agg/inc/agg_span_gradient.h

   1 //----------------------------------------------------------------------------
   2 // Anti-Grain Geometry - Version 2.3
   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_span_generator.h"
  24 #include "agg_math.h"
  25 #include "agg_array.h"
  26
  27
  28 namespace agg
  29 {
  30
  31     enum
  32     {
  33         gradient_subpixel_shift = 4,                              //-----gradient_subpixel_shift
  34         gradient_subpixel_size  = 1 << gradient_subpixel_shift,   //-----gradient_subpixel_size
  35         gradient_subpixel_mask  = gradient_subpixel_size - 1      //-----gradient_subpixel_mask
  36     };
  37
  38
  39
  40     //==========================================================span_gradient
  41     template<class ColorT,
  42              class Interpolator,
  43              class GradientF,
  44              class ColorF,
  45              class Allocator = span_allocator<ColorT> >
  46     class span_gradient : public span_generator<ColorT, Allocator>
  47     {
  48     public:
  49         typedef Interpolator interpolator_type;
  50         typedef Allocator alloc_type;
  51         typedef ColorT color_type;
  52         typedef span_generator<color_type, alloc_type> base_type;
  53
  54         enum
  55         {
  56             downscale_shift = interpolator_type::subpixel_shift -
  57                               gradient_subpixel_shift
  58         };
  59
  60         //--------------------------------------------------------------------
  61         span_gradient(alloc_type& alloc) : base_type(alloc) {}
  62
  63         //--------------------------------------------------------------------
  64         span_gradient(alloc_type& alloc,
  65                       interpolator_type& inter,
  66                       const GradientF& gradient_function_,
  67                       const ColorF& color_function_,
  68                       double d1_, double d2_) :
  69             base_type(alloc),
  70             m_interpolator(&inter),
  71             m_gradient_function(&gradient_function_),
  72             m_color_function(&color_function_),
  73             m_d1(int(d1_ * gradient_subpixel_size)),
  74             m_d2(int(d2_ * gradient_subpixel_size))
  75         {}
  76
  77         //--------------------------------------------------------------------
  78         interpolator_type& interpolator() { return *m_interpolator; }
  79         const GradientF& gradient_function() const { return *m_gradient_function; }
  80         const ColorF& color_function() const { return *m_color_function; }
  81         double d1() const { return double(m_d1) / gradient_subpixel_size; }
  82         double d2() const { return double(m_d2) / gradient_subpixel_size; }
  83
  84         //--------------------------------------------------------------------
  85         void interpolator(interpolator_type& i) { m_interpolator = &i; }
  86         void gradient_function(const GradientF& gf) { m_gradient_function = &gf; }
  87         void color_function(const ColorF& cf) { m_color_function = &cf; }
  88         void d1(double v) { m_d1 = int(v * gradient_subpixel_size); }
  89         void d2(double v) { m_d2 = int(v * gradient_subpixel_size); }
  90
  91         //--------------------------------------------------------------------
  92         color_type* generate(int x, int y, unsigned len)
  93         {
  94             color_type* span = base_type::allocator().span();
  95             int dd = m_d2 - m_d1;
  96             if(dd < 1) dd = 1;
  97             m_interpolator->begin(x+0.5, y+0.5, len);
  98             do
  99             {
 100                 m_interpolator->coordinates(&x, &y);
 101                 int d = m_gradient_function->calculate(x >> downscale_shift,
 102                                                        y >> downscale_shift, dd);
 103                 d = ((d - m_d1) * (int)m_color_function->size()) / dd;
 104                 if(d < 0) d = 0;
 105                 if(d >= (int)m_color_function->size()) d = m_color_function->size() - 1;
 106                 *span++ = (*m_color_function)[d];
 107                 ++(*m_interpolator);
 108             }
 109             while(--len);
 110             return base_type::allocator().span();
 111         }
 112
 113     private:
 114         interpolator_type* m_interpolator;
 115         const GradientF*   m_gradient_function;
 116         const ColorF*      m_color_function;
 117         int                m_d1;
 118         int                m_d2;
 119     };
 120
 121
 122
 123
 124     //=====================================================gradient_linear_color
 125     template<class ColorT>
 126     struct gradient_linear_color
 127     {
 128         typedef ColorT color_type;
 129
 130         gradient_linear_color() {}
 131         gradient_linear_color(const color_type& c1, const color_type& c2,
