synfig-core/trunk/src/synfig/gradient.cpp

   1 /* === S Y N F I G ========================================================= */
   2 /*!     \file gradient.cpp
   3 **      \brief Color Gradient Class Member Definitions
   4 **
   5 **      $Id$
   6 **
   7 **      \legal
   8 **      Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
   9 **
  10 **      This package is free software; you can redistribute it and/or
  11 **      modify it under the terms of the GNU General Public License as
  12 **      published by the Free Software Foundation; either version 2 of
  13 **      the License, or (at your option) any later version.
  14 **
  15 **      This package is distributed in the hope that it will be useful,
  16 **      but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 **      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18 **      General Public License for more details.
  19 **      \endlegal
  20 */
  21 /* ========================================================================= */
  22
  23 /* === H E A D E R S ======================================================= */
  24
  25 #ifdef USING_PCH
  26 #       include "pch.h"
  27 #else
  28 #ifdef HAVE_CONFIG_H
  29 #       include <config.h>
  30 #endif
  31
  32 #include "gradient.h"
  33 #include "general.h"
  34 #include <stdexcept>
  35 #include "exception.h"
  36
  37 #include <ETL/misc>
  38 #endif
  39
  40 /* === U S I N G =========================================================== */
  41
  42 using namespace std;
  43 using namespace etl;
  44 using namespace synfig;
  45
  46 /* === M A C R O S ========================================================= */
  47
  48 /* === G L O B A L S ======================================================= */
  49
  50 /* === P R O C E D U R E S ================================================= */
  51
  52 /* === M E T H O D S ======================================================= */
  53
  54 synfig::Gradient::Gradient(const Color &c1, const Color &c2)
  55 {
  56         push_back(CPoint(0.0,c1));
  57         push_back(CPoint(1.0,c2));
  58 }
  59
  60 synfig::Gradient::Gradient(const Color &c1, const Color &c2, const Color &c3)
  61 {
  62         push_back(CPoint(0.0,c1));
  63         push_back(CPoint(0.5,c2));
  64         push_back(CPoint(1.0,c3));
  65 }
  66
  67 // This sort algorithm MUST be stable
  68 // ie: it must not change the order of items with the same value.
  69 // I am using a bubble sort.
  70 // This algorithm will sort a nearly-sorted list at ~O(N), and
  71 // it will sort an inverse sorted list at ~O(N*N).
  72 void
  73 synfig::Gradient::sort()
  74 {
  75         stable_sort(begin(),end());
  76         /*
  77         iterator iter;
  78         iterator iter2,next;
  79
  80         for(iter=begin();iter!=end();iter++)
  81         {
  82                 for(next=iter, iter2=next--;iter2!=begin();iter2=next--)
  83                 {
  84                         if(*iter<*next)
  85                         {
  86                                 //insert(next,*iter);
  87                                 //erase(iter);
  88                                 iter_swap(next,iter);
  89
  90                                 continue;
  91                         }
  92                         else
  93                                 break;
  94                 }
  95         }
  96         */
  97 }
  98
  99 static synfig::ColorAccumulator
 100 supersample_helper(const synfig::Gradient::CPoint &color1, const synfig::Gradient::CPoint &color2, float begin, float end, float &weight)
 101 {
 102         if(color1.pos==color2.pos || color1.pos>=end || color2.pos<=begin)
 103         {
 104                 weight=0;
 105                 return Color::alpha();
 106         }
 107         if(color1.pos>=begin && color2.pos<end)
 108         {
 109                 weight=color2.pos-color1.pos;
 110                 ColorAccumulator ret=Color::blend(color2.color,color1.color, 0.5, Color::BLEND_STRAIGHT).premult_alpha()*weight;
 111                 return ret;
 112         }
 113         if(color1.pos>=begin && color2.pos>=end)
 114         {
 115                 weight=end-color1.pos;
 116                 float pos((end+color1.pos)*0.5);
 117                 float amount((pos-color1.pos)/(color2.pos-color1.pos));
 118                 //if(abs(amount)>1)amount=(amount>0)?1:-1;
 119                 ColorAccumulator ret(Color::blend(color2.color,color1.color, amount, Color::BLEND_STRAIGHT).premult_alpha()*weight);
 120                 return ret;
 121         }
 122         if(color1.pos<begin && color2.pos<end)
 123         {
 124                 weight=color2.pos-begin;
 125                 float pos((begin+color2.pos)*0.5);
 126                 float amount((pos-color1.pos)/(color2.pos-color1.pos));
 127                 //if(abs(amount)>1)amount=(amount>0)?1:-1;
 128                 ColorAccumulator ret(Color::blend(color2.color,color1.color, amount, Color::BLEND_STRAIGHT).premult_alpha()*weight);
 129                 return ret;
 130         }
 131         synfig::error("color1.pos=%f",color1.pos);
 132         synfig::error("color2.pos=%f",color2.pos);
 133         synfig::error("begin=%f",begin);
 134         synfig::error("end=%f",end);
 135
 136         weight=0;
 137         return Color::alpha();
 138
 139 //      assert(0);
 140 }
 141
 142 Color
 143 synfig::Gradient::operator()(const Real &x,float supersample)const
 144 {
 145         if(empty())
 146                 return Color(0,0,0,0);
 147         if(supersample<0)
 148                 supersample=-supersample;
 149         if(supersample>2.0)
 150                 supersample=2.0f;
 151
 152         float begin_sample(x-supersample*0.5);
 153         float end_sample(x+supersample*0.5);
 154
 155         if(size()==1 || end_sample<=front().pos || isnan(x))
 156                 return front().color;
 157
 158         if(begin_sample>=back().pos)
 159                 return back().color;
 160
 161         /*
 162         if(end_sample>=back().pos)
 163                 end_sample=back().pos;
 164
 165         if(begin_sample<=front().pos)
 166                 begin_sample=front().pos;
 167         */
 168
 169         const_iterator iter,next;
 170
 171         /*
 172         //optimizize...
