cinelerra-5.1/plugins/threshold/threshold.C

   1
   2 /*
   3  * CINELERRA
   4  * Copyright (C) 2008 Adam Williams <broadcast at earthling dot net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  */
  21
  22 #include <string>
  23 #include <string.h>
  24
  25 #include "threshold.h"
  26 #include "bccolors.h"
  27 #include "clip.h"
  28 #include "bchash.h"
  29 #include "filexml.h"
  30 #include "histogramengine.h"
  31 #include "language.h"
  32 #include "playback3d.h"
  33 #include "thresholdwindow.h"
  34 #include "vframe.h"
  35
  36 using ::std::string;
  37
  38
  39
  40 ThresholdConfig::ThresholdConfig()
  41 {
  42         reset();
  43 }
  44
  45 int ThresholdConfig::equivalent(ThresholdConfig &that)
  46 {
  47         return EQUIV(min, that.min) &&
  48                 EQUIV(max, that.max) &&
  49                 plot == that.plot &&
  50                 low_color == that.low_color &&
  51                 mid_color == that.mid_color &&
  52                 high_color == that.high_color;
  53 }
  54
  55 void ThresholdConfig::copy_from(ThresholdConfig &that)
  56 {
  57         min = that.min;
  58         max = that.max;
  59         plot = that.plot;
  60         low_color = that.low_color;
  61         mid_color = that.mid_color;
  62         high_color = that.high_color;
  63 }
  64
  65 // General purpose scale function.
  66 template<typename T>
  67 T interpolate(const T & prev, const double & prev_scale, const T & next, const double & next_scale)
  68 {
  69         return static_cast<T>(prev * prev_scale + next * next_scale);
  70 }
  71
  72 void ThresholdConfig::interpolate(ThresholdConfig &prev,
  73         ThresholdConfig &next,
  74         int64_t prev_frame,
  75         int64_t next_frame,
  76         int64_t current_frame)
  77 {
  78         double next_scale = (double)(current_frame - prev_frame) /
  79                 (next_frame - prev_frame);
  80         double prev_scale = (double)(next_frame - current_frame) /
  81                 (next_frame - prev_frame);
  82
  83         min = ::interpolate(prev.min, prev_scale, next.min, next_scale);
  84         max = ::interpolate(prev.max, prev_scale, next.max, next_scale);
  85         plot = prev.plot;
  86
  87         low_color =  ::interpolate(prev.low_color,  prev_scale, next.low_color,  next_scale);
  88         mid_color =  ::interpolate(prev.mid_color,  prev_scale, next.mid_color,  next_scale);
  89         high_color = ::interpolate(prev.high_color, prev_scale, next.high_color, next_scale);
  90 }
  91
  92 void ThresholdConfig::reset()
  93 {
  94         min = 0.0;
  95         max = 1.0;
  96         plot = 1;
  97         low_color.set (0x0,  0x0,  0x0,  0xff);
  98         mid_color.set (0xff, 0xff, 0xff, 0xff);
  99         high_color.set(0x0,  0x0,  0x0,  0xff);
 100 }
 101
 102 void ThresholdConfig::boundaries()
 103 {
 104         CLAMP(min, HISTOGRAM_MIN, max);
 105         CLAMP(max, min, HISTOGRAM_MAX);
 106 }
 107
 108
 109
 110
 111
 112
 113
 114
 115 REGISTER_PLUGIN(ThresholdMain)
 116
 117 ThresholdMain::ThresholdMain(PluginServer *server)
 118  : PluginVClient(server)
 119 {
 120         engine = 0;
 121         threshold_engine = 0;
 122 }
 123
 124 ThresholdMain::~ThresholdMain()
 125 {
 126         delete engine;
 127         delete threshold_engine;
 128 }
 129
 130 const char* ThresholdMain::plugin_title() { return N_("Threshold"); }
 131 int ThresholdMain::is_realtime() { return 1; }
 132
 133
 134
 135 LOAD_CONFIGURATION_MACRO(ThresholdMain, ThresholdConfig)
 136
 137
 138
 139
 140
 141
 142
 143 int ThresholdMain::process_buffer(VFrame *frame,
 144         int64_t start_position,
 145         double frame_rate)
 146 {
 147         load_configuration();
 148
 149         int use_opengl = get_use_opengl() &&
 150                 (!config.plot || !gui_open());
 151
 152         read_frame(frame,
 153                 0,
 154                 get_source_position(),
 155                 get_framerate(),
 156                 use_opengl);
 157
 158         send_render_gui(frame);
 159
 160         if(use_opengl) return run_opengl();
 161
 162         if(!threshold_engine)
 163                 threshold_engine = new ThresholdEngine(this);
 164         threshold_engine->process_packages(frame);
 165
 166         return 0;
 167 }
 168
 169 void ThresholdMain::save_data(KeyFrame *keyframe)
 170 {
 171         FileXML output;
 172         output.set_shared_output(keyframe->xbuf);
 173         output.tag.set_title("THRESHOLD");
 174         output.tag.set_property("MIN", config.min);
 175         output.tag.set_property("MAX", config.max);
 176         output.tag.set_property("PLOT", config.plot);
 177         config.low_color.set_property(output.tag,  "LOW_COLOR");
 178         config.mid_color.set_property(output.tag,  "MID_COLOR");
 179         config.high_color.set_property(output.tag, "HIGH_COLOR");
 180         output.append_tag();
 181         output.tag.set_title("/THRESHOLD");
