed[i] << 8;
         fColorGreen[i] = fColorGreen[i] << 8;
         fColorBlue[i] = fColorBlue[i] << 8;
         fColorAlpha[i] = fColorAlpha[i] << 8;
      }
   }
 
   Int_t *GetRootColors() override { return gDefHistRoot; }
};
 
TImagePalette *gHistImagePalette = new TDefHistImagePalette();
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor.
 
TPaletteEditor::TPaletteEditor(TAttImage *attImage, UInt_t, UInt_t)
{
   fAttImage = attImage;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Closes the window and deletes itself.
 
void TPaletteEditor::CloseWindow()
{
   fAttImage->EditorClosed();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Default constructor, sets all pointers to 0.
 
TImagePalette::TImagePalette()
{
}
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor for a palette with numPoints anchor points.
/// It allocates the memory but does not set any colors.
 
TImagePalette::TImagePalette(UInt_t numPoints)
{
   fNumPoints  = numPoints;
   fPoints     = new Double_t[fNumPoints];
   fColorRed   = new UShort_t[fNumPoints];
   fColorGreen = new UShort_t[fNumPoints];
   fColorBlue  = new UShort_t[fNumPoints];
   fColorAlpha = new UShort_t[fNumPoints];
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor.
 
TImagePalette::TImagePalette(const TImagePalette &palette) : TObject(palette)
{
   fNumPoints = palette.fNumPoints;
 
   fPoints = new Double_t[fNumPoints];
   memcpy(fPoints, palette.fPoints, fNumPoints * sizeof(Double_t));
 
   fColorRed   = new UShort_t[fNumPoints];
   fColorGreen = new UShort_t[fNumPoints];
   fColorBlue  = new UShort_t[fNumPoints];
   fColorAlpha = new UShort_t[fNumPoints];
   memcpy(fColorRed,   palette.fColorRed,   fNumPoints * sizeof(UShort_t));
   memcpy(fColorGreen, palette.fColorGreen, fNumPoints * sizeof(UShort_t));
   memcpy(fColorBlue,  palette.fColorBlue,  fNumPoints * sizeof(UShort_t));
   memcpy(fColorAlpha, palette.fColorAlpha, fNumPoints * sizeof(UShort_t));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Creates palette in the same way as TStyle::SetPalette
 
TImagePalette::TImagePalette(Int_t ncolors, Int_t *colors)
{
   Int_t i;
   static Int_t palette[50] = {19,18,17,16,15,14,13,12,11,20,
                        21,22,23,24,25,26,27,28,29,30, 8,
                        31,32,33,34,35,36,37,38,39,40, 9,
                        41,42,43,44,45,47,48,49,46,50, 2,
                         7, 6, 5, 4, 3, 112,1};
   TColor *col = nullptr;
   Float_t step = 0;
   // set default palette (pad type)
   if (ncolors <= 0) {
      ncolors = 50;
      fNumPoints  = ncolors;
      step = 1./fNumPoints;
      fPoints     = new Double_t[fNumPoints];
      fColorRed   = new UShort_t[fNumPoints];
      fColorGreen = new UShort_t[fNumPoints];
      fColorBlue  = new UShort_t[fNumPoints];
      fColorAlpha = new UShort_t[fNumPoints];
      for (i=0;i<ncolors;i++) {
         col = gROOT->GetColor(palette[i]);
         fPoints[i] = i*step;
         if (col) {
            fColorRed[i]   = UShort_t(col->GetRed()*255)  << 8;
            fColorGreen[i] = UShort_t(col->GetGreen()*255) << 8;
            fColorBlue[i]  = UShort_t(col->GetBlue()*255) << 8;
         }
         fColorAlpha[i] = 65280;
      }
      return;
   }
 
   // set Pretty Palette Spectrum Violet->Red
   if (ncolors == 1 && !colors) {
      ncolors = 50;
      fNumPoints  = ncolors;
      step = 1./fNumPoints;
      fPoints     = new Double_t[fNumPoints];
      fColorRed   = new UShort_t[fNumPoints];
      fColorGreen = new UShort_t[fNumPoints];
      fColorBlue  = new UShort_t[fNumPoints];
      fColorAlpha = new UShort_t[fNumPoints];
 
