headers/libs/agg/agg_span_gradient.h

   1 //----------------------------------------------------------------------------
   2 // Anti-Grain Geometry - Version 2.4
   3 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
   4 //
   5 // Permission to copy, use, modify, sell and distribute this software
   6 // is granted provided this copyright notice appears in all copies.
   7 // This software is provided "as is" without express or implied
   8 // warranty, and with no claim as to its suitability for any purpose.
   9 //
  10 //----------------------------------------------------------------------------
  11 // Contact: mcseem@antigrain.com
  12 //          mcseemagg@yahoo.com
  13 //          http://www.antigrain.com
  14 //----------------------------------------------------------------------------
  15
  16 #ifndef AGG_SPAN_GRADIENT_INCLUDED
  17 #define AGG_SPAN_GRADIENT_INCLUDED
  18
  19 #include <math.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include "agg_basics.h"
  23 #include "agg_math.h"
  24 #include "agg_array.h"
  25
  26
  27 namespace agg
  28 {
  29
  30     enum gradient_subpixel_scale_e
  31     {
  32         gradient_subpixel_shift = 4,                              //-----gradient_subpixel_shift
  33         gradient_subpixel_scale = 1 << gradient_subpixel_shift,   //-----gradient_subpixel_scale
  34         gradient_subpixel_mask  = gradient_subpixel_scale - 1     //-----gradient_subpixel_mask
  35     };
  36
  37
  38
  39     //==========================================================span_gradient
  40     template<class ColorT,
  41              class Interpolator,
  42              class GradientF,
  43              class ColorF>
  44     class span_gradient
  45     {
  46     public:
  47         typedef Interpolator interpolator_type;
  48         typedef ColorT color_type;
  49
  50         enum downscale_shift_e
  51         {
  52             downscale_shift = interpolator_type::subpixel_shift -
  53                               gradient_subpixel_shift
  54         };
  55
  56         //--------------------------------------------------------------------
  57         span_gradient() {}
  58
  59         //--------------------------------------------------------------------
  60         span_gradient(interpolator_type& inter,
  61                       const GradientF& gradient_function,
  62                       const ColorF& color_function,
  63                       double d1, double d2) :
  64             m_interpolator(&inter),
  65             m_gradient_function(&gradient_function),
  66             m_color_function(&color_function),
  67             m_d1(iround(d1 * gradient_subpixel_scale)),
  68             m_d2(iround(d2 * gradient_subpixel_scale))
  69         {}
  70
  71         //--------------------------------------------------------------------
  72         interpolator_type& interpolator() { return *m_interpolator; }
  73         const GradientF& gradient_function() const { return *m_gradient_function; }
  74         const ColorF& color_function() const { return *m_color_function; }
  75         double d1() const { return double(m_d1) / gradient_subpixel_scale; }
  76         double d2() const { return double(m_d2) / gradient_subpixel_scale; }
  77
  78         //--------------------------------------------------------------------
  79         void interpolator(interpolator_type& i) { m_interpolator = &i; }
  80         void gradient_function(const GradientF& gf) { m_gradient_function = &gf; }
  81         void color_function(const ColorF& cf) { m_color_function = &cf; }
  82         void d1(double v) { m_d1 = iround(v * gradient_subpixel_scale); }
  83         void d2(double v) { m_d2 = iround(v * gradient_subpixel_scale); }
  84
  85         //--------------------------------------------------------------------
  86         void prepare() {}
  87
  88         //--------------------------------------------------------------------
  89         void generate(color_type* span, int x, int y, unsigned len)
  90         {
  91             int dd = m_d2 - m_d1;
  92             if(dd < 1) dd = 1;
  93             m_interpolator->begin(x+0.5, y+0.5, len);
  94             do
  95             {
  96                 m_interpolator->coordinates(&x, &y);
  97                 int d = m_gradient_function->calculate(x >> downscale_shift,
  98                                                        y >> downscale_shift, m_d2);
  99                 d = ((d - m_d1) * (int)m_color_function->size()) / dd;
 100                 if(d < 0) d = 0;
 101                 if(d >= (int)m_color_function->size()) d = m_color_function->size() - 1;
 102                 *span++ = (*m_color_function)[d];
 103                 ++(*m_interpolator);
 104             }
 105             while(--len);
 106         }
 107
 108     private:
 109         interpolator_type* m_interpolator;
 110         const GradientF*   m_gradient_function;
 111         const ColorF*      m_color_function;
 112         int                m_d1;
 113         int                m_d2;
 114     };
 115
 116
 117
 118
 119     //=====================================================gradient_linear_color
