haiku/headers/libs/agg/agg_span_gradient.h

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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//----------------------------------------------------------------------------
#ifndef AGG_SPAN_GRADIENT_INCLUDED
#define AGG_SPAN_GRADIENT_INCLUDED
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "agg_basics.h"
#include "agg_math.h"
#include "agg_array.h"
namespace agg
{
enum gradient_subpixel_scale_e
{
gradient_subpixel_shift = 4, //-----gradient_subpixel_shift
gradient_subpixel_scale = 1 << gradient_subpixel_shift, //-----gradient_subpixel_scale
gradient_subpixel_mask = gradient_subpixel_scale - 1 //-----gradient_subpixel_mask
};
//==========================================================span_gradient
template<class ColorT,
class Interpolator,
class GradientF,
class ColorF>
class span_gradient
{
public:
typedef Interpolator interpolator_type;
typedef ColorT color_type;
enum downscale_shift_e
{
downscale_shift = interpolator_type::subpixel_shift -
gradient_subpixel_shift
};
//--------------------------------------------------------------------
span_gradient() {}
//--------------------------------------------------------------------
span_gradient(interpolator_type& inter,
const GradientF& gradient_function,
const ColorF& color_function,
double d1, double d2) :
m_interpolator(&inter),
m_gradient_function(&gradient_function),
m_color_function(&color_function),
m_d1(iround(d1 * gradient_subpixel_scale)),
m_d2(iround(d2 * gradient_subpixel_scale))
{}
//--------------------------------------------------------------------
interpolator_type& interpolator() { return *m_interpolator; }
const GradientF& gradient_function() const { return *m_gradient_function; }
const ColorF& color_function() const { return *m_color_function; }
double d1() const { return double(m_d1) / gradient_subpixel_scale; }
double d2() const { return double(m_d2) / gradient_subpixel_scale; }
//--------------------------------------------------------------------
void interpolator(interpolator_type& i) { m_interpolator = &i; }
void gradient_function(const GradientF& gf) { m_gradient_function = &gf; }
void color_function(const ColorF& cf) { m_color_function = &cf; }
void d1(double v) { m_d1 = iround(v * gradient_subpixel_scale); }
void d2(double v) { m_d2 = iround(v * gradient_subpixel_scale); }
//--------------------------------------------------------------------
void prepare() {}
//--------------------------------------------------------------------
void generate(color_type* span, int x, int y, unsigned len)
{
int dd = m_d2 - m_d1;
if(dd < 1) dd = 1;
m_interpolator->begin(x+0.5, y+0.5, len);
do
{
m_interpolator->coordinates(&x, &y);
int d = m_gradient_function->calculate(x >> downscale_shift,
y >> downscale_shift, m_d2);
d = ((d - m_d1) * (int)m_color_function->size()) / dd;
if(d < 0) d = 0;
if(d >= (int)m_color_function->size()) d = m_color_function->size() - 1;
*span++ = (*m_color_function)[d];
++(*m_interpolator);
}
while(--len);
}
private:
interpolator_type* m_interpolator;
const GradientF* m_gradient_function;
const ColorF* m_color_function;
int m_d1;
int m_d2;
};
//=====================================================gradient_linear_color
template<class ColorT>
struct gradient_linear_color
{
typedef ColorT color_type;
gradient_linear_color() {}
gradient_linear_color(const color_type& c1, const color_type& c2,
unsigned size = 256) :
m_c1(c1), m_c2(c2), m_size(size) {}
unsigned size() const { return m_size; }
color_type operator [] (unsigned v) const
{
return m_c1.gradient(m_c2, double(v) / double(m_size - 1));
}
void colors(const color_type& c1, const color_type& c2, unsigned size = 256)
{
m_c1 = c1;
m_c2 = c2;
m_size = size;
}
color_type m_c1;
color_type m_c2;
unsigned m_size;
};
//==========================================================gradient_circle
class gradient_circle
{
// Actually the same as radial. Just for compatibility
public:
static AGG_INLINE int calculate(int x, int y, int)
{
return int(fast_sqrt(x*x + y*y));
}
};
//==========================================================gradient_radial
class gradient_radial
{
public:
static AGG_INLINE int calculate(int x, int y, int)
{
return int(fast_sqrt(x*x + y*y));
}
};
//========================================================gradient_radial_d
class gradient_radial_d
{
public:
static AGG_INLINE int calculate(int x, int y, int)
{
return uround(sqrt(double(x)*double(x) + double(y)*double(y)));
}
};
//====================================================gradient_radial_focus
class gradient_radial_focus
{
public:
//---------------------------------------------------------------------
gradient_radial_focus() :
m_radius(100 * gradient_subpixel_scale),
m_focus_x(0),
m_focus_y(0)
{
update_values();
}
//---------------------------------------------------------------------
gradient_radial_focus(double r, double fx, double fy) :
m_radius (iround(r * gradient_subpixel_scale)),
m_focus_x(iround(fx * gradient_subpixel_scale)),
m_focus_y(iround(fy * gradient_subpixel_scale))
{
update_values();
}
//---------------------------------------------------------------------
void init(double r, double fx, double fy)
{
m_radius = iround(r * gradient_subpixel_scale);
m_focus_x = iround(fx * gradient_subpixel_scale);
m_focus_y = iround(fy * gradient_subpixel_scale);
update_values();
}
//---------------------------------------------------------------------
double radius() const { return double(m_radius) / gradient_subpixel_scale; }
double focus_x() const { return double(m_focus_x) / gradient_subpixel_scale; }
double focus_y() const { return double(m_focus_y) / gradient_subpixel_scale; }
//---------------------------------------------------------------------
int calculate(int x, int y, int) const
{
double solution_x;
double solution_y;
// Special case to avoid divide by zero or very near zero
//---------------------------------
if(x == iround(m_focus_x))
{
solution_x = m_focus_x;
solution_y = 0.0;
solution_y += (y > m_focus_y) ? m_trivial : -m_trivial;
}
else
{
// Slope of the focus-current line
//-------------------------------
double slope = double(y - m_focus_y) / double(x - m_focus_x);
// y-intercept of that same line
//--------------------------------
double yint = double(y) - (slope * x);
// Use the classical quadratic formula to calculate
// the intersection point
//--------------------------------
double a = (slope * slope) + 1;
double b = 2 * slope * yint;
double c = yint * yint - m_radius2;
double det = sqrt((b * b) - (4.0 * a * c));
solution_x = -b;
// Choose the positive or negative root depending
// on where the X coord lies with respect to the focus.