 173         Real    left = x-supersample/2, right = x+supersample/2;
 174
 175         if(left < front().pos) left = front().pos;
 176         if(right > back().pos) right = back().pos;
 177
 178         //find using binary search...
 179         const_iterator iterl,iterr;
 180
 181         //the binary search should give us the values BEFORE the point we're looking for...
 182         iterl = binary_find(begin(),end(),left);
 183         iterr = binary_find(iterl,end(),right);
 184
 185         //now integrate over the range of left to right...
 186
 187         if(iterl == iterr)
 188         {
 189                 iterr++; //let's look at the next one shall we :)
 190
 191                 //interpolate neighboring colors
 192                 const Real one = iterr->pos - iterl->pos;
 193                 const Real lambda = (x - iterl->pos)/one;
 194
 195                 //(1-l)iterl + (l)iterr
 196                 return iterl->color.premult_alpha()*(1-lambda) + iterr->color.premult_alpha()*lambda;
 197
 198                 //return Color::blend(iterr->color,iterl->color,lambda,Color::BLEND_STRAIGHT);
 199         }else
 200         {
 201                 //itegration madness
 202                 const_iterator i = iterl, ie = iterr+1;
 203                 Real wlast = left;
 204
 205                 ColorAccumulator clast,cwork;
 206                 {
 207                         const Real lambda = (x - iterl->pos)/(iterr->pos - iterl->pos);
 208
 209                         //premultiply because that's the form in which we can combine things...
 210                         clast = iterl->color.premult_alpha()*(1-lambda) + iterr->color.premult_alpha()*lambda;
 211                         //Color::blend((i+1)->color,i->color,(left - i->pos)/((i+1)->pos - i->pos),Color::BLEND_STRAIGHT);
 212                 }
 213
 214                 ColorAccumulator        accum = 0;
 215
 216                 //loop through all the trapezoids and integrate them as we go...
 217                 //      area of trap = (yi + yi1)*(xi1 - xi)
 218                 //      yi = clast, xi = wlast, yi1 = i->color, xi1 = i->pos
 219
 220                 for(;i<=iterr; wlast=i->pos,clast=i->color.premult_alpha(),++i)
 221                 {
 222                         const Real diff = i->pos - wlast;
 223                         if(diff > 0) //only accumulate if there will be area to add
 224                         {
 225                                 cwork = i->color.premult_alpha();
 226                                 accum += (cwork + clast)*diff;
 227                         }
 228                 }
 229
 230                 {
 231                         const_iterator ibef = i-1;
 232                         const Real diff = right - ibef->pos;
 233
 234                         if(diff > 0)
 235                         {
 236                                 const Real lambda = diff/(i->pos - ibef->pos);
 237                                 cwork = ibef->color.premult_alpha()*(1-lambda) + i->color.premult_alpha()*lambda;
 238
 239                                 accum += (cwork + clast)*diff; //can probably optimize this more... but it's not too bad
 240                         }
 241                 }
 242
 243                 accum /= supersample; //should be the total area it was sampled over...
 244                 return accum.demult_alpha();
 245         }*/
 246
 247         next=begin(),iter=next++;
 248
 249         //add for optimization
 250         next = binary_find(begin(),end(),(Real)begin_sample);
 251         iter = next++;
 252
 253         //! As a future optimization, this could be performed faster
 254         //! using a binary search.
 255         for(;iter<end();iter=next++)
 256         {
 257                 if(next==end() || x>=iter->pos &&  x<next->pos && iter->pos!=next->pos)
 258                 {
 259                         // If the supersample region falls square in between
 260                         // two CPoints, then we don't have to do anything special.
 261                         if(next!=end() && (!supersample || (iter->pos<=begin_sample && next->pos>=end_sample)))
 262                         {
 263                                 const Real dist(next->pos-iter->pos);
 264                                 const Real pos(x-iter->pos);
 265                                 const Real amount(pos/dist);
 266                                 return Color::blend(next->color,iter->color, amount, Color::BLEND_STRAIGHT);
 267                         }
 268                         // In this case our supersample region extends over one or more
 269                         // CPoints. So, we need to calculate our coverage amount.