 182         output.append_tag();
 183         output.append_newline();
 184         output.terminate_string();
 185 }
 186
 187 void ThresholdMain::read_data(KeyFrame *keyframe)
 188 {
 189         FileXML input;
 190         input.set_shared_input(keyframe->xbuf);
 191         int result = 0;
 192         while(!result)
 193         {
 194                 result = input.read_tag();
 195                 if(!result)
 196                 {
 197                         config.min = input.tag.get_property("MIN", config.min);
 198                         config.max = input.tag.get_property("MAX", config.max);
 199                         config.plot = input.tag.get_property("PLOT", config.plot);
 200                         config.low_color = config.low_color.get_property(input.tag, "LOW_COLOR");
 201                         config.mid_color = config.mid_color.get_property(input.tag, "MID_COLOR");
 202                         config.high_color = config.high_color.get_property(input.tag, "HIGH_COLOR");
 203                 }
 204         }
 205         config.boundaries();
 206 }
 207
 208 NEW_WINDOW_MACRO(ThresholdMain,ThresholdWindow);
 209
 210 void ThresholdMain::update_gui()
 211 {
 212         if(thread)
 213         {
 214                 thread->window->lock_window("ThresholdMain::update_gui");
 215                 if(load_configuration())
 216                 {
 217                         ThresholdWindow *window = (ThresholdWindow*) thread->window;
 218                         window->min->update(config.min);
 219                         window->max->update(config.max);
 220                         window->plot->update(config.plot);
 221                         window->update_low_color();
 222                         window->update_mid_color();
 223                         window->update_high_color();
 224                         window->low_color_thread->update_gui(config.low_color.getRGB(), config.low_color.a);
 225                         window->mid_color_thread->update_gui(config.mid_color.getRGB(), config.mid_color.a);
 226                         window->high_color_thread->update_gui(config.high_color.getRGB(), config.high_color.a);
 227                 }
 228                 thread->window->unlock_window();
 229         }
 230 }
 231
 232 void ThresholdMain::render_gui(void *data)
 233 {
 234         if(thread)
 235         {
 236                 calculate_histogram((VFrame*)data);
 237                 ThresholdWindow *window = (ThresholdWindow*) thread->window;
 238                 window->lock_window("ThresholdMain::render_gui");
 239                 window->canvas->draw();
 240                 window->unlock_window();
 241         }
 242 }
 243
 244 void ThresholdMain::calculate_histogram(VFrame *frame)
 245 {
 246         if(!engine) engine = new HistogramEngine(get_project_smp() + 1,
 247                 get_project_smp() + 1);
 248         engine->process_packages(frame);
 249 }
 250
 251 int ThresholdMain::handle_opengl()
 252 {
 253 #ifdef HAVE_GL
 254         static const char *rgb_shader =
 255                 "uniform sampler2D tex;\n"
 256                 "uniform float min;\n"
 257                 "uniform float max;\n"
 258                 "uniform vec4 low_color;\n"
 259                 "uniform vec4 mid_color;\n"
 260                 "uniform vec4 high_color;\n"
 261                 "uniform vec3 rgb_to_y_vector;\n"
 262                 "uniform float yminf;\n"
 263                 "void main()\n"
 264                 "{\n"
 265                 "       vec4 pixel = texture2D(tex, gl_TexCoord[0].st);\n"
 266                 "       float v = dot(pixel.rgb, rgb_to_y_vector) + yminf;\n"
 267                 "       if(v < min)\n"
 268                 "               pixel = low_color;\n"
 269                 "       else if(v < max)\n"
 270                 "               pixel = mid_color;\n"
 271                 "       else\n"
 272                 "               pixel = high_color;\n"
 273                 "       gl_FragColor = pixel;\n"
 274                 "}\n";
 275
 276         static const char *yuv_shader =
 277                 "uniform sampler2D tex;\n"
 278                 "uniform float min;\n"
 279                 "uniform float max;\n"
 280                 "uniform vec4 low_color;\n"
 281                 "uniform vec4 mid_color;\n"
 282                 "uniform vec4 high_color;\n"
 283                 "void main()\n"
 284                 "{\n"
 285                 "       vec4 pixel = texture2D(tex, gl_TexCoord[0].st);\n"
 286                 "       if(pixel.r < min)\n"
 287                 "               pixel = low_color;\n"
 288                 "       else if(pixel.r < max)\n"
 289                 "               pixel = mid_color;\n"
 290                 "       else\n"
 291                 "               pixel = high_color;\n"
 292                 "       gl_FragColor = pixel;\n"
 293                 "}\n";
 294
