libs/canvas/wave_view.cc

   1 /*
   2     Copyright (C) 2011-2013 Paul Davis
   3     Author: Carl Hetherington <cth@carlh.net>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18
  19 */
  20
  21 #include <cmath>
  22 #include <cairomm/cairomm.h>
  23
  24 #include <glibmm/threads.h>
  25
  26 #include "gtkmm2ext/utils.h"
  27 #include "gtkmm2ext/gui_thread.h"
  28
  29 #include "pbd/base_ui.h"
  30 #include "pbd/compose.h"
  31 #include "pbd/convert.h"
  32 #include "pbd/signals.h"
  33 #include "pbd/stacktrace.h"
  34
  35 #include "ardour/types.h"
  36 #include "ardour/dB.h"
  37 #include "ardour/lmath.h"
  38 #include "ardour/audioregion.h"
  39 #include "ardour/audiosource.h"
  40
  41 #include "canvas/wave_view.h"
  42 #include "canvas/utils.h"
  43 #include "canvas/canvas.h"
  44 #include "canvas/colors.h"
  45
  46 #include <gdkmm/general.h>
  47
  48 #include "gtkmm2ext/gui_thread.h"
  49
  50 using namespace std;
  51 using namespace ARDOUR;
  52 using namespace ArdourCanvas;
  53
  54 double WaveView::_global_gradient_depth = 0.6;
  55 bool WaveView::_global_logscaled = false;
  56 WaveView::Shape WaveView::_global_shape = WaveView::Normal;
  57 bool WaveView::_global_show_waveform_clipping = true;
  58 double WaveView::_clip_level = 0.98853;
  59
  60 WaveViewCache* WaveView::images = 0;
  61 gint WaveView::drawing_thread_should_quit = 0;
  62 Glib::Threads::Mutex WaveView::request_queue_lock;
  63 Glib::Threads::Cond WaveView::request_cond;
  64 Glib::Threads::Thread* WaveView::_drawing_thread = 0;
  65 WaveView::DrawingRequestQueue WaveView::request_queue;
  66
  67 PBD::Signal0<void> WaveView::VisualPropertiesChanged;
  68 PBD::Signal0<void> WaveView::ClipLevelChanged;
  69
  70 WaveView::WaveView (Canvas* c, boost::shared_ptr<ARDOUR::AudioRegion> region)
  71         : Item (c)
  72         , _region (region)
  73         , _channel (0)
  74         , _samples_per_pixel (0)
  75         , _height (64)
  76         , _show_zero (false)
  77         , _zero_color (0xff0000ff)
  78         , _clip_color (0xff0000ff)
  79         , _logscaled (_global_logscaled)
  80         , _shape (_global_shape)
  81         , _gradient_depth (_global_gradient_depth)
  82         , _shape_independent (false)
  83         , _logscaled_independent (false)
  84         , _gradient_depth_independent (false)
  85         , _amplitude_above_axis (1.0)
  86         , _region_amplitude (region->scale_amplitude ())
  87         , _start_shift (0.0)
  88         , _region_start (region->start())
  89         , get_image_in_thread (false)
  90         , rendered (false)
  91 {
  92         VisualPropertiesChanged.connect_same_thread (invalidation_connection, boost::bind (&WaveView::handle_visual_property_change, this));
  93         ClipLevelChanged.connect_same_thread (invalidation_connection, boost::bind (&WaveView::handle_clip_level_change, this));
  94
  95         ImageReady.connect (image_ready_connection, MISSING_INVALIDATOR, boost::bind (&WaveView::image_ready, this), gui_context());
  96 }
  97
  98 WaveView::WaveView (Item* parent, boost::shared_ptr<ARDOUR::AudioRegion> region)
  99         : Item (parent)
 100         , _region (region)
 101         , _channel (0)
 102         , _samples_per_pixel (0)
 103         , _height (64)
 104         , _show_zero (false)
 105         , _zero_color (0xff0000ff)
 106         , _clip_color (0xff0000ff)
 107         , _logscaled (_global_logscaled)
 108         , _shape (_global_shape)
 109         , _gradient_depth (_global_gradient_depth)
 110         , _shape_independent (false)
 111         , _logscaled_independent (false)
 112         , _gradient_depth_independent (false)
 113         , _amplitude_above_axis (1.0)
 114         , _region_amplitude (region->scale_amplitude ())
 115         , _region_start (region->start())
 116         , get_image_in_thread (false)
 117         , rendered (false)
 118 {
 119         VisualPropertiesChanged.connect_same_thread (invalidation_connection, boost::bind (&WaveView::handle_visual_property_change, this));
 120         ClipLevelChanged.connect_same_thread (invalidation_connection, boost::bind (&WaveView::handle_clip_level_change, this));
 121
 122         ImageReady.connect (image_ready_connection, MISSING_INVALIDATOR, boost::bind (&WaveView::image_ready, this), gui_context());
 123 }
 124
 125 WaveView::~WaveView ()
 126 {
 127         invalidate_image_cache ();
 128 }
 129
 130 string
 131 WaveView::debug_name() const
 132 {
 133         return _region->name() + string (":") + PBD::to_string (_channel+1, std::dec);
 134 }
 135
 136 void
 137 WaveView::image_ready ()
 138 {
 139         redraw ();
 140 }
 141
 142 void
 143 WaveView::handle_visual_property_change ()
 144 {
 145         bool changed = false;
 146
 147         if (!_shape_independent && (_shape != global_shape())) {
 148                 _shape = global_shape();
 149                 changed = true;
 150         }
 151
 152         if (!_logscaled_independent && (_logscaled != global_logscaled())) {
 153                 _logscaled = global_logscaled();
 154                 changed = true;
 155         }
 156
 157         if (!_gradient_depth_independent && (_gradient_depth != global_gradient_depth())) {
 158                 _gradient_depth = global_gradient_depth();
 159                 changed = true;
 160         }
 161
 162         if (changed) {
 163                 begin_visual_change ();
 164                 invalidate_image_cache ();
 165                 end_visual_change ();
 166         }
 167 }
 168
 169 void
 170 WaveView::handle_clip_level_change ()
 171 {
 172         begin_visual_change ();
 173         invalidate_image_cache ();
 174         end_visual_change ();
 175 }
 176
 177 void
 178 WaveView::set_fill_color (Color c)
 179 {
 180         if (c != _fill_color) {
 181                 begin_visual_change ();
 182                 invalidate_image_cache ();
 183                 Fill::set_fill_color (c);
 184                 end_visual_change ();
 185         }
 186 }
 187
 188 void
 189 WaveView::set_outline_color (Color c)
 190 {
 191         if (c != _outline_color) {
 192                 begin_visual_change ();
 193                 invalidate_image_cache ();
 194                 Outline::set_outline_color (c);
 195                 end_visual_change ();
 196         }
 197 }
 198
 199 void
 200 WaveView::set_samples_per_pixel (double samples_per_pixel)
 201 {
 202         if (samples_per_pixel != _samples_per_pixel) {
 203                 begin_change ();
 204
 205                 invalidate_image_cache ();
 206                 _samples_per_pixel = samples_per_pixel;
 207                 _bounding_box_dirty = true;
 208
 209                 end_change ();
 210         }
 211 }
 212
 213 static inline float
 214 _log_meter (float power, double lower_db, double upper_db, double non_linearity)
 215 {
 216         return (power < lower_db ? 0.0 : pow((power-lower_db)/(upper_db-lower_db), non_linearity));
 217 }
 218
 219 static inline float
 220 alt_log_meter (float power)
 221 {
 222         return _log_meter (power, -192.0, 0.0, 8.0);
 223 }
 224
 225 void
 226 WaveView::set_clip_level (double dB)
 227 {
 228         const double clip_level = dB_to_coefficient (dB);
 229         if (clip_level != _clip_level) {
 230                 _clip_level = clip_level;
 231                 ClipLevelChanged ();
 232         }
 233 }
 234
 235 void
 236 WaveView::invalidate_image_cache ()
 237 {
 238         cancel_my_render_request ();
 239         _current_image.reset ();
 240 }
 241
 242 Coord
 243 WaveView::y_extent (double s, bool /*round_to_lower_edge*/) const
 244 {
 245         /* it is important that this returns an integral value, so that we
 246          * can ensure correct single pixel behaviour.