 132                               unsigned size = 256) :
 133             m_c1(c1), m_c2(c2), m_size(size) {}
 134
 135         unsigned size() const { return m_size; }
 136         color_type operator [] (unsigned v) const
 137         {
 138             return m_c1.gradient(m_c2, double(v) / double(m_size - 1));
 139         }
 140
 141         void colors(const color_type& c1, const color_type& c2, unsigned size = 256)
 142         {
 143             m_c1 = c1;
 144             m_c2 = c2;
 145             m_size = size;
 146         }
 147
 148         color_type m_c1;
 149         color_type m_c2;
 150         unsigned m_size;
 151     };
 152
 153
 154     //==========================================================gradient_circle
 155     class gradient_circle
 156     {
 157         // Actually the same as radial. Just for compatibility
 158     public:
 159         static AGG_INLINE int calculate(int x, int y, int)
 160         {
 161             return int(fast_sqrt(x*x + y*y));
 162         }
 163     };
 164
 165
 166     //==========================================================gradient_radial
 167     class gradient_radial
 168     {
 169     public:
 170         static AGG_INLINE int calculate(int x, int y, int)
 171         {
 172             return int(fast_sqrt(x*x + y*y));
 173         }
 174     };
 175
 176
 177     //========================================================gradient_radial_d
 178     class gradient_radial_d
 179     {
 180     public:
 181         static AGG_INLINE int calculate(int x, int y, int)
 182         {
 183             return int(sqrt(double(x)*double(x) + double(y)*double(y)));
 184         }
 185     };
 186
 187
 188     //====================================================gradient_radial_focus
 189     class gradient_radial_focus
 190     {
 191     public:
 192         //---------------------------------------------------------------------
 193         gradient_radial_focus() :
 194             m_radius(100 * gradient_subpixel_size),
 195             m_focus_x(0),
 196             m_focus_y(0)
 197         {
 198             update_values();
 199         }
 200
 201         //---------------------------------------------------------------------
 202         gradient_radial_focus(double r, double fx, double fy) :
 203             m_radius (int(r  * gradient_subpixel_size)),
 204             m_focus_x(int(fx * gradient_subpixel_size)),
 205             m_focus_y(int(fy * gradient_subpixel_size))
 206         {
 207             update_values();
 208         }
 209
 210         //---------------------------------------------------------------------
 211         void init(double r, double fx, double fy)
 212         {
 213             m_radius  = int(r  * gradient_subpixel_size);
 214             m_focus_x = int(fx * gradient_subpixel_size);
 215             m_focus_y = int(fy * gradient_subpixel_size);
 216             update_values();
 217         }
 218
 219         //---------------------------------------------------------------------
 220         double radius()  const { return double(m_radius)  / gradient_subpixel_size; }
 221         double focus_x() const { return double(m_focus_x) / gradient_subpixel_size; }
 222         double focus_y() const { return double(m_focus_y) / gradient_subpixel_size; }
 223
 224         //---------------------------------------------------------------------
 225         int calculate(int x, int y, int d) const
 226         {
 227             double solution_x;
 228             double solution_y;
 229
 230             // Special case to avoid divide by zero or very near zero
 231             //---------------------------------
 232             if(x == int(m_focus_x))
 233             {
 234                 solution_x = m_focus_x;
 235                 solution_y = 0.0;
 236                 solution_y += (y > m_focus_y) ? m_trivial : -m_trivial;
 237             }
 238             else
 239             {
 240                 // Slope of the focus-current line
 241                 //-------------------------------
 242                 double slope = double(y - m_focus_y) / double(x - m_focus_x);
 243
 244                 // y-intercept of that same line
 245                 //--------------------------------
 246                 double yint  = double(y) - (slope * x);
 247
 248                 // Use the classical quadratic formula to calculate
 249                 // the intersection point
 250                 //--------------------------------
 251                 double a = (slope * slope) + 1;
 252                 double b =  2 * slope * yint;
 253                 double c =  yint * yint - m_radius2;
 254                 double det = sqrt((b * b) - (4.0 * a * c));
 255                 solution_x = -b;
 256
 257                 // Choose the positive or negative root depending
 258                 // on where the X coord lies with respect to the focus.