 295         get_output()->to_texture();
 296         get_output()->enable_opengl();
 297
 298         int color_model = get_output()->get_color_model();
 299         bool is_yuv = BC_CModels::is_yuv(color_model);
 300         bool has_alpha = BC_CModels::has_alpha(color_model);
 301         unsigned int shader = VFrame::make_shader(0, is_yuv ? yuv_shader : rgb_shader, 0);
 302         if( shader > 0 ) {
 303                 glUseProgram(shader);
 304                 glUniform1i(glGetUniformLocation(shader, "tex"), 0);
 305                 glUniform1f(glGetUniformLocation(shader, "min"), config.min);
 306                 glUniform1f(glGetUniformLocation(shader, "max"), config.max);
 307
 308                 if (is_yuv) {
 309                         float y_low,  u_low,  v_low;
 310                         float y_mid,  u_mid,  v_mid;
 311                         float y_high, u_high, v_high;
 312
 313                         YUV::yuv.rgb_to_yuv_f(
 314                                         (float)config.low_color.r / 0xff,
 315                                         (float)config.low_color.g / 0xff,
 316                                         (float)config.low_color.b / 0xff,
 317                                         y_low, u_low, v_low);
 318                         u_low += 0.5;  v_low += 0.5;
 319                         YUV::yuv.rgb_to_yuv_f(
 320                                         (float)config.mid_color.r / 0xff,
 321                                         (float)config.mid_color.g / 0xff,
 322                                         (float)config.mid_color.b / 0xff,
 323                                         y_mid, u_mid, v_mid);
 324                         u_mid += 0.5;  v_mid += 0.5;
 325                         YUV::yuv.rgb_to_yuv_f(
 326                                         (float)config.high_color.r / 0xff,
 327                                         (float)config.high_color.g / 0xff,
 328                                         (float)config.high_color.b / 0xff,
 329                                         y_high, u_high, v_high);
 330                         u_high += 0.5;  v_high += 0.5;
 331
 332                         glUniform4f(glGetUniformLocation(shader, "low_color"),
 333                                         y_low, u_low, v_low,
 334                                         has_alpha ? (float)config.low_color.a / 0xff : 1.0);
 335                         glUniform4f(glGetUniformLocation(shader, "mid_color"),
 336                                         y_mid, u_mid, v_mid,
 337                                         has_alpha ? (float)config.mid_color.a / 0xff : 1.0);
 338                         glUniform4f(glGetUniformLocation(shader, "high_color"),
 339                                         y_high, u_high, v_high,
 340                                         has_alpha ? (float)config.high_color.a / 0xff : 1.0);
 341                 }
 342                 else {
 343                         glUniform4f(glGetUniformLocation(shader, "low_color"),
 344                                         (float)config.low_color.r / 0xff,
 345                                         (float)config.low_color.g / 0xff,
 346                                         (float)config.low_color.b / 0xff,
 347                                         has_alpha ? (float)config.low_color.a / 0xff : 1.0);
 348                         glUniform4f(glGetUniformLocation(shader, "mid_color"),
 349                                         (float)config.mid_color.r / 0xff,
 350                                         (float)config.mid_color.g / 0xff,
 351                                         (float)config.mid_color.b / 0xff,
 352                                         has_alpha ? (float)config.mid_color.a / 0xff : 1.0);
 353                         glUniform4f(glGetUniformLocation(shader, "high_color"),
 354                                         (float)config.high_color.r / 0xff,
 355                                         (float)config.high_color.g / 0xff,
 356                                         (float)config.high_color.b / 0xff,
 357                                         has_alpha ? (float)config.high_color.a / 0xff : 1.0);
 358                         BC_GL_RGB_TO_Y(shader);
 359                 }
 360         }
 361
 362         get_output()->init_screen();
 363         get_output()->bind_texture(0);
 364         get_output()->draw_texture();
 365         glUseProgram(0);
 366         get_output()->set_opengl_state(VFrame::SCREEN);
 367 #endif
 368         return 0;
 369 }
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392 ThresholdPackage::ThresholdPackage()
 393  : LoadPackage()
 394 {
 395         start = end = 0;
 396 }
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408 ThresholdUnit::ThresholdUnit(ThresholdEngine *server)
 409  : LoadClient(server)
 410 {
 411         this->server = server;
 412 }
 413
 414 // Coerces pixel component to int.