 247          *
 248          * we need (_height - max(wave_line_width))
 249          * wave_line_width == 1 IFF top==bottom (1 sample per pixel or flat line)
 250          * wave_line_width == 2 otherwise
 251          * then round away from the zero line, towards peak
 252          */
 253         if (_shape == Rectified) {
 254                 // we only ever have 1 point and align to the bottom (not center)
 255                 return floor ((1.0 - s) * (_height - 2.0));
 256         } else {
 257                 /* currently canvas rectangle is off-by-one and we
 258                  * cannot draw a pixel at 0 (-.5 .. +.5) without it being
 259                  * clipped. A value 1.0 (ideally one point at y=0) ends
 260                  * up a pixel down. and a value of -1.0 (ideally y = _height-1)
 261                  * currently is on the bottom separator line :(
 262                  * So to make the complete waveform appear centered in
 263                  * a region, we translate by +.5 (instead of -.5)
 264                  * and waste two pixel of height: -4 (instad of -2)
 265                  *
 266                  * This needs fixing in canvas/rectangle the intersect
 267                  * functions and probably a couple of other places as well...
 268                  */
 269                 Coord pos;
 270                 if (s < 0) {
 271                         pos = ceil  ((1.0 - s) * .5 * (_height - 4.0));
 272                 } else {
 273                         pos = floor ((1.0 - s) * .5 * (_height - 4.0));
 274                 }
 275                 return min (_height - 4.0, (max (0.0, pos)));
 276         }
 277 }
 278
 279 void
 280 WaveView::draw_absent_image (Cairo::RefPtr<Cairo::ImageSurface>& image, PeakData* _peaks, int n_peaks) const
 281 {
 282         Cairo::RefPtr<Cairo::ImageSurface> stripe = Cairo::ImageSurface::create (Cairo::FORMAT_A8, n_peaks, _height);
 283
 284         Cairo::RefPtr<Cairo::Context> stripe_context = Cairo::Context::create (stripe);
 285         stripe_context->set_antialias (Cairo::ANTIALIAS_NONE);
 286
 287         uint32_t stripe_separation = 150;
 288         double start = - floor (_height / stripe_separation) * stripe_separation;
 289         int stripe_x = 0;
 290
 291         while (start < n_peaks) {
 292
 293                 stripe_context->move_to (start, 0);
 294                 stripe_x = start + _height;
 295                 stripe_context->line_to (stripe_x, _height);
 296                 start += stripe_separation;
 297         }
 298
 299         stripe_context->set_source_rgba (1.0, 1.0, 1.0, 1.0);
 300         stripe_context->set_line_cap (Cairo::LINE_CAP_SQUARE);
 301         stripe_context->set_line_width(50);
 302         stripe_context->stroke();
 303
 304         Cairo::RefPtr<Cairo::Context> context = Cairo::Context::create (image);
 305
 306         context->set_source_rgba (1.0, 1.0, 0.0, 0.3);
 307         context->mask (stripe, 0, 0);
 308         context->fill ();
 309 }
 310
 311 struct LineTips {
 312         double top;
 313         double bot;
 314         double spread;
 315         bool clip_max;
 316         bool clip_min;
 317
 318         LineTips() : top (0.0), bot (0.0), clip_max (false), clip_min (false) {}
 319 };
 320
 321 struct ImageSet {
 322         Cairo::RefPtr<Cairo::ImageSurface> wave;
 323         Cairo::RefPtr<Cairo::ImageSurface> outline;
 324         Cairo::RefPtr<Cairo::ImageSurface> clip;
 325         Cairo::RefPtr<Cairo::ImageSurface> zero;
 326
 327         ImageSet() :
 328                 wave (0), outline (0), clip (0), zero (0) {}
 329 };
 330
 331 void
 332 WaveView::draw_image (Cairo::RefPtr<Cairo::ImageSurface>& image, PeakData* _peaks, int n_peaks, boost::shared_ptr<WaveViewThreadRequest> req) const
 333 {
 334
 335         ImageSet images;
 336
 337         images.wave = Cairo::ImageSurface::create (Cairo::FORMAT_A8, n_peaks, _height);
 338         images.outline = Cairo::ImageSurface::create (Cairo::FORMAT_A8, n_peaks, _height);
 339         images.clip = Cairo::ImageSurface::create (Cairo::FORMAT_A8, n_peaks, _height);
 340         images.zero = Cairo::ImageSurface::create (Cairo::FORMAT_A8, n_peaks, _height);
 341
 342         Cairo::RefPtr<Cairo::Context> wave_context = Cairo::Context::create (images.wave);
 343         Cairo::RefPtr<Cairo::Context> outline_context = Cairo::Context::create (images.outline);
 344         Cairo::RefPtr<Cairo::Context> clip_context = Cairo::Context::create (images.clip);
 345         Cairo::RefPtr<Cairo::Context> zero_context = Cairo::Context::create (images.zero);
 346         wave_context->set_antialias (Cairo::ANTIALIAS_NONE);
 347         outline_context->set_antialias (Cairo::ANTIALIAS_NONE);
 348         clip_context->set_antialias (Cairo::ANTIALIAS_NONE);
 349         zero_context->set_antialias (Cairo::ANTIALIAS_NONE);
 350
 351         boost::scoped_array<LineTips> tips (new LineTips[n_peaks]);
 352
 353         /* Clip level nominally set to -0.9dBFS to account for inter-sample
 354            interpolation possibly clipping (value may be too low).
 355
 356            We adjust by the region's own gain (but note: not by any gain
 357            automation or its gain envelope) so that clip indicators are closer
 358            to providing data about on-disk data. This multiplication is
 359            needed because the data we get from AudioRegion::read_peaks()
 360            has been scaled by scale_amplitude() already.