 120     template<class ColorT>
 121     struct gradient_linear_color
 122     {
 123         typedef ColorT color_type;
 124
 125         gradient_linear_color() {}
 126         gradient_linear_color(const color_type& c1, const color_type& c2,
 127                               unsigned size = 256) :
 128             m_c1(c1), m_c2(c2), m_size(size) {}
 129
 130         unsigned size() const { return m_size; }
 131         color_type operator [] (unsigned v) const
 132         {
 133             return m_c1.gradient(m_c2, double(v) / double(m_size - 1));
 134         }
 135
 136         void colors(const color_type& c1, const color_type& c2, unsigned size = 256)
 137         {
 138             m_c1 = c1;
 139             m_c2 = c2;
 140             m_size = size;
 141         }
 142
 143         color_type m_c1;
 144         color_type m_c2;
 145         unsigned m_size;
 146     };
 147
 148
 149     //==========================================================gradient_circle
 150     class gradient_circle
 151     {
 152         // Actually the same as radial. Just for compatibility
 153     public:
 154         static AGG_INLINE int calculate(int x, int y, int)
 155         {
 156             return int(fast_sqrt(x*x + y*y));
 157         }
 158     };
 159
 160
 161     //==========================================================gradient_radial
 162     class gradient_radial
 163     {
 164     public:
 165         static AGG_INLINE int calculate(int x, int y, int)
 166         {
 167             return int(fast_sqrt(x*x + y*y));
 168         }
 169     };
 170
 171
 172     //========================================================gradient_radial_d
 173     class gradient_radial_d
 174     {
 175     public:
 176         static AGG_INLINE int calculate(int x, int y, int)
 177         {
 178             return uround(sqrt(double(x)*double(x) + double(y)*double(y)));
 179         }
 180     };
 181
 182
 183     //====================================================gradient_radial_focus
 184     class gradient_radial_focus
 185     {
 186     public:
 187         //---------------------------------------------------------------------
 188         gradient_radial_focus() :
 189             m_radius(100 * gradient_subpixel_scale),
 190             m_focus_x(0),
 191             m_focus_y(0)
 192         {
 193             update_values();
 194         }
 195
 196         //---------------------------------------------------------------------
 197         gradient_radial_focus(double r, double fx, double fy) :
 198             m_radius (iround(r  * gradient_subpixel_scale)),
 199             m_focus_x(iround(fx * gradient_subpixel_scale)),
 200             m_focus_y(iround(fy * gradient_subpixel_scale))
 201         {
 202             update_values();
 203         }
 204
 205         //---------------------------------------------------------------------
 206         void init(double r, double fx, double fy)
 207         {
 208             m_radius  = iround(r  * gradient_subpixel_scale);
 209             m_focus_x = iround(fx * gradient_subpixel_scale);
 210             m_focus_y = iround(fy * gradient_subpixel_scale);
 211             update_values();
 212         }
 213
 214         //---------------------------------------------------------------------
 215         double radius()  const { return double(m_radius)  / gradient_subpixel_scale; }
 216         double focus_x() const { return double(m_focus_x) / gradient_subpixel_scale; }
 217         double focus_y() const { return double(m_focus_y) / gradient_subpixel_scale; }
 218
 219         //---------------------------------------------------------------------
 220         int calculate(int x, int y, int) const
 221         {
 222             double solution_x;
 223             double solution_y;
 224
 225             // Special case to avoid divide by zero or very near zero
 226             //---------------------------------
 227             if(x == iround(m_focus_x))
 228             {
 229                 solution_x = m_focus_x;
 230                 solution_y = 0.0;
 231                 solution_y += (y > m_focus_y) ? m_trivial : -m_trivial;
 232             }
 233             else
 234             {
 235                 // Slope of the focus-current line
 236                 //-------------------------------
 237                 double slope = double(y - m_focus_y) / double(x - m_focus_x);
 238
 239                 // y-intercept of that same line
 240                 //--------------------------------
 241                 double yint  = double(y) - (slope * x);
 242
 243                 // Use the classical quadratic formula to calculate
 244                 // the intersection point
 245                 //--------------------------------
 246                 double a = (slope * slope) + 1;
 247                 double b =  2 * slope * yint;
 248                 double c =  yint * yint - m_radius2;
 249                 double det = sqrt((b * b) - (4.0 * a * c));
 250                         solution_x = -b;
 251
 252                 // Choose the positive or negative root depending
 253                 // on where the X coord lies with respect to the focus.