      // 0 point is white
      fPoints[0] = 0;
      fColorRed[0] = 255 << 8;
      fColorGreen[0] = 255 << 8;
      fColorBlue[0] = 255 << 8;
      fColorAlpha[0] = 0;
 
      for (i=1;i<ncolors;i++) {
         col = gROOT->GetColor(51+i);
         fPoints[i] = i*step;
         if (col) {
            fColorRed[i]   = UShort_t(col->GetRed()*255) << 8;
            fColorGreen[i] = UShort_t(col->GetGreen()*255) << 8;
            fColorBlue[i]  = UShort_t(col->GetBlue()*255) << 8;
         }
         fColorAlpha[i] = 65280;
      }
      return;
   }
 
   // set DeepSea palette
   if (!colors && ncolors > 50) {
      static const Int_t nRGBs = 5;
      static Float_t stops[nRGBs] = { 0.00, 0.34, 0.61, 0.84, 1.00 };
      static Float_t red[nRGBs] = { 0.00, 0.09, 0.18, 0.09, 0.00 };
      static Float_t green[nRGBs] = { 0.01, 0.02, 0.39, 0.68, 0.97 };
      static Float_t blue[nRGBs] = { 0.17, 0.39, 0.62, 0.79, 0.97 };
      fNumPoints = nRGBs;
      fPoints     = new Double_t[fNumPoints];
      fColorRed   = new UShort_t[fNumPoints];
      fColorGreen = new UShort_t[fNumPoints];
      fColorBlue  = new UShort_t[fNumPoints];
      fColorAlpha = new UShort_t[fNumPoints];
      for (i=0;i<(int)fNumPoints;i++) {
         fPoints[i] = stops[i];
         fColorRed[i] = UShort_t(red[i]*255) << 8;
         fColorGreen[i] = UShort_t(green[i]*255) << 8;
         fColorBlue[i] = UShort_t(blue[i]*255) << 8;
         fColorAlpha[i] = 65280;
      }
      return;
   }
 
   // set user defined palette
   if (colors)  {
      fNumPoints  = ncolors;
      step = 1./fNumPoints;
      fPoints     = new Double_t[fNumPoints];
      fColorRed   = new UShort_t[fNumPoints];
      fColorGreen = new UShort_t[fNumPoints];
      fColorBlue  = new UShort_t[fNumPoints];
      fColorAlpha = new UShort_t[fNumPoints];
      for (i=0;i<ncolors;i++) {
         fPoints[i] = i*step;
         col = gROOT->GetColor(colors[i]);
         if (col) {
            fColorRed[i] = UShort_t(col->GetRed()*255) << 8;
            fColorGreen[i] = UShort_t(col->GetGreen()*255) << 8;
            fColorBlue[i] = UShort_t(col->GetBlue()*255) << 8;
            fColorAlpha[i] = 65280;
         } else {
            fColorRed[i] = 0;
            fColorGreen[i] = 0;
            fColorBlue[i] = 0;
            fColorAlpha[i] = 0;
         }
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Destructor.
 
TImagePalette::~TImagePalette()
{
   delete [] fPoints;
   delete [] fColorRed;
   delete [] fColorGreen;
   delete [] fColorBlue;
   delete [] fColorAlpha;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Assignment operator.
 
TImagePalette &TImagePalette::operator=(const TImagePalette &palette)
{
   if (this != &palette) {
      fNumPoints = palette.fNumPoints;
 
      delete [] fPoints;
      fPoints = new Double_t[fNumPoints];
      memcpy(fPoints, palette.fPoints, fNumPoints * sizeof(Double_t));
 
      delete [] fColorRed;
      fColorRed = new UShort_t[fNumPoints];
      memcpy(fColorRed, palette.fColorRed, fNumPoints * sizeof(UShort_t));
 
      delete [] fColorGreen;
      fColorGreen = new UShort_t[fNumPoints];
      memcpy(fColorGreen, palette.fColorGreen, fNumPoints * sizeof(UShort_t));
 
      delete [] fColorBlue;
      fColorBlue = new UShort_t[fNumPoints];
      memcpy(fColorBlue, palette.fColorBlue, fNumPoints * sizeof(UShort_t));
 
      delete [] fColorAlpha;
      fColorAlpha = new UShort_t[fNumPoints];
      memcpy(fColorAlpha, palette.fColorAlpha, fNumPoints * sizeof(UShort_t));
   }
 
   return *this;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns an index of the closest color
 