 361         */
 362
 363         const double clip_level = _clip_level * _region_amplitude;
 364
 365         if (_shape == WaveView::Rectified) {
 366
 367                 /* each peak is a line from the bottom of the waveview
 368                  * to a point determined by max (_peaks[i].max,
 369                  * _peaks[i].min)
 370                  */
 371
 372                 if (_logscaled) {
 373                         for (int i = 0; i < n_peaks; ++i) {
 374
 375                                 tips[i].bot = height() - 1.0;
 376                                 const double p = alt_log_meter (fast_coefficient_to_dB (max (fabs (_peaks[i].max), fabs (_peaks[i].min))));
 377                                 tips[i].top = y_extent (p, false);
 378                                 tips[i].spread = p * (_height - 1.0);
 379
 380                                 if (_peaks[i].max >= clip_level) {
 381                                         tips[i].clip_max = true;
 382                                 }
 383
 384                                 if (-(_peaks[i].min) >= clip_level) {
 385                                         tips[i].clip_min = true;
 386                                 }
 387                         }
 388
 389                 } else {
 390                         for (int i = 0; i < n_peaks; ++i) {
 391
 392                                 tips[i].bot = height() - 1.0;
 393                                 const double p = max(fabs (_peaks[i].max), fabs (_peaks[i].min));
 394                                 tips[i].top = y_extent (p, false);
 395                                 tips[i].spread = p * (_height - 2.0);
 396                                 if (p >= clip_level) {
 397                                         tips[i].clip_max = true;
 398                                 }
 399                         }
 400
 401                 }
 402
 403         } else {
 404
 405                 if (_logscaled) {
 406                         for (int i = 0; i < n_peaks; ++i) {
 407                                 double top = _peaks[i].max;
 408                                 double bot = _peaks[i].min;
 409
 410                                 if (_peaks[i].max >= clip_level) {
 411                                                 tips[i].clip_max = true;
 412                                 }
 413                                 if (-(_peaks[i].min) >= clip_level) {
 414                                         tips[i].clip_min = true;
 415                                 }
 416
 417                                 if (top > 0.0) {
 418                                         top = alt_log_meter (fast_coefficient_to_dB (top));
 419                                 } else if (top < 0.0) {
 420                                         top =-alt_log_meter (fast_coefficient_to_dB (-top));
 421                                 } else {
 422                                         top = 0.0;
 423                                 }
 424
 425                                 if (bot > 0.0) {
 426                                         bot = alt_log_meter (fast_coefficient_to_dB (bot));
 427                                 } else if (bot < 0.0) {
 428                                         bot = -alt_log_meter (fast_coefficient_to_dB (-bot));
 429                                 } else {
 430                                         bot = 0.0;
 431                                 }
 432
 433                                 tips[i].top = y_extent (top, false);
 434                                 tips[i].bot = y_extent (bot, true);
 435                                 tips[i].spread = tips[i].bot - tips[i].top;
 436                         }
 437
 438                 } else {
 439                         for (int i = 0; i < n_peaks; ++i) {
 440                                 if (_peaks[i].max >= clip_level) {
 441                                         tips[i].clip_max = true;
 442                                 }
 443                                 if (-(_peaks[i].min) >= clip_level) {
 444                                         tips[i].clip_min = true;
 445                                 }
 446
 447                                 tips[i].top = y_extent (_peaks[i].max, false);
 448                                 tips[i].bot = y_extent (_peaks[i].min, true);
 449                                 tips[i].spread = tips[i].bot - tips[i].top;
 450                         }
 451
 452                 }
 453         }
 454
 455         if (req->should_stop()) {
 456                 return;
 457         }
 458
 459         Color alpha_one = rgba_to_color (0, 0, 0, 1.0);
 460
 461         set_source_rgba (wave_context, alpha_one);
 462         set_source_rgba (outline_context, alpha_one);
 463         set_source_rgba (clip_context, alpha_one);
 464         set_source_rgba (zero_context, alpha_one);
 465
 466         /* ensure single-pixel lines */
 467
 468         wave_context->set_line_width (1.0);
 469         wave_context->translate (0.5, +1.5);
 470
 471         outline_context->set_line_width (1.0);
 472         outline_context->translate (0.5, +1.5);
 473
 474         clip_context->set_line_width (1.0);
 475         clip_context->translate (0.5, +1.5);
 476
 477         zero_context->set_line_width (1.0);
 478         zero_context->translate (0.5, +1.5);
 479
 480         /* the height of the clip-indicator should be at most 7 pixels,
 481          * or 5% of the height of the waveview item.
 482          */
 483
 484         const double clip_height = min (7.0, ceil (_height * 0.05));
 485
 486         /* There are 3 possible components to draw at each x-axis position: the
 487            waveform "line", the zero line and an outline/clip indicator.  We
 488            have to decide which of the 3 to draw at each position, pixel by
 489            pixel. This makes the rendering less efficient but it is the only
 490            way I can see to do this correctly.
 491
 492            To avoid constant source swapping and stroking, we draw the components separately
 493            onto four alpha only image surfaces for use as a mask.
 494
 495            With only 1 pixel of spread between the top and bottom of the line,
 496            we just draw the upper outline/clip indicator.
 497
 498            With 2 pixels of spread, we draw the upper and lower outline clip
 499            indicators.
 500
 501            With 3 pixels of spread we draw the upper and lower outline/clip
 502            indicators and at least 1 pixel of the waveform line.
 503
 504            With 5 pixels of spread, we draw all components.
 505
 506            We can do rectified as two separate passes because we have a much
 507            easier decision regarding whether to draw the waveform line. We
 508            always draw the clip/outline indicators.