 254                 solution_x += (x < m_focus_x) ? -det : det;
 255                         solution_x /= 2.0 * a;
 256
 257                 // Calculating of Y is trivial
 258                 solution_y  = (slope * solution_x) + yint;
 259             }
 260
 261             // Calculate the percentage (0...1) of the current point along the
 262             // focus-circumference line and return the normalized (0...d) value
 263             //-------------------------------
 264             solution_x -= double(m_focus_x);
 265             solution_y -= double(m_focus_y);
 266             double int_to_focus = solution_x * solution_x + solution_y * solution_y;
 267             double cur_to_focus = double(x - m_focus_x) * double(x - m_focus_x) +
 268                                   double(y - m_focus_y) * double(y - m_focus_y);
 269
 270             return iround(sqrt(cur_to_focus / int_to_focus) * m_radius);
 271         }
 272
 273     private:
 274         //---------------------------------------------------------------------
 275         void update_values()
 276         {
 277             // For use in the quadratic equation
 278             //-------------------------------
 279             m_radius2 = double(m_radius) * double(m_radius);
 280
 281             double dist = sqrt(double(m_focus_x) * double(m_focus_x) +
 282                                double(m_focus_y) * double(m_focus_y));
 283
 284             // Test if distance from focus to center is greater than the radius
 285             // For the sake of assurance factor restrict the point to be
 286             // no further than 99% of the radius.
 287             //-------------------------------
 288             double r = m_radius * 0.99;
 289             if(dist > r)
 290             {
 291                 // clamp focus to radius
 292                 // x = r cos theta, y = r sin theta
 293                 //------------------------
 294                 double a = atan2(double(m_focus_y), double(m_focus_x));
 295                 m_focus_x = iround(r * cos(a));
 296                 m_focus_y = iround(r * sin(a));
 297             }
 298
 299             // Calculate the solution to be used in the case where x == focus_x
 300             //------------------------------
 301             m_trivial = sqrt(m_radius2 - (m_focus_x * m_focus_x));
 302         }
 303
 304         int m_radius;
 305         int m_focus_x;
 306         int m_focus_y;
 307         double m_radius2;
 308         double m_trivial;
 309     };
 310
 311
 312
 313     //==============================================================gradient_x
 314     class gradient_x
 315     {
 316     public:
 317         static int calculate(int x, int, int) { return x; }
 318     };
 319
 320
 321     //==============================================================gradient_y
 322     class gradient_y
 323     {
 324     public:
 325         static int calculate(int, int y, int) { return y; }
 326     };
 327
 328
 329     //========================================================gradient_diamond
 330     class gradient_diamond
 331     {
 332     public:
 333         static AGG_INLINE int calculate(int x, int y, int)
 334         {
 335             int ax = abs(x);
 336             int ay = abs(y);
 337             return ax > ay ? ax : ay;
 338         }
 339     };
 340
 341
 342     //=============================================================gradient_xy
 343     class gradient_xy
 344     {
 345     public:
 346         static AGG_INLINE int calculate(int x, int y, int d)
 347         {
 348             return abs(x) * abs(y) / d;
 349         }
 350     };
 351
 352
 353     //========================================================gradient_sqrt_xy
 354     class gradient_sqrt_xy
 355     {
 356     public:
 357         static AGG_INLINE int calculate(int x, int y, int)
 358         {
 359             return fast_sqrt(abs(x) * abs(y));
 360         }
 361     };
 362
 363
 364     //==========================================================gradient_conic
 365     class gradient_conic
 366     {
 367     public:
 368         static AGG_INLINE int calculate(int x, int y, int d)
 369         {
 370             return uround(fabs(atan2(double(y), double(x))) * double(d) / pi);
 371         }
 372     };
 373
 374
 375     //=================================================gradient_repeat_adaptor
 376     template<class GradientF> class gradient_repeat_adaptor
 377     {
 378     public:
 379         gradient_repeat_adaptor(const GradientF& gradient) :
 380             m_gradient(&gradient) {}
 381
 382         AGG_INLINE int calculate(int x, int y, int d) const
 383         {
 384             int ret = m_gradient->calculate(x, y, d) % d;
 385             if(ret < 0) ret += d;
 386             return ret;
 387         }
 388
 389     private:
 390         const GradientF* m_gradient;
 391     };
 392
 393
 394     //================================================gradient_reflect_adaptor
 395     template<class GradientF> class gradient_reflect_adaptor
 396     {
 397     public:
 398         gradient_reflect_adaptor(const GradientF& gradient) :
 399             m_gradient(&gradient) {}
 400
 401         AGG_INLINE int calculate(int x, int y, int d) const
 402         {
 403             int d2 = d << 1;
 404             int ret = m_gradient->calculate(x, y, d) % d2;
 405             if(ret <  0) ret += d2;
 406             if(ret >= d) ret  = d2 - ret;
 407             return ret;
 408         }
 409
 410     private:
 411         const GradientF* m_gradient;
 412     };
 413
 414
 415 }
 416
 417 #endif