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radialgradients.C File Reference

Detailed Description

This tutorial demonstrates how to use radial gradients, custom colors, transparency.

Requires OpenGL or Web-based canvas

// Includes for ACLiC:
#include "TColorGradient.h"
#include "TEllipse.h"
#include "TRandom.h"
#include "TCanvas.h"
#include "TStyle.h"
#include "TError.h"
//______________________________________________________________________
Color_t CreateRandomGradientFill()
{
std::vector<Int_t> colors;
for (int n = 0; n < 2; ++n)
colors.emplace_back(gRandom->Integer(10) + 2);
auto indx = TColor::GetRadialGradient(0.5, colors);
// example how to modify gradient
auto gradient = dynamic_cast<TRadialGradient *>(gROOT->GetColor(indx));
if (gradient) {
// change center and radius
gradient->SetRadialGradient({0.3, 0.3}, 0.7);
// change alpha parameter for the colors
gradient->SetColorAlpha(0, 0.2 + gRandom->Rndm() * 0.8);
gradient->SetColorAlpha(1, 0.2 + gRandom->Rndm() * 0.8);
} else {
::Error("CreateRandomGradientFill", "failed to find new gradient color with index %d", indx);
}
return indx;
}
//______________________________________________________________________
bool add_ellipse(const Double_t xC, const Double_t yC, const Double_t r)
{
const Color_t newColor = CreateRandomGradientFill();
if (newColor == -1) {
::Error("add_ellipse", "failed to find a new color index for a gradient fill");
return false;
}
TEllipse *const newEllipse = new TEllipse(xC, yC, r, r);
newEllipse->SetFillColor(newColor);
newEllipse->Draw();
return true;
}
//______________________________________________________________________
void radialgradients(bool gl = true)
{
gRandom->SetSeed(4357);
auto cnv = new TCanvas("radialgradients", "radial gradients", 800, 800);
if (!cnv->UseGL() && !cnv->IsWeb())
::Warning("radialgradients",
"This macro requires either OpenGL or Web canvas to correctly handle gradient colors");
for (unsigned i = 0; i < 100; ++i)
add_ellipse(gRandom->Rndm(), gRandom->Rndm(), 0.5 * gRandom->Rndm());
}
short Color_t
Definition RtypesCore.h:85
double Double_t
Definition RtypesCore.h:59
void Error(const char *location, const char *msgfmt,...)
Use this function in case an error occurred.
Definition TError.cxx:185
void Warning(const char *location, const char *msgfmt,...)
Use this function in warning situations.
Definition TError.cxx:229
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t r
#define gROOT
Definition TROOT.h:406
R__EXTERN TRandom * gRandom
Definition TRandom.h:62
R__EXTERN TStyle * gStyle
Definition TStyle.h:436
Color * colors
Definition X3DBuffer.c:21
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition TAttFill.h:37
The Canvas class.
Definition TCanvas.h:23
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.
Definition TColor.cxx:2288
Draw Ellipses.
Definition TEllipse.h:23
void Draw(Option_t *option="") override
Draw this ellipse with its current attributes.
Definition TEllipse.cxx:169
void SetRadialGradient(const Point &center, Double_t radius)
Set radial gradient.
virtual void SetSeed(ULong_t seed=0)
Set the random generator seed.
Definition TRandom.cxx:615
Double_t Rndm() override
Machine independent random number generator.
Definition TRandom.cxx:559
virtual UInt_t Integer(UInt_t imax)
Returns a random integer uniformly distributed on the interval [ 0, imax-1 ].
Definition TRandom.cxx:361
void SetCanvasPreferGL(Bool_t prefer=kTRUE)
Definition TStyle.h:341
const Int_t n
Definition legend1.C:16
Authors
Timur Pocheptsov, Sergey Linev

Definition in file radialgradients.C.