 509         */
 510
 511         if (_shape == WaveView::Rectified) {
 512
 513                 for (int i = 0; i < n_peaks; ++i) {
 514
 515                         /* waveform line */
 516
 517                         if (tips[i].spread >= 1.0) {
 518                                 wave_context->move_to (i, tips[i].top);
 519                                 wave_context->line_to (i, tips[i].bot);
 520                         }
 521
 522                         /* clip indicator */
 523
 524                         if (_global_show_waveform_clipping && (tips[i].clip_max || tips[i].clip_min)) {
 525                                 clip_context->move_to (i, tips[i].top);
 526                                 /* clip-indicating upper terminal line */
 527                                 clip_context->rel_line_to (0, min (clip_height, ceil(tips[i].spread + .5)));
 528                         } else {
 529                                 outline_context->move_to (i, tips[i].top);
 530                                 /* normal upper terminal dot */
 531                                 outline_context->rel_line_to (0, -1.0);
 532                         }
 533                 }
 534
 535                 wave_context->stroke ();
 536                 clip_context->stroke ();
 537                 outline_context->stroke ();
 538
 539         } else {
 540                 const double height_2 = (_height - 2.5) * .5;
 541
 542                 for (int i = 0; i < n_peaks; ++i) {
 543
 544                         /* waveform line */
 545
 546                         if (tips[i].spread >= 2.0) {
 547                                 wave_context->move_to (i, tips[i].top);
 548                                 wave_context->line_to (i, tips[i].bot);
 549                         }
 550                         /* draw square waves and other discontiguous points clearly */
 551                         if (i > 0) {
 552                                 if (tips[i-1].top + 2 < tips[i].top) {
 553                                         wave_context->move_to (i-1, tips[i-1].top);
 554                                         wave_context->line_to (i-1, (tips[i].bot + tips[i-1].top)/2);
 555                                         wave_context->move_to (i, (tips[i].bot + tips[i-1].top)/2);
 556                                         wave_context->line_to (i, tips[i].top);
 557                                 } else if (tips[i-1].bot > tips[i].bot + 2) {
 558                                         wave_context->move_to (i-1, tips[i-1].bot);
 559                                         wave_context->line_to (i-1, (tips[i].top + tips[i-1].bot)/2);
 560                                         wave_context->move_to (i, (tips[i].top + tips[i-1].bot)/2);
 561                                         wave_context->line_to (i, tips[i].bot);
 562                                 }
 563                         }
 564
 565                         /* zero line */
 566
 567                         if (tips[i].spread >= 5.0 && show_zero_line()) {
 568                                 zero_context->move_to (i, floor(height_2));
 569                                 zero_context->rel_line_to (1.0, 0);
 570                         }
 571
 572                         if (tips[i].spread > 1.0) {
 573                                 bool clipped = false;
 574                                 /* outline/clip indicators */
 575                                 if (_global_show_waveform_clipping && tips[i].clip_max) {
 576                                         clip_context->move_to (i, tips[i].top);
 577                                         /* clip-indicating upper terminal line */
 578                                         clip_context->rel_line_to (0, min (clip_height, ceil(tips[i].spread + 0.5)));
 579                                         clipped = true;
 580                                 }
 581
 582                                 if (_global_show_waveform_clipping && tips[i].clip_min) {
 583                                         clip_context->move_to (i, tips[i].bot);
 584                                         /* clip-indicating lower terminal line */
 585                                         clip_context->rel_line_to (0, - min (clip_height, ceil(tips[i].spread + 0.5)));
 586                                         clipped = true;
 587                                 }
 588
 589                                 if (!clipped) {
 590                                         outline_context->move_to (i, tips[i].bot + 1.0);
 591                                         /* normal lower terminal dot */
 592                                         outline_context->rel_line_to (0, -1.0);
 593
 594                                         outline_context->move_to (i, tips[i].top - 1.0);
 595                                         /* normal upper terminal dot */
 596                                         outline_context->rel_line_to (0, 1.0);
 597                                 }
 598                         } else {
 599                                 bool clipped = false;
 600                                 /* outline/clip indicator */
 601                                 if (_global_show_waveform_clipping && (tips[i].clip_max || tips[i].clip_min)) {
 602                                         clip_context->move_to (i, tips[i].top);
 603                                         /* clip-indicating upper / lower terminal line */
 604                                         clip_context->rel_line_to (0, 1.0);
 605                                         clipped = true;
 606                                 }
 607
 608                                 if (!clipped) {
 609                                         wave_context->move_to (i, tips[i].top);
 610                                         /* special case where outline only is drawn.
 611                                          * we draw a 1px "line", pretending that the span is 1.0
 612                                         */
 613                                         wave_context->rel_line_to (0, 1.0);
 614                                 }
 615                         }
 616                 }
 617
 618                 wave_context->stroke ();
 619                 outline_context->stroke ();
 620                 clip_context->stroke ();
 621                 zero_context->stroke ();
 622         }
 623
 624         if (req->should_stop()) {
 625                 return;
 626         }
 627
 628         Cairo::RefPtr<Cairo::Context> context = Cairo::Context::create (image);
 629
 630         /* Here we set a source colour and use the various components as a mask. */
 631
 632         if (gradient_depth() != 0.0) {
 633
 634                 Cairo::RefPtr<Cairo::LinearGradient> gradient (Cairo::LinearGradient::create (0, 0, 0, _height));
 635
 636                 double stops[3];
 637
 638                 double r, g, b, a;
 639
 640                 if (_shape == Rectified) {
 641                         stops[0] = 0.1;
 642                         stops[1] = 0.3;
 643                         stops[2] = 0.9;
 644                 } else {
 645                         stops[0] = 0.1;
 646                         stops[1] = 0.5;
 647                         stops[2] = 0.9;
 648                 }
 649
 650                 color_to_rgba (_fill_color, r, g, b, a);
 651                 gradient->add_color_stop_rgba (stops[1], r, g, b, a);
 652                 /* generate a new color for the middle of the gradient */
 653                 double h, s, v;
 654                 color_to_hsv (_fill_color, h, s, v);
 655                 /* change v towards white */
 656                 v *= 1.0 - gradient_depth();
 657                 Color center = hsva_to_color (h, s, v, a);
 658                 color_to_rgba (center, r, g, b, a);
 659
 660                 gradient->add_color_stop_rgba (stops[0], r, g, b, a);
 661                 gradient->add_color_stop_rgba (stops[2], r, g, b, a);
 662
 663                 context->set_source (gradient);
 664         } else {
 665                 set_source_rgba (context, _fill_color);
 666         }
 667
 668         if (req->should_stop()) {
 669                 return;
 670         }
 671
 672         context->mask (images.wave, 0, 0);
 673         context->fill ();
 674
 675         set_source_rgba (context, _outline_color);
 676         context->mask (images.outline, 0, 0);
 677         context->fill ();
 678
 679         set_source_rgba (context, _clip_color);
 680         context->mask (images.clip, 0, 0);
 681         context->fill ();
 682
 683         set_source_rgba (context, _zero_color);
 684         context->mask (images.zero, 0, 0);
 685         context->fill ();
 686 }
 687
 688 boost::shared_ptr<WaveViewCache::Entry>
 689 WaveView::cache_request_result (boost::shared_ptr<WaveViewThreadRequest> req) const
 690 {
 691         boost::shared_ptr<WaveViewCache::Entry> ret (new WaveViewCache::Entry (req->channel,
 692                                                                                req->height,
 693                                                                                req->region_amplitude,
 694                                                                                req->fill_color,
 695                                                                                req->samples_per_pixel,
 696                                                                                req->start,
 697                                                                                req->end,
 698                                                                                req->image));
 699         if (!images) {
 700                 images = new WaveViewCache;
 701         }
 702
 703         images->add (_region->audio_source (_channel), ret);
 704
 705         /* consolidate cache first (removes fully-contained
 706          * duplicate images)
 707          */
 708
 709         images->consolidate_image_cache (_region->audio_source (_channel),
 710                                          _channel, _height, _region_amplitude,
 711                                          _fill_color, _samples_per_pixel);
 712
 713         return ret;
 714 }
 715
 716 boost::shared_ptr<WaveViewCache::Entry>
 717 WaveView::get_image (framepos_t start, framepos_t end) const
 718 {
 719         boost::shared_ptr<WaveViewCache::Entry> ret;
 720
 721         /* this is called from a ::render() call, when we need an image to
 722            draw with.
 723         */
 724
 725         {
 726                 Glib::Threads::Mutex::Lock lmq (request_queue_lock);
 727
 728                 /* if there's a draw request outstanding, check to see if we
 729                  * have an image there. if so, use it (and put it in the cache
 730                  * while we're here.