 415 static inline int get_component(unsigned char v)
 416 {
 417         return (v << 8) | v;
 418 }
 419
 420 static inline int get_component(float v)
 421 {
 422         return (int)(v * 0xffff);
 423 }
 424
 425 static inline int get_component(uint16_t v)
 426 {
 427         return v;
 428 }
 429
 430 // Rescales value in range [0, 255] to range appropriate to TYPE.
 431 template<typename TYPE>
 432 static TYPE scale_to_range(int v)
 433 {
 434         return v;  // works for unsigned char, override for the rest.
 435 }
 436
 437 template<>
 438 inline float scale_to_range(int v)
 439 {
 440         return (float) v / 0xff;
 441 }
 442
 443 template<>
 444 inline uint16_t scale_to_range(int v)
 445 {
 446         return v << 8 | v;
 447 }
 448
 449 static inline void rgb_to_yuv(unsigned char   r, unsigned char   g, unsigned char   b,
 450                               unsigned char & y, unsigned char & u, unsigned char & v)
 451 {
 452         YUV::yuv.rgb_to_yuv_8(r, g, b, y, u, v);
 453 }
 454
 455 static inline void rgb_to_yuv(float   r, float   g, float   b,
 456                               float & y, float & u, float & v)
 457 {
 458         YUV::yuv.rgb_to_yuv_f(r, g, b, y, u, v);
 459 }
 460
 461 static inline void rgb_to_yuv(uint16_t   r, uint16_t   g, uint16_t   b,
 462                               uint16_t & y, uint16_t & u, uint16_t & v)
 463 {
 464         YUV::yuv.rgb_to_yuv_16(r, g, b, y, u, v);
 465 }
 466
 467 template<typename TYPE, int COMPONENTS, bool USE_YUV>
 468 void ThresholdUnit::render_data(LoadPackage *package)
 469 {
 470         const ThresholdPackage *pkg = (ThresholdPackage*)package;
 471         const ThresholdConfig *config = & server->plugin->config;
 472         VFrame *data = server->data;
 473         const int min = (int)(config->min * 0xffff);
 474         const int max = (int)(config->max * 0xffff);
 475         const int w = data->get_w();
 476         //const int h = data->get_h();
 477
 478         const TYPE r_low = scale_to_range<TYPE>(config->low_color.r);
 479         const TYPE g_low = scale_to_range<TYPE>(config->low_color.g);
 480         const TYPE b_low = scale_to_range<TYPE>(config->low_color.b);
 481         const TYPE a_low = scale_to_range<TYPE>(config->low_color.a);
 482
 483         const TYPE r_mid = scale_to_range<TYPE>(config->mid_color.r);
 484         const TYPE g_mid = scale_to_range<TYPE>(config->mid_color.g);
 485         const TYPE b_mid = scale_to_range<TYPE>(config->mid_color.b);
 486         const TYPE a_mid = scale_to_range<TYPE>(config->mid_color.a);
 487
 488         const TYPE r_high = scale_to_range<TYPE>(config->high_color.r);
 489         const TYPE g_high = scale_to_range<TYPE>(config->high_color.g);
 490         const TYPE b_high = scale_to_range<TYPE>(config->high_color.b);
 491         const TYPE a_high = scale_to_range<TYPE>(config->high_color.a);
 492
 493         TYPE y_low,  u_low,  v_low;
 494         TYPE y_mid,  u_mid,  v_mid;
 495         TYPE y_high, u_high, v_high;
 496
 497         if (USE_YUV)
 498         {
 499                 rgb_to_yuv(r_low,  g_low,  b_low,  y_low,  u_low,  v_low);
 500                 rgb_to_yuv(r_mid,  g_mid,  b_mid,  y_mid,  u_mid,  v_mid);
 501                 rgb_to_yuv(r_high, g_high, b_high, y_high, u_high, v_high);
 502         }
 503
 504         for(int i = pkg->start; i < pkg->end; i++)
 505         {
 506                 TYPE *in_row = (TYPE*)data->get_rows()[i];
 507                 TYPE *out_row = in_row;
 508                 for(int j = 0; j < w; j++)
 509                 {
 510                         if (USE_YUV)
 511                         {
 512                                 const int y = get_component(in_row[0]);
 513                                 if (y < min)
 514                                 {
 515                                         *out_row++ = y_low;
 516                                         *out_row++ = u_low;
 517                                         *out_row++ = v_low;