solution_x += (x < m_focus_x) ? -det : det;
solution_x /= 2.0 * a;
// Calculating of Y is trivial
solution_y = (slope * solution_x) + yint;
}
// Calculate the percentage (0...1) of the current point along the
// focus-circumference line and return the normalized (0...d) value
//-------------------------------
solution_x -= double(m_focus_x);
solution_y -= double(m_focus_y);
double int_to_focus = solution_x * solution_x + solution_y * solution_y;
double cur_to_focus = double(x - m_focus_x) * double(x - m_focus_x) +
double(y - m_focus_y) * double(y - m_focus_y);
return iround(sqrt(cur_to_focus / int_to_focus) * m_radius);
}
private:
//---------------------------------------------------------------------
void update_values()
{
// For use in the quadratic equation
//-------------------------------
m_radius2 = double(m_radius) * double(m_radius);
double dist = sqrt(double(m_focus_x) * double(m_focus_x) +
double(m_focus_y) * double(m_focus_y));
// Test if distance from focus to center is greater than the radius
// For the sake of assurance factor restrict the point to be
// no further than 99% of the radius.
//-------------------------------
double r = m_radius * 0.99;
if(dist > r)
{
// clamp focus to radius
// x = r cos theta, y = r sin theta
//------------------------
double a = atan2(double(m_focus_y), double(m_focus_x));
m_focus_x = iround(r * cos(a));
m_focus_y = iround(r * sin(a));
}
// Calculate the solution to be used in the case where x == focus_x
//------------------------------
m_trivial = sqrt(m_radius2 - (m_focus_x * m_focus_x));
}
int m_radius;
int m_focus_x;
int m_focus_y;
double m_radius2;
double m_trivial;
};
//==============================================================gradient_x
class gradient_x
{
public:
static int calculate(int x, int, int) { return x; }
};
//==============================================================gradient_y
class gradient_y
{
public:
static int calculate(int, int y, int) { return y; }
};
//========================================================gradient_diamond
class gradient_diamond
{
public:
static AGG_INLINE int calculate(int x, int y, int)
{
int ax = abs(x);
int ay = abs(y);
return ax > ay ? ax : ay;
}
};
//=============================================================gradient_xy
class gradient_xy
{
public:
static AGG_INLINE int calculate(int x, int y, int d)
{
return abs(x) * abs(y) / d;
}
};
//========================================================gradient_sqrt_xy
class gradient_sqrt_xy
{
public:
static AGG_INLINE int calculate(int x, int y, int)
{
return fast_sqrt(abs(x) * abs(y));
}
};
//==========================================================gradient_conic
class gradient_conic
{
public:
static AGG_INLINE int calculate(int x, int y, int d)
{
return uround(fabs(atan2(double(y), double(x))) * double(d) / pi);
}
};
//=================================================gradient_repeat_adaptor
template<class GradientF> class gradient_repeat_adaptor
{
public:
gradient_repeat_adaptor(const GradientF& gradient) :
m_gradient(&gradient) {}
AGG_INLINE int calculate(int x, int y, int d) const
{
int ret = m_gradient->calculate(x, y, d) % d;
if(ret < 0) ret += d;
return ret;
}
private:
const GradientF* m_gradient;
};
//================================================gradient_reflect_adaptor
template<class GradientF> class gradient_reflect_adaptor
{
public:
gradient_reflect_adaptor(const GradientF& gradient) :
m_gradient(&gradient) {}
AGG_INLINE int calculate(int x, int y, int d) const
{
int d2 = d << 1;
int ret = m_gradient->calculate(x, y, d) % d2;
if(ret < 0) ret += d2;
if(ret >= d) ret = d2 - ret;
return ret;
}
private:
const GradientF* m_gradient;
};
}
#endif