 731                  */
 732
 733                 if (current_request && !current_request->should_stop() && current_request->image) {
 734
 735                         /* put the image into the cache so that other
 736                          * WaveViews can use it if it is useful
 737                          */
 738
 739                         if (current_request->start <= start && current_request->end >= end) {
 740
 741                                 ret.reset (new WaveViewCache::Entry (current_request->channel,
 742                                                                      current_request->height,
 743                                                                      current_request->region_amplitude,
 744                                                                      current_request->fill_color,
 745                                                                      current_request->samples_per_pixel,
 746                                                                      current_request->start,
 747                                                                      current_request->end,
 748                                                                      current_request->image));
 749
 750                                 cache_request_result (current_request);
 751                         }
 752
 753                         /* drop our handle on the current request */
 754                         current_request.reset ();
 755                 }
 756         }
 757
 758         if (!ret) {
 759
 760                 /* no current image draw request, so look in the cache */
 761
 762                 ret = get_image_from_cache (start, end);
 763
 764         }
 765
 766         if (!ret) {
 767
 768                 if (get_image_in_thread) {
 769
 770                         boost::shared_ptr<WaveViewThreadRequest> req (new WaveViewThreadRequest);
 771
 772                         req->type = WaveViewThreadRequest::Draw;
 773                         req->start = start;
 774                         req->end = end;
 775                         req->samples_per_pixel = _samples_per_pixel;
 776                         req->region = _region; /* weak ptr, to avoid storing a reference in the request queue */
 777                         req->channel = _channel;
 778                         req->width = _canvas->visible_area().width();
 779                         req->height = _height;
 780                         req->fill_color = _fill_color;
 781                         req->region_amplitude = _region_amplitude;
 782
 783                         /* draw image in this (the GUI thread) */
 784
 785                         generate_image (req, false);
 786
 787                         /* cache the result */
 788
 789                         ret = cache_request_result (req);
 790
 791                         /* reset this so that future missing images are
 792                          * generated in a a worker thread.
 793                          */
 794
 795                         get_image_in_thread = false;
 796
 797                 } else {
 798                         queue_get_image (_region, start, end);
 799                 }
 800         }
 801
 802
 803         return ret;
 804 }
 805
 806 boost::shared_ptr<WaveViewCache::Entry>
 807 WaveView::get_image_from_cache (framepos_t start, framepos_t end) const
 808 {
 809         if (!images) {
 810                 return boost::shared_ptr<WaveViewCache::Entry>();
 811         }
 812
 813         return images->lookup_image (_region->audio_source (_channel), start, end, _channel,
 814                                      _height, _region_amplitude, _fill_color, _samples_per_pixel);
 815 }
 816
 817 void
 818 WaveView::queue_get_image (boost::shared_ptr<const ARDOUR::Region> region, framepos_t start, framepos_t end) const
 819 {
 820         boost::shared_ptr<WaveViewThreadRequest> req (new WaveViewThreadRequest);
 821
 822         req->type = WaveViewThreadRequest::Draw;
 823         req->start = start;
 824         req->end = end;
 825         req->samples_per_pixel = _samples_per_pixel;
 826         req->region = _region; /* weak ptr, to avoid storing a reference in the request queue */
 827         req->channel = _channel;
 828         req->width = _canvas->visible_area().width();
 829         req->height = _height;
 830         req->fill_color = _fill_color;
 831         req->region_amplitude = _region_amplitude;
 832
 833         send_request (req);
 834 }
 835
 836 void
 837 WaveView::generate_image (boost::shared_ptr<WaveViewThreadRequest> req, bool in_render_thread) const
 838 {
 839         if (!req->should_stop()) {
 840
 841                 /* sample position is canonical here, and we want to generate
 842                  * an image that spans about twice the canvas width
 843                  */
 844
 845                 const framepos_t center = req->start + ((req->end - req->start) / 2);
 846                 const framecnt_t image_samples = req->width * req->samples_per_pixel; /* one canvas width */
 847
 848                 /* we can request data from anywhere in the Source, between 0 and its length
 849                  */
 850
 851                 framepos_t sample_start = max (_region_start, (center - image_samples));
 852                 framepos_t sample_end = min (center + image_samples, region_end());
 853
 854                 const int n_peaks = llrintf ((sample_end - sample_start)/ (req->samples_per_pixel));
 855
 856                 boost::scoped_array<ARDOUR::PeakData> peaks (new PeakData[n_peaks]);
 857
 858                 /* Note that Region::read_peaks() takes a start position based on an
 859                    offset into the Region's **SOURCE**, rather than an offset into
 860                    the Region itself.
 861                 */
 862
 863                 _region->read_peaks (peaks.get(), n_peaks,
 864                                      sample_start, sample_end - sample_start,
 865                                      req->channel,
 866                                      req->samples_per_pixel);
 867
 868
 869                 // apply waveform amplitude zoom multiplier
 870
 871                 for (int i = 0; i < n_peaks; ++i) {
 872                         peaks[i].max *= _amplitude_above_axis;
 873                         peaks[i].min *= _amplitude_above_axis;
 874                 }
 875
 876                 req->image = Cairo::ImageSurface::create (Cairo::FORMAT_ARGB32, n_peaks, req->height);
 877
 878                 /* make sure we record the sample positions that were actually used */
 879
 880                 req->start = sample_start;
 881                 req->end = sample_end;
 882
 883                 draw_image (req->image, peaks.get(), n_peaks, req);
 884         }
 885
 886         if (in_render_thread && !req->should_stop()) {
 887                 const_cast<WaveView*>(this)->ImageReady (); /* emit signal */
 888         }
 889
 890         return;
 891 }
 892
 893 /** Given a waveform that starts at window x-coordinate @param wave_origin
 894  * and the first pixel that we will actually draw @param draw_start, return
 895  * the offset into an image of the entire waveform that we will need to use.
 896  *
 897  * Note: most of our cached images are NOT of the entire waveform, this is just
 898  * computationally useful when determining which the sample range span for
 899  * the image we need.
 900  */
 901 static inline double
 902 window_to_image (double wave_origin, double image_start)
 903 {
 904         return image_start - wave_origin;
 905 }
 906
 907 void
 908 WaveView::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 909 {
 910         assert (_samples_per_pixel != 0);
 911
 912         if (!rendered) {
 913                 /* first image generation should happen in RENDER thread */
 914                 get_image_in_thread = false;
 915                 rendered = true; /* comments in header file */
 916         }
 917
 918         if (!_region) {
 919                 return;
 920         }
 921
 922         /* a WaveView is intimately connected to an AudioRegion. It will
 923          * display the waveform within the region, anywhere from the start of
 924          * the region to its end.
 925          *
 926          * the area we've been aked to render may overlap with area covered
 927          * by the region in any of the normal ways:
 928          *
 929          *  - it may begin and end within the area covered by the region
 930          *  - it may start before and end after the area covered by region
 931          *  - it may start before and end within the area covered by the region
 932          *  - it may start within and end after the area covered by the region
 933          *  - it may be precisely coincident with the area covered by region.
 934          *
 935          * So let's start by determining the area covered by the region, in
 936          * window coordinates. It begins at zero (in item coordinates for this
 937          * waveview, and extends to region_length() / _samples_per_pixel.
 938          */
 939
 940         Rect self = item_to_window (Rect (0.0, 0.0, region_length() / _samples_per_pixel, _height));
 941
 942         /* Now lets get the intersection with the area we've been asked to draw */
 943
 944         boost::optional<Rect> d = self.intersection (area);
 945
 946         if (!d) {
 947                 return;
 948         }
 949
 950         Rect draw = d.get();
 951
 952         /* "draw" is now a rectangle that defines the rectangle we need to
 953          * update/render the waveview into, in window coordinate space.