 518                                         if(COMPONENTS == 4) *out_row++ = a_low;
 519                                 }
 520                                 else if (y < max)
 521                                 {
 522                                         *out_row++ = y_mid;
 523                                         *out_row++ = u_mid;
 524                                         *out_row++ = v_mid;
 525                                         if(COMPONENTS == 4) *out_row++ = a_mid;
 526                                 }
 527                                 else
 528                                 {
 529                                         *out_row++ = y_high;
 530                                         *out_row++ = u_high;
 531                                         *out_row++ = v_high;
 532                                         if(COMPONENTS == 4) *out_row++ = a_high;
 533                                 }
 534                         }
 535                         else
 536                         {
 537                                 const int r = get_component(in_row[0]);
 538                                 const int g = get_component(in_row[1]);
 539                                 const int b = get_component(in_row[2]);
 540                                 const int y = (r * 76 + g * 150 + b * 29) >> 8;
 541                                 if (y < min)
 542                                 {
 543                                         *out_row++ = r_low;
 544                                         *out_row++ = g_low;
 545                                         *out_row++ = b_low;
 546                                         if(COMPONENTS == 4) *out_row++ = a_low;
 547                                 }
 548                                 else if (y < max)
 549                                 {
 550                                         *out_row++ = r_mid;
 551                                         *out_row++ = g_mid;
 552                                         *out_row++ = b_mid;
 553                                         if(COMPONENTS == 4) *out_row++ = a_mid;
 554                                 }
 555                                 else
 556                                 {
 557                                         *out_row++ = r_high;
 558                                         *out_row++ = g_high;
 559                                         *out_row++ = b_high;
 560                                         if(COMPONENTS == 4) *out_row++ = a_high;
 561                                 }
 562                         }
 563                         in_row += COMPONENTS;
 564                 }
 565         }
 566 }
 567
 568 void ThresholdUnit::process_package(LoadPackage *package)
 569 {
 570         switch(server->data->get_color_model())
 571         {
 572                 case BC_RGB888:
 573                         render_data<unsigned char, 3, false>(package);
 574                         break;
 575
 576                 case BC_RGB_FLOAT:
 577                         render_data<float, 3, false>(package);
 578                         break;
 579
 580                 case BC_RGBA8888:
 581                         render_data<unsigned char, 4, false>(package);
 582                         break;
 583
 584                 case BC_RGBA_FLOAT:
 585                         render_data<float, 4, false>(package);
 586                         break;
 587
 588                 case BC_YUV888:
 589                         render_data<unsigned char, 3, true>(package);
 590                         break;
 591
 592                 case BC_YUVA8888:
 593                         render_data<unsigned char, 4, true>(package);
 594                         break;
 595
 596                 case BC_YUV161616:
 597                         render_data<uint16_t, 3, true>(package);
 598                         break;
 599
 600                 case BC_YUVA16161616:
 601                         render_data<uint16_t, 4, true>(package);
 602                         break;