 259                 solution_x += (x < m_focus_x) ? -det : det;
 260                 solution_x /= 2.0 * a;
 261
 262                 // Calculating of Y is trivial
 263                 solution_y  = (slope * solution_x) + yint;
 264             }
 265
 266             // Calculate the percentage (0...1) of the current point along the
 267             // focus-circumference line and return the normalized (0...d) value
 268             //-------------------------------
 269             solution_x -= double(m_focus_x);
 270             solution_y -= double(m_focus_y);
 271             double int_to_focus = solution_x * solution_x + solution_y * solution_y;
 272             double cur_to_focus = double(x - m_focus_x) * double(x - m_focus_x) +
 273                                   double(y - m_focus_y) * double(y - m_focus_y);
 274
 275             return int(sqrt(cur_to_focus / int_to_focus) * d);
 276         }
 277
 278     private:
 279         //---------------------------------------------------------------------
 280         void update_values()
 281         {
 282             // For use in the quadractic equation
 283             //-------------------------------
 284             m_radius2 = double(m_radius) * double(m_radius);
 285
 286             double dist = sqrt(double(m_focus_x) * double(m_focus_x) +
 287                                double(m_focus_y) * double(m_focus_y));
 288
 289             // Test if distance from focus to center is greater than the radius
 290             // For the sake of assurance factor restrict the point to be
 291             // no further than 99% of the radius.
 292             //-------------------------------
 293             double r = m_radius * 0.99;
 294             if(dist > r)
 295             {
 296                 // clamp focus to radius
 297                 // x = r cos theta, y = r sin theta
 298                 //------------------------
 299                 double a = atan2(double(m_focus_y), double(m_focus_x));
 300                 m_focus_x = int(r * cos(a));
 301                 m_focus_y = int(r * sin(a));
 302             }
 303
 304             // Calculate the solution to be used in the case where x == focus_x
 305             //------------------------------
 306             m_trivial = sqrt(m_radius2 - (m_focus_x * m_focus_x));
 307         }
 308
 309         int m_radius;
 310         int m_focus_x;
 311         int m_focus_y;
 312         double m_radius2;
 313         double m_trivial;
 314     };
 315
 316
 317
 318     //==============================================================gradient_x
 319     class gradient_x
 320     {
 321     public:
 322         static int calculate(int x, int, int) { return x; }
 323     };
 324
 325
 326     //==============================================================gradient_y
 327     class gradient_y
 328     {
 329     public:
 330         static int calculate(int, int y, int) { return y; }
 331     };
 332
 333
 334     //========================================================gradient_diamond
 335     class gradient_diamond
 336     {
 337     public:
 338         static AGG_INLINE int calculate(int x, int y, int)
 339         {
 340             int ax = abs(x);
 341             int ay = abs(y);
 342             return ax > ay ? ax : ay;
 343         }
 344     };
 345
 346
 347     //=============================================================gradient_xy
 348     class gradient_xy
 349     {
 350     public:
 351         static AGG_INLINE int calculate(int x, int y, int d)
 352         {
 353             return abs(x) * abs(y) / d;
 354         }
 355     };
 356
 357
 358     //========================================================gradient_sqrt_xy
 359     class gradient_sqrt_xy
 360     {
 361     public:
 362         static AGG_INLINE int calculate(int x, int y, int)
 363         {
 364             return fast_sqrt(abs(x) * abs(y));
 365         }
 366     };
 367
 368
 369     //==========================================================gradient_conic
 370     class gradient_conic
 371     {
 372     public:
 373         static AGG_INLINE int calculate(int x, int y, int d)
 374         {
 375             return int(fabs(atan2(double(y), double(x))) * double(d) / pi);
 376         }
 377     };
 378
 379
 380     //=================================================gradient_repeat_adaptor
 381     template<class GradientF> class gradient_repeat_adaptor
 382     {
 383     public:
 384         gradient_repeat_adaptor(const GradientF& gradient) :
 385             m_gradient(&gradient) {}
 386
 387         AGG_INLINE int calculate(int x, int y, int d) const
 388         {
 389             int ret = m_gradient->calculate(x, y, d) % d;
 390             if(ret < 0) ret += d;
 391             return ret;
 392         }
 393
 394     private:
 395         const GradientF* m_gradient;
 396     };
 397
 398
 399     //================================================gradient_reflect_adaptor
 400     template<class GradientF> class gradient_reflect_adaptor
 401     {
 402     public:
 403         gradient_reflect_adaptor(const GradientF& gradient) :
 404             m_gradient(&gradient) {}
 405
 406         AGG_INLINE int calculate(int x, int y, int d) const
 407         {
 408             int d2 = d << 1;
 409             int ret = m_gradient->calculate(x, y, d) % d2;
 410             if(ret <  0) ret += d2;
 411             if(ret >= d) ret  = d2 - ret;
 412             return ret;
 413         }
 414
 415     private:
 416         const GradientF* m_gradient;
 417     };
 418
 419
 420 }
 421
 422 #endif