 954          */
 955
 956         /* window coordinates - pixels where x=0 is the left edge of the canvas
 957          * window. We round down in case we were asked to
 958          * draw "between" pixels at the start and/or end.
 959          */
 960
 961         double draw_start = floor (draw.x0);
 962         const double draw_end = floor (draw.x1);
 963
 964         // cerr << "Need to draw " << draw_start << " .. " << draw_end << " vs. " << area << " and self = " << self << endl;
 965
 966         /* image coordnates: pixels where x=0 is the start of this waveview,
 967          * wherever it may be positioned. thus image_start=N means "an image
 968          * that begins N pixels after the start of region that this waveview is
 969          * representing.
 970          */
 971
 972         const framepos_t image_start = window_to_image (self.x0, draw_start);
 973         const framepos_t image_end = window_to_image (self.x0, draw_end);
 974
 975         // cerr << "Image/WV space: " << image_start << " .. " << image_end << endl;
 976
 977         /* sample coordinates - note, these are not subject to rounding error
 978          *
 979          * "sample_start = N" means "the first sample we need to represent is N
 980          * samples after the first sample of the region"
 981          */
 982
 983         framepos_t sample_start = _region_start + (image_start * _samples_per_pixel);
 984         framepos_t sample_end   = _region_start + (image_end * _samples_per_pixel);
 985
 986         // cerr << "Sample space: " << sample_start << " .. " << sample_end << " @ " << _samples_per_pixel << " rs = " << _region_start << endl;
 987
 988         /* sample_start and sample_end are bounded by the region
 989          * limits. sample_start, because of the was just computed, must already
 990          * be greater than or equal to the _region_start value.
 991          */
 992
 993         sample_end = min (region_end(), sample_end);
 994
 995         // cerr << debug_name() << " will need image spanning " << sample_start << " .. " << sample_end << " region spans " << _region_start << " .. " << region_end() << endl;
 996
 997         double image_offset;
 998
 999         if (_current_image) {
1000
1001                 /* check it covers the right sample range */
1002
1003                 if (_current_image->start > sample_start || _current_image->end < sample_end) {
1004                         /* doesn't cover the area we need ... reset */
1005                         _current_image.reset ();
1006                 } else {
1007                         /* timestamp our continuing use of this image/cache entry */
1008                         images->use (_region->audio_source (_channel), _current_image);
1009                 }
1010         }
1011
1012         if (!_current_image) {
1013
1014                 /* look it up */
1015
1016                 _current_image = get_image (sample_start, sample_end);
1017
1018                 if (!_current_image) {
1019                         /* image not currently available. A redraw will be scheduled
1020                            when it is ready.
1021                         */
1022                         return;
1023                 }
1024         }
1025
1026         /* fix up offset: returned value is the first sample of the returned image */
1027
1028         image_offset = (_current_image->start - _region_start) / _samples_per_pixel;
1029
1030         // cerr << "Offset into image to place at zero: " << image_offset << endl;
1031
1032         if (_start_shift && (sample_start == _region_start) && (self.x0 == draw.x0)) {
1033                 /* we are going to draw the first pixel for this region, but
1034                    we may not want this to overlap a border around the
1035                    waveform. If so, _start_shift will be set.
1036                 */
1037                 //cerr << name.substr (23) << " ss = " << sample_start << " rs = " << _region_start << " sf = " << _start_shift << " ds = " << draw_start << " self = " << self << " draw = " << draw << endl;
1038                 //draw_start += _start_shift;
1039                 //image_offset += _start_shift;
1040         }
1041
1042         context->rectangle (draw_start, draw.y0, draw_end - draw_start, draw.height());
1043
1044         /* round image origin position to an exact pixel in device space to
1045          * avoid blurring
1046          */
1047
1048         double x  = self.x0 + image_offset;
1049         double y  = self.y0;
1050         context->user_to_device (x, y);
1051         x = round (x);
1052         y = round (y);
1053         context->device_to_user (x, y);
1054
1055         context->set_source (_current_image->image, x, y);
1056         context->fill ();
1057
1058 }
1059
1060 void
1061 WaveView::compute_bounding_box () const
1062 {
1063         if (_region) {
1064                 _bounding_box = Rect (0.0, 0.0, region_length() / _samples_per_pixel, _height);
1065         } else {
1066                 _bounding_box = boost::optional<Rect> ();
1067         }
1068
1069         _bounding_box_dirty = false;
1070 }
1071
1072 void
1073 WaveView::set_height (Distance height)
1074 {
1075         if (height != _height) {
1076                 begin_change ();
1077
1078                 invalidate_image_cache ();
1079                 _height = height;
1080                 get_image_in_thread = true;
1081
1082                 _bounding_box_dirty = true;
1083                 end_change ();
1084         }
1085 }
1086
1087 void
1088 WaveView::set_channel (int channel)
1089 {
1090         if (channel != _channel) {
1091                 begin_change ();
1092
1093                 invalidate_image_cache ();
1094                 _channel = channel;
1095
1096                 _bounding_box_dirty = true;
1097                 end_change ();
1098         }
1099 }
1100
1101 void
1102 WaveView::set_logscaled (bool yn)
1103 {
1104         if (_logscaled != yn) {
1105                 begin_visual_change ();
1106                 invalidate_image_cache ();
1107                 _logscaled = yn;
1108                 end_visual_change ();
1109         }
1110 }
1111
1112 void
1113 WaveView::gain_changed ()
1114 {
1115         begin_visual_change ();
1116         invalidate_image_cache ();
1117         _region_amplitude = _region->scale_amplitude ();
1118         end_visual_change ();
1119 }
1120
1121 void
1122 WaveView::set_zero_color (Color c)
1123 {
1124         if (_zero_color != c) {
1125                 begin_visual_change ();
1126                 invalidate_image_cache ();
1127                 _zero_color = c;
1128                 end_visual_change ();
1129         }
1130 }
1131
1132 void
1133 WaveView::set_clip_color (Color c)
1134 {
1135         if (_clip_color != c) {
1136                 begin_visual_change ();
1137                 invalidate_image_cache ();
1138                 _clip_color = c;
1139                 end_visual_change ();
1140         }
1141 }
1142
1143 void
1144 WaveView::set_show_zero_line (bool yn)
1145 {
1146         if (_show_zero != yn) {
1147                 begin_visual_change ();
1148                 invalidate_image_cache ();
1149                 _show_zero = yn;
1150                 end_visual_change ();
1151         }
1152 }
1153
1154 void
1155 WaveView::set_shape (Shape s)
1156 {
1157         if (_shape != s) {
1158                 begin_visual_change ();
1159                 invalidate_image_cache ();
1160                 _shape = s;
1161                 end_visual_change ();
1162         }
1163 }
1164
1165 void
1166 WaveView::set_amplitude_above_axis (double a)
1167 {
1168         if (fabs (_amplitude_above_axis - a) > 0.01) {
1169                 begin_visual_change ();
1170                 invalidate_image_cache ();
1171                 _amplitude_above_axis = a;
1172                 end_visual_change ();
1173         }
1174 }
1175
1176 void
1177 WaveView::set_global_shape (Shape s)
1178 {
1179         if (_global_shape != s) {
1180                 _global_shape = s;
1181                 VisualPropertiesChanged (); /* EMIT SIGNAL */
1182         }
1183 }
1184
1185 void
1186 WaveView::set_global_logscaled (bool yn)
1187 {
1188         if (_global_logscaled != yn) {
1189                 _global_logscaled = yn;
1190                 VisualPropertiesChanged (); /* EMIT SIGNAL */
1191         }
1192 }
1193
1194 framecnt_t
1195 WaveView::region_length() const
1196 {
1197         return _region->length() - (_region_start - _region->start());
1198 }
1199
1200 framepos_t
1201 WaveView::region_end() const
1202 {
1203         return _region_start + region_length();
1204 }
1205
1206 void
1207 WaveView::set_region_start (frameoffset_t start)
1208 {
1209         if (!_region) {
1210                 return;
1211         }
1212
1213         if (_region_start == start) {
1214                 return;
1215         }
1216
1217         begin_change ();
1218         _region_start = start;
1219         _bounding_box_dirty = true;
1220         end_change ();
1221 }
1222
1223 void
1224 WaveView::region_resized ()
1225 {
1226         /* Called when the region start or end (thus length) has changed.