Int_t TImagePalette::FindColor(UShort_t r, UShort_t g, UShort_t b)
{
   Int_t ret = 0;
   UInt_t d = 10000;
   UInt_t min = 10000;
 
   for (UInt_t i = 0; i < fNumPoints; i++) {
      d = TMath::Abs(r - ((fColorRed[i] & 0xff00) >> 8)) +
          TMath::Abs(g - ((fColorGreen[i] & 0xff00) >> 8)) +
          TMath::Abs(b - ((fColorBlue[i] & 0xff00) >> 8));
      if (d < min) {
         min = d;
         ret = i;
      }
   }
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns a list of ROOT colors. Could be used to set histogram palette.
/// See also TStyle::SetPalette
 
Int_t *TImagePalette::GetRootColors()
{
   static std::vector<Int_t> gRootColors;
   if (!gRootColors.empty())
      return gRootColors.data();
 
   gRootColors.resize(fNumPoints);
 
   for (UInt_t i = 0; i < fNumPoints; i++)
      gRootColors[i] = TColor::GetColor(fColorRed[i], fColorGreen[i], fColorBlue[i]);
 
   return gRootColors.data();
}
 
////////////////////////////////////////////////////////////////////////////////
/// TAttImage default constructor.
/// Calls ResetAttImage to set the attributes to a default state.
 
TAttImage::TAttImage()
{
   ResetAttImage();
   fPaletteEditor = nullptr;
   fPaletteEnabled = kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// TAttImage normal constructor.
/// Image attributes are taken from the argument list
///
/// \param[in] lquality   must be one of EImageQuality (kImgDefault is same as
///                   kImgGood in the current implementation)
/// \param[in] lcompression   defines the compression rate of the color data in the
///                   image. Speed and memory depends on this rate, but not
///                   the image display itself
///                   0: no compression;  100: max compression
/// \param[in] constRatio  keeps the aspect ratio of the image constant on the
///                   screen (in pixel units)
 
TAttImage::TAttImage(EImageQuality lquality, UInt_t lcompression,
                     Bool_t constRatio)
{
   ResetAttImage();
 
   fImageQuality = lquality;
   fImageCompression = (lcompression > 100) ? 100 : lcompression;
   fConstRatio = constRatio;
   fPaletteEditor = nullptr;
   fPaletteEnabled = kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// TAttImage destructor.
 
TAttImage::~TAttImage()
{
   delete fPaletteEditor;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy this image attributes to a new attimage.
 
void TAttImage::Copy(TAttImage &attimage) const
{
   attimage.fImageQuality     = fImageQuality;
   attimage.fImageCompression = fImageCompression;
   attimage.fConstRatio       = fConstRatio;
   attimage.fPalette          = fPalette;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Reset this image attributes to default values.
/// Default values are:
///
/// - quality:     kImgPoor, (no smoothing while the image is zoomed)
/// - compression: 0 (no compression)
/// - constRatio:  kTRUE
/// - palette:     a default rainbow palette
 
void TAttImage::ResetAttImage(Option_t *)
{
   fImageQuality      = kImgPoor;
   fImageCompression  = 0;
   fConstRatio        = kTRUE;
 