 270                         ColorAccumulator pool(Color::alpha());
 271                         float divisor(0.0),weight(0);
 272
 273                         const_iterator iter2,next2;
 274                         iter2=iter;
 275                         if(iter==begin() && iter->pos>x)
 276                         {
 277                                 weight=x-iter->pos;
 278                                 //weight*=iter->color.get_a();
 279                                 pool+=ColorAccumulator(iter->color).premult_alpha()*weight;
 280                                 divisor+=weight;
 281                         }
 282                         else
 283                         {
 284                                 while(iter2->pos>=begin_sample)
 285                                 {
 286                                         if(iter2==begin())
 287                                         {
 288                                                 weight=iter2->pos-(begin_sample);
 289                                                 //weight*=iter2->color.get_a();
 290                                                 pool+=ColorAccumulator(iter2->color).premult_alpha()*weight;
 291                                                 divisor+=weight;
 292                                                 break;
 293                                         }
 294                                         next2=iter2--;
 295                                         pool+=supersample_helper(*iter2, *next2, begin_sample, end_sample, weight);
 296                                         divisor+=weight;
 297                                 }
 298                         }
 299
 300                         next2=iter;
 301                         iter2=next2++;
 302                         while(iter2->pos<=end_sample)
 303                         {
 304                                 if(next2==end())
 305                                 {
 306                                         weight=(end_sample)-iter2->pos;
 307                                         pool+=ColorAccumulator(iter2->color).premult_alpha()*weight;
 308                                         divisor+=weight;
 309                                         break;
 310                                 }
 311                                 pool+=supersample_helper(*iter2, *next2, begin_sample, end_sample, weight);
 312                                 divisor+=weight;
 313                                 iter2=next2++;
 314                         }
 315
 316                         if(divisor && pool.get_a() && pool.is_valid())
 317                         {
 318 /*
 319                                 pool.set_r(pool.get_r()/pool.get_a());
 320                                 pool.set_g(pool.get_g()/pool.get_a());
 321                                 pool.set_b(pool.get_b()/pool.get_a());
 322                                 pool.set_a(pool.get_a()/divisor);
 323 */
 324                                 pool/=divisor;
 325                                 pool.set_r(pool.get_r()/pool.get_a());
 326                                 pool.set_g(pool.get_g()/pool.get_a());
 327                                 pool.set_b(pool.get_b()/pool.get_a());
 328                                 if(pool.is_valid())
 329                                         return pool;
 330                                 else
 331                                         return Color::alpha();
 332                         }
 333                         else
 334                                 return Color::alpha();
 335                 }
 336         }
 337
 338         // We should never get to this point.
 339
 340         synfig::error("synfig::Gradient::operator()(): Logic Error (x=%f)",x);
 341         assert(0);
 342         throw std::logic_error(strprintf("synfig::Gradient::operator()(): Logic Error (x=%f)",x));
 343 }
 344
 345 synfig::Gradient::iterator
 346 synfig::Gradient::proximity(const Real &x)
 347 {
 348         iterator iter;
 349         float dist(100000000);
 350         float prev_pos(-0230);
 351         // This algorithm requires a sorted list.
 352         for(iter=begin();iter<end();iter++)
 353         {
 354                 float new_dist;
 355
 356                 if(prev_pos==iter->pos)
 357                         new_dist=(abs(x-iter->pos-0.00001));
 358                 else
 359                         new_dist=(abs(x-iter->pos));
 360
 361                 if(new_dist>dist)
 362                 {
 363                         iter--;
 364                         return iter;
 365                 }
 366                 dist=new_dist;
 367                 prev_pos=iter->pos;
 368         }
 369         iter--;
 370         return iter;
 371 }
 372
 373 synfig::Gradient::const_iterator
 374 synfig::Gradient::proximity(const Real &x)const
 375 {
 376         return const_cast<Gradient*>(this)->proximity(x);
 377         /*
 378         const_iterator iter;
 379         float dist(100000000);
 380
 381         // This algorithm requires a sorted list.
 382         for(iter=begin();iter<end();iter++)
 383         {
 384                 const float new_dist(abs(x-iter->pos));
 385                 if(new_dist>dist)
 386                 {
 387                         iter--;
 388                         return iter;
 389                 }
 390                 dist=new_dist;
 391         }
 392         iter--;
 393         return iter;
 394         */
 395 }
 396
 397 synfig::Gradient::iterator
 398 synfig::Gradient::find(const UniqueID &id)
 399 {
 400         iterator iter;
 401
 402         for(iter=begin();iter<end();iter++)
 403         {
 404                 if(id==*iter)
 405                         return iter;
 406         }
 407
 408         throw Exception::NotFound("synfig::Gradient::find(): Unable to find UniqueID in gradient");
 409 }
 410
 411 synfig::Gradient::const_iterator
 412 synfig::Gradient::find(const UniqueID &id)const
 413 {
 414         const_iterator iter;
 415
 416         for(iter=begin();iter<end();iter++)
 417         {
 418                 if(id==*iter)
 419                         return iter;
 420         }
 421
 422         throw Exception::NotFound("synfig::Gradient::find()const: Unable to find UniqueID in gradient");
 423 }