 603         }
 604 }
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616 ThresholdEngine::ThresholdEngine(ThresholdMain *plugin)
 617  : LoadServer(plugin->get_project_smp() + 1,
 618         plugin->get_project_smp() + 1)
 619 {
 620         this->plugin = plugin;
 621 }
 622
 623 ThresholdEngine::~ThresholdEngine()
 624 {
 625 }
 626
 627 void ThresholdEngine::process_packages(VFrame *data)
 628 {
 629         this->data = data;
 630         LoadServer::process_packages();
 631 }
 632
 633 void ThresholdEngine::init_packages()
 634 {
 635         for(int i = 0; i < get_total_packages(); i++)
 636         {
 637                 ThresholdPackage *package = (ThresholdPackage*)get_package(i);
 638                 package->start = data->get_h() * i / get_total_packages();
 639                 package->end = data->get_h() * (i + 1) / get_total_packages();
 640         }
 641 }
 642
 643 LoadClient* ThresholdEngine::new_client()
 644 {
 645         return (LoadClient*)new ThresholdUnit(this);
 646 }
 647
 648 LoadPackage* ThresholdEngine::new_package()
 649 {
 650         return (LoadPackage*)new HistogramPackage;
 651 }
 652
 653
 654
 655
 656
 657
 658
 659
 660 RGBA::RGBA()
 661 {
 662         r = g = b = a = 0;
 663 }
 664
 665 RGBA::RGBA(int r, int g, int b, int a)
 666 {
 667         this->r = r;
 668         this->g = g;
 669         this->b = b;
 670         this->a = a;
 671 }
 672
 673 void RGBA::set(int r, int g, int b, int a)
 674 {
 675         this->r = r;
 676         this->g = g;
 677         this->b = b;
 678         this->a = a;
 679 }
 680
 681 void RGBA::set(int rgb, int alpha)
 682 {
 683         r = (rgb & 0xff0000) >> 16;
 684         g = (rgb & 0xff00)   >>  8;
 685         b = (rgb & 0xff);
 686         a = alpha;
 687 }
 688
 689 int RGBA::getRGB() const
 690 {
 691         return r << 16 | g << 8 | b;
 692 }
 693
 694 static void init_RGBA_keys(const char * prefix,
 695                            string & r_s,
 696                            string & g_s,
 697                            string & b_s,
 698                            string & a_s)
 699 {
 700         r_s = prefix;
 701         g_s = prefix;
 702         b_s = prefix;
 703         a_s = prefix;
 704
 705         r_s += "_R";
 706         g_s += "_G";
 707         b_s += "_B";
 708         a_s += "_A";
 709 }
 710
 711 void RGBA::set_property(XMLTag & tag, const char * prefix) const
 712 {
 713         string r_s, g_s, b_s, a_s;
 714         init_RGBA_keys(prefix, r_s, g_s, b_s, a_s);
 715
 716         tag.set_property(const_cast<char *>(r_s.c_str()), r);
 717         tag.set_property(const_cast<char *>(g_s.c_str()), g);
 718         tag.set_property(const_cast<char *>(b_s.c_str()), b);
 719         tag.set_property(const_cast<char *>(a_s.c_str()), a);
 720 }
 721
 722 RGBA RGBA::get_property(XMLTag & tag, const char * prefix) const
 723 {
 724         string r_s, g_s, b_s, a_s;
 725         init_RGBA_keys(prefix, r_s, g_s, b_s, a_s);
 726
 727         return RGBA(tag.get_property(const_cast<char *>(r_s.c_str()), r),
 728                     tag.get_property(const_cast<char *>(g_s.c_str()), g),
 729                     tag.get_property(const_cast<char *>(b_s.c_str()), b),
 730                     tag.get_property(const_cast<char *>(a_s.c_str()), a));
 731 }
 732
 733 bool operator==(const RGBA & a, const RGBA & b)
 734 {
 735         return  a.r == b.r &&
 736                 a.g == b.g &&
 737                 a.b == b.b &&
 738                 a.a == b.a;
 739 }
 740
 741 template<>
 742 RGBA interpolate(const RGBA & prev_color, const double & prev_scale, const RGBA &next_color, const double & next_scale)
 743 {
 744         return RGBA(interpolate(prev_color.r, prev_scale, next_color.r, next_scale),
 745                     interpolate(prev_color.g, prev_scale, next_color.g, next_scale),
 746                     interpolate(prev_color.b, prev_scale, next_color.b, next_scale),
 747                     interpolate(prev_color.a, prev_scale, next_color.a, next_scale));
 748 }