git.sesse.net Git - nageru/blob - mainwindow.cpp

   1 #include "mainwindow.h"
   2
   3 #include <math.h>
   4 #include <stdio.h>
   5 #include <signal.h>
   6 #include <algorithm>
   7 #include <chrono>
   8 #include <string>
   9 #include <vector>
  10 #include <QBoxLayout>
  11 #include <QInputDialog>
  12 #include <QKeySequence>
  13 #include <QLabel>
  14 #include <QMetaType>
  15 #include <QPushButton>
  16 #include <QResizeEvent>
  17 #include <QShortcut>
  18 #include <QSize>
  19 #include <QString>
  20
  21 #include "aboutdialog.h"
  22 #include "disk_space_estimator.h"
  23 #include "flags.h"
  24 #include "glwidget.h"
  25 #include "lrameter.h"
  26 #include "mixer.h"
  27 #include "post_to_main_thread.h"
  28 #include "ui_audio_miniview.h"
  29 #include "ui_display.h"
  30 #include "ui_mainwindow.h"
  31 #include "vumeter.h"
  32
  33 class QResizeEvent;
  34
  35 using namespace std;
  36 using namespace std::chrono;
  37 using namespace std::placeholders;
  38
  39 Q_DECLARE_METATYPE(std::string);
  40 Q_DECLARE_METATYPE(std::vector<std::string>);
  41
  42 MainWindow *global_mainwindow = nullptr;
  43
  44 namespace {
  45
  46 void schedule_cut_signal(int ignored)
  47 {
  48         global_mixer->schedule_cut();
  49 }
  50
  51 void quit_signal(int ignored)
  52 {
  53         global_mainwindow->close();
  54 }
  55
  56 constexpr unsigned DB_NO_FLAGS = 0x0;
  57 constexpr unsigned DB_WITH_SIGN = 0x1;
  58 constexpr unsigned DB_BARE = 0x2;
  59
  60 string format_db(double db, unsigned flags)
  61 {
  62         string text;
  63         if (flags & DB_WITH_SIGN) {
  64                 if (isfinite(db)) {
  65                         char buf[256];
  66                         snprintf(buf, sizeof(buf), "%+.1f", db);
  67                         text = buf;
  68                 } else if (db < 0.0) {
  69                         text = "-∞";
  70                 } else {
  71                         // Should never happen, really.
  72                         text = "+∞";
  73                 }
  74         } else {
  75                 if (isfinite(db)) {
  76                         char buf[256];
  77                         snprintf(buf, sizeof(buf), "%.1f", db);
  78                         text = buf;
  79                 } else if (db < 0.0) {
  80                         text = "-∞";
  81                 } else {
  82                         // Should never happen, really.
  83                         text = "∞";
  84                 }
  85         }
  86         if (!(flags & DB_BARE)) {
  87                 text += " dB";
  88         }
  89         return text;
  90 }
  91
  92 }  // namespace
  93
  94 MainWindow::MainWindow()
  95         : ui(new Ui::MainWindow)
  96 {
  97         global_mainwindow = this;
  98         ui->setupUi(this);
  99
 100         global_disk_space_estimator = new DiskSpaceEstimator(bind(&MainWindow::report_disk_space, this, _1, _2));
 101         disk_free_label = new QLabel(this);
 102         disk_free_label->setStyleSheet("QLabel {padding-right: 5px;}");
 103         ui->menuBar->setCornerWidget(disk_free_label);
 104
 105         ui->me_live->set_output(Mixer::OUTPUT_LIVE);
 106         ui->me_preview->set_output(Mixer::OUTPUT_PREVIEW);
 107
 108         // The menus.
 109         connect(ui->cut_action, &QAction::triggered, this, &MainWindow::cut_triggered);
 110         connect(ui->exit_action, &QAction::triggered, this, &MainWindow::exit_triggered);
 111         connect(ui->about_action, &QAction::triggered, this, &MainWindow::about_triggered);
 112
 113         if (global_flags.x264_video_to_http) {
 114                 connect(ui->x264_bitrate_action, &QAction::triggered, this, &MainWindow::x264_bitrate_triggered);
 115         } else {
 116                 ui->x264_bitrate_action->setEnabled(false);
 117         }
 118
 119         // Hook up the transition buttons. (Keyboard shortcuts are set in set_transition_names().)
 120         // TODO: Make them dynamic.
 121         connect(ui->transition_btn1, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 0));
 122         connect(ui->transition_btn2, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 1));
 123         connect(ui->transition_btn3, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 2));
 124
 125         // Aiee...
 126         transition_btn1 = ui->transition_btn1;
 127         transition_btn2 = ui->transition_btn2;
 128         transition_btn3 = ui->transition_btn3;
 129         qRegisterMetaType<string>("std::string");
 130         qRegisterMetaType<vector<string>>("std::vector<std::string>");
 131         connect(ui->me_live, &GLWidget::transition_names_updated, this, &MainWindow::set_transition_names);
 132         qRegisterMetaType<Mixer::Output>("Mixer::Output");
 133
 134         last_audio_level_callback = steady_clock::now() - seconds(1);
 135 }
 136
 137 void MainWindow::resizeEvent(QResizeEvent* event)
 138 {
 139         QMainWindow::resizeEvent(event);
 140
 141         // Ask for a relayout, but only after the event loop is done doing relayout
 142         // on everything else.