1227         */
1228
1229         if (!_region) {
1230                 return;
1231         }
1232
1233         begin_change ();
1234         _region_start = _region->start();
1235         _bounding_box_dirty = true;
1236         end_change ();
1237 }
1238
1239 void
1240 WaveView::set_global_gradient_depth (double depth)
1241 {
1242         if (_global_gradient_depth != depth) {
1243                 _global_gradient_depth = depth;
1244                 VisualPropertiesChanged (); /* EMIT SIGNAL */
1245         }
1246 }
1247
1248 void
1249 WaveView::set_global_show_waveform_clipping (bool yn)
1250 {
1251         if (_global_show_waveform_clipping != yn) {
1252                 _global_show_waveform_clipping = yn;
1253                 ClipLevelChanged ();
1254         }
1255 }
1256
1257 void
1258 WaveView::set_start_shift (double pixels)
1259 {
1260         if (pixels < 0) {
1261                 return;
1262         }
1263
1264         begin_visual_change ();
1265         _start_shift = pixels;
1266         end_visual_change ();
1267 }
1268
1269
1270 void
1271 WaveView::cancel_my_render_request () const
1272 {
1273         if (!images) {
1274                 return;
1275         }
1276
1277         /* try to stop any current rendering of the request, or prevent it from
1278          * ever starting up.
1279          */
1280
1281         if (current_request) {
1282                 current_request->cancel ();
1283         }
1284
1285         Glib::Threads::Mutex::Lock lm (request_queue_lock);
1286
1287         /* now remove it from the queue and reset our request pointer so that
1288            have no outstanding request (that we know about)
1289         */
1290
1291         request_queue.erase (this);
1292         current_request.reset ();
1293 }
1294
1295 void
1296 WaveView::send_request (boost::shared_ptr<WaveViewThreadRequest> req) const
1297 {
1298         if (req->type == WaveViewThreadRequest::Draw && current_request) {
1299                 /* this will stop rendering in progress (which might otherwise
1300                    be long lived) for any current request.
1301                 */
1302                 current_request->cancel ();
1303         }
1304
1305         start_drawing_thread ();
1306
1307         Glib::signal_idle().connect (sigc::bind (sigc::mem_fun (this, &WaveView::idle_send_request), req));
1308 }
1309
1310 bool
1311 WaveView::idle_send_request (boost::shared_ptr<WaveViewThreadRequest> req) const
1312 {
1313         {
1314                 Glib::Threads::Mutex::Lock lm (request_queue_lock);
1315                 /* swap requests (protected by lock) */
1316                 current_request = req;
1317                 request_queue.insert (this);
1318         }
1319
1320         request_cond.signal (); /* wake thread */
1321
1322         return false; /* do not call from idle again */
1323 }
1324
1325 /*-------------------------------------------------*/
1326
1327 void
1328 WaveView::start_drawing_thread ()
1329 {
1330         if (!_drawing_thread) {
1331                 _drawing_thread = Glib::Threads::Thread::create (sigc::ptr_fun (WaveView::drawing_thread));
1332         }
1333 }
1334
1335 void
1336 WaveView::stop_drawing_thread ()
1337 {
1338         if (_drawing_thread) {
1339                 Glib::Threads::Mutex::Lock lm (request_queue_lock);
1340                 g_atomic_int_set (&drawing_thread_should_quit, 1);
1341                 request_cond.signal ();
1342         }
1343 }
1344
1345 void
1346 WaveView::drawing_thread ()
1347 {
1348         using namespace Glib::Threads;
1349
1350         WaveView const * requestor;
1351         Mutex::Lock lm (request_queue_lock);
1352         bool run = true;
1353
1354         while (run) {
1355
1356                 /* remember that we hold the lock at this point, no matter what */
1357
1358                 if (g_atomic_int_get (&drawing_thread_should_quit)) {
1359                         break;
1360                 }
1361
1362                 if (request_queue.empty()) {
1363                         request_cond.wait (request_queue_lock);
1364                 }
1365
1366                 /* remove the request from the queue (remember: the "request"
1367                  * is just a pointer to a WaveView object)
1368                  */
1369
1370                 requestor = *(request_queue.begin());
1371                 request_queue.erase (request_queue.begin());
1372
1373                 boost::shared_ptr<WaveViewThreadRequest> req = requestor->current_request;
1374
1375                 if (!req) {
1376                         continue;
1377                 }
1378
1379                 /* Generate an image. Unlock the request queue lock
1380                  * while we do this, so that other things can happen
1381                  * as we do rendering.
1382                  */
1383
1384                 request_queue_lock.unlock (); /* some RAII would be good here */
1385
1386                 try {
1387                         requestor->generate_image (req, true);
1388                 } catch (...) {
1389                         req->image.clear(); /* just in case it was set before the exception, whatever it was */
1390                 }
1391
1392                 request_queue_lock.lock ();
1393
1394                 req.reset (); /* drop/delete request as appropriate */
1395         }
1396
1397         /* thread is vanishing */
1398         _drawing_thread = 0;
1399 }
1400
1401 /*-------------------------------------------------*/
1402
1403 WaveViewCache::WaveViewCache ()
1404         : image_cache_size (0)
1405         , _image_cache_threshold (100 * 1048576) /* bytes */
1406 {
1407 }
1408
1409 WaveViewCache::~WaveViewCache ()
1410 {
1411 }
1412
1413
1414 boost::shared_ptr<WaveViewCache::Entry>
1415 WaveViewCache::lookup_image (boost::shared_ptr<ARDOUR::AudioSource> src,
1416                              framepos_t start, framepos_t end,
1417                              int channel,
1418                              Coord height,
1419                              float amplitude,
1420                              Color fill_color,
1421                              double samples_per_pixel)
1422 {
1423         ImageCache::iterator x;
1424
1425         if ((x = cache_map.find (src)) == cache_map.end ()) {
1426                 /* nothing in the cache for this audio source at all */
1427                 return boost::shared_ptr<WaveViewCache::Entry> ();
1428         }
1429
1430         CacheLine& caches = x->second;
1431
1432         /* Find a suitable ImageSurface, if it exists.
