Logo ROOT   6.16/01
Reference Guide
radialgradients.C File Reference

Detailed Description

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

Requires ROOT built for OS X with –enable-cocoa.

//Includes for ACLiC:
#include <cassert>
#include <cstdlib>
#include "TColorGradient.h"
#include "TVirtualX.h"
#include "TEllipse.h"
#include "TRandom.h"
#include "TCanvas.h"
#include "TError.h"
//Cocoa aux. functions.
#include "customcolor.h"
namespace {
//Just some colors (rgba) to build our
//fancy gradients from.
const Double_t basicColors[][4] =
{
{1., 0., 0., 1.},
{1., 0.3, 0., 1.},
{0., 0., 1., 1.},
{1., 1., 0., 1.},
{1., 0., 1., 1.},
{0., 1., 1., 1.},
{0., 1., 0., 1.},
{0., 0.5, 0., 1.},
//transparent colors:
{1., 0., 0., 0.5},
{1., 0.3, 0., 0.5},
{0., 0., 1., 0.5},
{1., 1., 0., 0.5},
{1., 0., 1., 0.5},
{0., 1., 1., 0.5},
{0., 1., 0., 0.5},
{0., 0.5, 0., 0.5},
//and even more transparent:
{1., 0., 0., 0.2},
{1., 0.3, 0., 0.2},
{0., 0., 1., 0.2},
{1., 1., 0., 0.2},
{1., 0., 1., 0.2},
{0., 1., 1., 0.2},
{0., 1., 0., 0.2},
{0., 0.5, 0., 0.2}
};
const unsigned nBasicColors = sizeof basicColors / sizeof basicColors[0];
//______________________________________________________________________
Color_t CreateRandomGradientFill()
{
Color_t idx[1] = {};
return -1;
const Double_t * const fromRGBA = basicColors[(std::rand() % (nBasicColors / 2))];
//With odd number of colors the last one is never selected :)
const Double_t * const toRGBA = basicColors[nBasicColors / 2 + (std::rand() % (nBasicColors / 2))];
const Double_t locations[] = {0., 1.};
const Double_t rgbas[] = {fromRGBA[0], fromRGBA[1], fromRGBA[2], fromRGBA[3],
toRGBA[0], toRGBA[1], toRGBA[2], toRGBA[3]};
TRadialGradient * const grad = new TRadialGradient(idx[0], 2, locations, rgbas);
return idx[0];
}
//______________________________________________________________________
bool add_ellipse(const Double_t xC, const Double_t yC, const Double_t r)
{
assert(gPad != nullptr && "add_ellipse, no pad to add ellipse");
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()
{
gRandom->SetSeed(4357);//;)
TCanvas * const cnv = new TCanvas("radial gradients", "radial gradients", 800, 800);
if (gVirtualX && !gVirtualX->InheritsFrom("TGCocoa")) {
::Error("radialgradients",
"this demo requires OS X and ROOT built with --enable-cocoa");
delete cnv;
return;
}
for (unsigned i = 0; i < 100; ++i)
if (!add_ellipse(gRandom->Rndm(), gRandom->Rndm(), 0.5 * gRandom->Rndm()))
break;
cnv->Modified();
cnv->Update();
}
ROOT::R::TRInterface & r
Definition: Object.C:4
double Double_t
Definition: RtypesCore.h:55
short Color_t
Definition: RtypesCore.h:79
void Error(const char *location, const char *msgfmt,...)
R__EXTERN TRandom * gRandom
Definition: TRandom.h:62
#define gPad
Definition: TVirtualPad.h:286
#define gVirtualX
Definition: TVirtualX.h:345
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
The Canvas class.
Definition: TCanvas.h:31
virtual void Update()
Update canvas pad buffers.
Definition: TCanvas.cxx:2286
Draw Ellipses.
Definition: TEllipse.h:24
virtual void Draw(Option_t *option="")
Draw this ellipse with its current attributes.
Definition: TEllipse.cxx:166
void Modified(Bool_t flag=1)
Definition: TPad.h:415
Define a radial color gradient.
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:589
virtual Double_t Rndm()
Machine independent random number generator.
Definition: TRandom.cxx:533
unsigned FindFreeCustomColorIndices(Color_t(&indices)[N])
Definition: customcolor.h:38
Author
Timur Pocheptsov

Definition in file radialgradients.C.