   // set the default palette
   delete [] fPalette.fPoints;
   delete [] fPalette.fColorRed;
   delete [] fPalette.fColorGreen;
   delete [] fPalette.fColorBlue;
   delete [] fPalette.fColorAlpha;
 
   fPalette.fNumPoints = kNUM_DEFAULT_COLORS;
 
   fPalette.fColorRed    = new UShort_t [kNUM_DEFAULT_COLORS];
   fPalette.fColorGreen  = new UShort_t [kNUM_DEFAULT_COLORS];
   fPalette.fColorBlue   = new UShort_t [kNUM_DEFAULT_COLORS];
   fPalette.fColorAlpha  = new UShort_t [kNUM_DEFAULT_COLORS];
   fPalette.fPoints      = new Double_t [kNUM_DEFAULT_COLORS];
 
   memcpy(fPalette.fColorRed,   gRedDefault,   kNUM_DEFAULT_COLORS * sizeof(UShort_t));
   memcpy(fPalette.fColorGreen, gGreenDefault, kNUM_DEFAULT_COLORS * sizeof(UShort_t));
   memcpy(fPalette.fColorBlue,  gBlueDefault,  kNUM_DEFAULT_COLORS * sizeof(UShort_t));
   memcpy(fPalette.fColorAlpha, gAlphaDefault, kNUM_DEFAULT_COLORS * sizeof(UShort_t));
 
   for (Int_t point = 0; point < kNUM_DEFAULT_COLORS - 2; point++)
      fPalette.fPoints[point + 1]  =  (double)point / (kNUM_DEFAULT_COLORS - 3);
   fPalette.fPoints[0] = 0;
   fPalette.fPoints[kNUM_DEFAULT_COLORS - 1] = 1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Save image attributes as C++ statement(s) on output stream, but
/// not the palette.
 
void TAttImage::SaveImageAttributes(std::ostream &out, const char *name,
                                    EImageQuality qualdef,
                                    UInt_t comprdef, Bool_t constRatiodef)
{
   if (fImageQuality != qualdef) {
      out<<"   "<<name<<"->SetImageQuality("<<fImageQuality<<");"<<std::endl;
   }
   if (fImageCompression != comprdef) {
      out<<"   "<<name<<"->SetImageCompression("<<fImageCompression<<");"<<std::endl;
   }
   if (fConstRatio != constRatiodef) {
      out<<"   "<<name<<"->SetConstRatio("<<fConstRatio<<");"<<std::endl;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set (constRatio = kTRUE) or unset (constRadio = kFALSE) the ratio flag.
/// The aspect ratio of the image on the screen is constant if the ratio
/// flag is set. That means one image pixel is always a square on the screen
/// independent of the pad size and of the size of the zoomed area.
 
void TAttImage::SetConstRatio(Bool_t constRatio)
{
   fConstRatio = constRatio;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set a new palette for the image. If palette == 0 a default
/// rainbow color palette is used.
 
void TAttImage::SetPalette(const TImagePalette *palette)
{
   if (palette)
      fPalette = *palette;
   else {
      // set default palette
 
      delete [] fPalette.fPoints;
      delete [] fPalette.fColorRed;
      delete [] fPalette.fColorGreen;
      delete [] fPalette.fColorBlue;
      delete [] fPalette.fColorAlpha;
 
      fPalette.fNumPoints = kNUM_DEFAULT_COLORS;
 
      fPalette.fColorRed    = new UShort_t [kNUM_DEFAULT_COLORS];
      fPalette.fColorGreen  = new UShort_t [kNUM_DEFAULT_COLORS];
      fPalette.fColorBlue   = new UShort_t [kNUM_DEFAULT_COLORS];
      fPalette.fColorAlpha  = new UShort_t [kNUM_DEFAULT_COLORS];
      fPalette.fPoints      = new Double_t [kNUM_DEFAULT_COLORS];
 
      memcpy(fPalette.fColorRed,   gRedDefault,   kNUM_DEFAULT_COLORS * sizeof(UShort_t));
      memcpy(fPalette.fColorGreen, gGreenDefault, kNUM_DEFAULT_COLORS * sizeof(UShort_t));
      memcpy(fPalette.fColorBlue,  gBlueDefault,  kNUM_DEFAULT_COLORS * sizeof(UShort_t));
      memcpy(fPalette.fColorAlpha, gAlphaDefault, kNUM_DEFAULT_COLORS * sizeof(UShort_t));
 