1433         */
1434
1435         for (CacheLine::iterator c = caches.begin(); c != caches.end(); ++c) {
1436
1437                 boost::shared_ptr<Entry> e (*c);
1438
1439                 if (channel != e->channel
1440                     || height != e->height
1441                     || amplitude != e->amplitude
1442                     || samples_per_pixel != e->samples_per_pixel
1443                     || fill_color != e->fill_color) {
1444                         continue;
1445                 }
1446
1447                 if (end <= e->end && start >= e->start) {
1448                         /* found an image that covers the range we need */
1449                         use (src, e);
1450                         return e;
1451                 }
1452         }
1453
1454         return boost::shared_ptr<Entry> ();
1455 }
1456
1457 void
1458 WaveViewCache::consolidate_image_cache (boost::shared_ptr<ARDOUR::AudioSource> src,
1459                                         int channel,
1460                                         Coord height,
1461                                         float amplitude,
1462                                         Color fill_color,
1463                                         double samples_per_pixel)
1464 {
1465         list <uint32_t> deletion_list;
1466         uint32_t other_entries = 0;
1467         ImageCache::iterator x;
1468
1469         /* MUST BE CALLED FROM (SINGLE) GUI THREAD */
1470
1471         if ((x = cache_map.find (src)) == cache_map.end ()) {
1472                 return;
1473         }
1474
1475         CacheLine& caches  = x->second;
1476
1477         for (CacheLine::iterator c1 = caches.begin(); c1 != caches.end(); ) {
1478
1479                 CacheLine::iterator nxt = c1;
1480                 ++nxt;
1481
1482                 boost::shared_ptr<Entry> e1 (*c1);
1483
1484                 if (channel != e1->channel
1485                     || height != e1->height
1486                     || amplitude != e1->amplitude
1487                     || samples_per_pixel != e1->samples_per_pixel
1488                     || fill_color != e1->fill_color) {
1489
1490                         /* doesn't match current properties, ignore and move on
1491                          * to the next one.
1492                          */
1493
1494                         other_entries++;
1495                         c1 = nxt;
1496                         continue;
1497                 }
1498
1499                 /* c1 now points to a cached image entry that matches current
1500                  * properties. Check all subsequent cached imaged entries to
1501                  * see if there are others that also match but represent
1502                  * subsets of the range covered by this one.
1503                  */
1504
1505                 for (CacheLine::iterator c2 = c1; c2 != caches.end(); ) {
1506
1507                         CacheLine::iterator nxt2 = c2;
1508                         ++nxt2;
1509
1510                         boost::shared_ptr<Entry> e2 (*c2);
1511
1512                         if (e1 == e2 || channel != e2->channel
1513                             || height != e2->height
1514                             || amplitude != e2->amplitude
1515                             || samples_per_pixel != e2->samples_per_pixel
1516                             || fill_color != e2->fill_color) {
1517
1518                                 /* properties do not match, ignore for the
1519                                  * purposes of consolidation.
1520                                  */
1521                                 c2 = nxt2;
1522                                 continue;
1523                         }
1524
1525                         if (e2->start >= e1->start && e2->end <= e1->end) {
1526                                 /* c2 is fully contained by c1, so delete it */
1527                                 c2 = caches.erase (c2);
1528                                 continue;
1529                         }
1530
1531                         c2 = nxt2;
1532                 }
1533
1534                 c1 = nxt;
1535         }
1536 }
1537
1538 void
1539 WaveViewCache::use (boost::shared_ptr<ARDOUR::AudioSource> src, boost::shared_ptr<Entry> ce)
1540 {
1541         ce->timestamp = g_get_monotonic_time ();
1542 }
1543
1544 void
1545 WaveViewCache::add (boost::shared_ptr<ARDOUR::AudioSource> src, boost::shared_ptr<Entry> ce)
1546 {
1547         /* MUST BE CALLED FROM (SINGLE) GUI THREAD */
1548
1549         Cairo::RefPtr<Cairo::ImageSurface> img (ce->image);
1550
1551         image_cache_size += img->get_height() * img->get_width () * 4; /* 4 = bytes per FORMAT_ARGB32 pixel */
1552
1553         if (cache_full()) {
1554                 cache_flush ();
1555         }
1556
1557         ce->timestamp = g_get_monotonic_time ();
1558
1559         cache_map[src].push_back (ce);
1560         cache_list.push_back (make_pair (src, ce));
1561 }
1562
1563 uint64_t
1564 WaveViewCache::compute_image_cache_size()
1565 {
1566         uint64_t total = 0;
1567         for (ImageCache::iterator s = cache_map.begin(); s != cache_map.end(); ++s) {
1568                 CacheLine& per_source_cache (s->second);
1569                 for (CacheLine::iterator c = per_source_cache.begin(); c != per_source_cache.end(); ++c) {
1570                         Cairo::RefPtr<Cairo::ImageSurface> img ((*c)->image);
1571                         total += img->get_height() * img->get_width() * 4; /* 4 = bytes per FORMAT_ARGB32 pixel */
1572                 }
1573         }
1574         return total;
1575 }
1576
1577 bool
1578 WaveViewCache::cache_full()
1579 {
1580         return image_cache_size > _image_cache_threshold;
1581 }
1582
1583 void
1584 WaveViewCache::cache_flush ()
1585 {
1586         SortByTimestamp sorter;
1587
1588         /* sort list in LRU order */
1589
1590         sort (cache_list.begin(), cache_list.end(), sorter);
1591
1592         while (image_cache_size > _image_cache_threshold) {
1593
1594                 ListEntry& le (cache_list.front());
1595
1596                 ImageCache::iterator x;
1597
1598                 if ((x = cache_map.find (le.first)) == cache_map.end ()) {
1599                         /* wierd ... no entry for this AudioSource */
1600                         continue;
1601                 }
1602
1603                 CacheLine& cl  = x->second;
1604
1605                 for (CacheLine::iterator c = cl.begin(); c != cl.end(); ++c) {
1606
1607                         if (*c == le.second) {
1608
1609                                 /* Remove this entry from this cache line */
1610                                 cl.erase (c);
1611
1612                                 if (cl.empty()) {
1613                                         /* remove cache line from main cache: no more entries */
1614                                         cache_map.erase (x);
1615                                 }
1616
1617                                 break;
1618                         }
1619                 }
1620
1621                 Cairo::RefPtr<Cairo::ImageSurface> img (le.second->image);
1622                 uint64_t size = img->get_height() * img->get_width() * 4; /* 4 = bytes per FORMAT_ARGB32 pixel */
1623
1624                 if (image_cache_size > size) {
1625                         image_cache_size -= size;
1626                 } else {
1627                         image_cache_size = 0;
1628                 }
1629
1630                 /* Remove from the linear list */
1631                 cache_list.erase (cache_list.begin());
1632         }
1633 }
1634
1635 void
1636 WaveViewCache::set_image_cache_threshold (uint64_t sz)
1637 {
1638         _image_cache_threshold = sz;
1639         cache_flush ();
1640 }