      for (Int_t point = 0; point < kNUM_DEFAULT_COLORS - 2; point++)
         fPalette.fPoints[point + 1]  =  (double)point / (kNUM_DEFAULT_COLORS - 3);
      fPalette.fPoints[0] = 0;
      fPalette.fPoints[kNUM_DEFAULT_COLORS - 1] = 1;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Factory method to creates an image palette of a specific typ
///
/// Create a new palette
///
///  This creates a new TImagePalette based on the
///  option specified in the parameter. The supported options are:
///
///  - "col"   - color palette similar in TStyle (i.e. use for "col" option)
///  - "web"   - color palette similar to gWebImagePalette
///  - "hist"  - color palette similar to gHistImagePalette
///
///  \param opts   the type of palette to create
///
///  Ownership of the returned object transfers to the caller.
///
///  \retval new palette
///  \retval nullptr - option does not exist
 
TImagePalette* TImagePalette::Create(Option_t* opts)
{
   TImagePalette* pPalette = nullptr;
 
   TString option(opts);
   if (option.Contains("col", TString::kIgnoreCase)) {
      // Define the new palette using the current palette in TStyle
      pPalette = new TImagePalette(gStyle->GetNumberOfColors());
      Double_t step = 1./(pPalette->fNumPoints-1);
 
      for (UInt_t i=0; i<pPalette->fNumPoints; ++i) {
         TColor* pColor = gROOT->GetColor(gStyle->GetColorPalette(i));
         pPalette->fPoints[i] = i*step;
         if (pColor) {
            pPalette->fColorRed[i] = UShort_t(pColor->GetRed()*255) << 8;
            pPalette->fColorGreen[i] = UShort_t(pColor->GetGreen()*255) << 8;
            pPalette->fColorBlue[i] = UShort_t(pColor->GetBlue()*255) << 8;
         }
         pPalette->fColorAlpha[i] = 0xff00;
      }
   } else if (option.Contains("web", TString::kIgnoreCase)) {
      pPalette = new TDefHistImagePalette();
   } else if (option.Contains("hist", TString::kIgnoreCase)) {
      pPalette = new TWebPalette();
   }
 
   return pPalette;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Factory method to creates an image palette for histogram plotting.
///
/// Creates a "col" palette with correct number of contours
///
/// The behavior is similar to the TImagePalette::Create() method with
/// the "col" option. The difference here is that the palette will only
/// contain a specific number of colors. This method is used to create
/// the palette used in the "col2" and "colz2" options. It handles the
/// color selection for contours.
///
/// \param ncontours   number of contours
///
/// Ownership of the returned object transfers to the caller.
///
/// \return new palette
 
TImagePalette* TImagePalette::CreateCOLPalette(Int_t ncontours)
{
   Int_t ncolors  = gStyle->GetNumberOfColors();
   Int_t minColor = 0;
   Double_t scale = 1;
   if (ncontours != 0 ) {
      minColor = (0.99*ncolors)/ncontours;
      scale = static_cast<Double_t>(ncolors)/ncontours;
      ncolors  = ncontours;
   }
 
   // Define the new palette using the current palette in TStyle
   auto pPalette = new TImagePalette(ncolors);
   Double_t step = 1./(pPalette->fNumPoints-1);
 
   for (UInt_t i=0; i<pPalette->fNumPoints; ++i) {
      TColor* pColor = gROOT->GetColor(gStyle->GetColorPalette(minColor + i*scale));
      pPalette->fPoints[i] = i*step;
      if (pColor) {
         pPalette->fColorRed[i] = UShort_t(pColor->GetRed()*255) << 8;
         pPalette->fColorGreen[i] = UShort_t(pColor->GetGreen()*255) << 8;
         pPalette->fColorBlue[i] = UShort_t(pColor->GetBlue()*255) << 8;
         pPalette->fColorAlpha[i] = UShort_t(pColor->GetAlpha()*255) << 8;
      }
   }
 
   return pPalette;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Opens a GUI to edit the color palette.
 
void TAttImage::StartPaletteEditor()
{
   if (!fPaletteEditor)
      if (auto h = gROOT->GetPluginManager()->FindHandler("TPaletteEditor")) {
         if (h->LoadPlugin() == -1)
            return;
         fPaletteEditor = (TPaletteEditor *) h->ExecPlugin(3, this, 80, 25);
      }
}