 143         QMetaObject::invokeMethod(this, "relayout", Qt::QueuedConnection);
 144 }
 145
 146 void MainWindow::mixer_created(Mixer *mixer)
 147 {
 148         // Make the previews.
 149         unsigned num_previews = mixer->get_num_channels();
 150
 151         for (unsigned i = 0; i < num_previews; ++i) {
 152                 Mixer::Output output = Mixer::Output(Mixer::OUTPUT_INPUT0 + i);
 153
 154                 QWidget *preview = new QWidget(this);
 155                 Ui::Display *ui_display = new Ui::Display;
 156                 ui_display->setupUi(preview);
 157                 ui_display->label->setText(mixer->get_channel_name(output).c_str());
 158                 ui_display->display->set_output(output);
 159                 ui->preview_displays->insertWidget(previews.size(), preview, 1);
 160                 previews.push_back(ui_display);
 161
 162                 // Hook up the click.
 163                 connect(ui_display->display, &GLWidget::clicked, bind(&MainWindow::channel_clicked, this, i));
 164
 165                 // Let the theme update the text whenever the resolution or color changed.
 166                 connect(ui_display->display, &GLWidget::name_updated, this, &MainWindow::update_channel_name);
 167                 connect(ui_display->display, &GLWidget::color_updated, this, &MainWindow::update_channel_color);
 168
 169                 // Hook up the keyboard key.
 170                 QShortcut *shortcut = new QShortcut(QKeySequence(Qt::Key_1 + i), this);
 171                 connect(shortcut, &QShortcut::activated, bind(&MainWindow::channel_clicked, this, i));
 172
 173                 // Hook up the white balance button (irrelevant if invisible).
 174                 ui_display->wb_button->setVisible(mixer->get_supports_set_wb(output));
 175                 connect(ui_display->wb_button, &QPushButton::clicked, bind(&MainWindow::wb_button_clicked, this, i));
 176         }
 177
 178         // Audio miniview: Make some channels!
 179         for (unsigned i = 0; i < num_previews; ++i) {
 180                 Mixer::Output output = Mixer::Output(Mixer::OUTPUT_INPUT0 + i);
 181
 182                 QWidget *channel = new QWidget(this);
 183                 Ui::AudioMiniView *ui_audio_miniview = new Ui::AudioMiniView;
 184                 ui_audio_miniview->setupUi(channel);
 185                 ui_audio_miniview->channel_desc_label->setFullText(
 186                         QString::fromStdString(mixer->get_channel_name(output)));
 187                 ui->faders->addWidget(channel);
 188
 189                 connect(ui_audio_miniview->fader, &QAbstractSlider::valueChanged,
 190                         bind(&MainWindow::mini_fader_changed, this, ui_audio_miniview, i, _1));
 191         }
 192
 193         // TODO: Fetch all of the values these for completeness,
 194         // not just the enable knobs implied by flags.
 195         ui->locut_enabled->setChecked(global_mixer->get_audio_mixer()->get_locut_enabled());
 196         ui->gainstaging_knob->setValue(global_mixer->get_audio_mixer()->get_gain_staging_db());
 197         ui->gainstaging_auto_checkbox->setChecked(global_mixer->get_audio_mixer()->get_gain_staging_auto());
 198         ui->compressor_enabled->setChecked(global_mixer->get_audio_mixer()->get_compressor_enabled());
 199         ui->limiter_enabled->setChecked(global_mixer->get_audio_mixer()->get_limiter_enabled());
 200         ui->makeup_gain_auto_checkbox->setChecked(global_mixer->get_audio_mixer()->get_final_makeup_gain_auto());
 201
 202         ui->limiter_threshold_db_display->setText(
 203                 QString::fromStdString(format_db(mixer->get_audio_mixer()->get_limiter_threshold_dbfs(), DB_WITH_SIGN)));
 204         ui->compressor_threshold_db_display->setText(
 205                 QString::fromStdString(format_db(mixer->get_audio_mixer()->get_compressor_threshold_dbfs(), DB_WITH_SIGN)));
 206
 207         connect(ui->locut_cutoff_knob, &QDial::valueChanged, this, &MainWindow::cutoff_knob_changed);
 208         cutoff_knob_changed(ui->locut_cutoff_knob->value());
 209         connect(ui->locut_enabled, &QCheckBox::stateChanged, [this](int state){
 210                 global_mixer->get_audio_mixer()->set_locut_enabled(state == Qt::Checked);
 211         });
 212
 213         connect(ui->gainstaging_knob, &QAbstractSlider::valueChanged, this, &MainWindow::gain_staging_knob_changed);
 214         connect(ui->gainstaging_auto_checkbox, &QCheckBox::stateChanged, [this](int state){
 215                 global_mixer->get_audio_mixer()->set_gain_staging_auto(state == Qt::Checked);
 216         });
 217         connect(ui->makeup_gain_knob, &QAbstractSlider::valueChanged, this, &MainWindow::final_makeup_gain_knob_changed);
 218         connect(ui->makeup_gain_auto_checkbox, &QCheckBox::stateChanged, [this](int state){
 219                 global_mixer->get_audio_mixer()->set_final_makeup_gain_auto(state == Qt::Checked);
 220         });
 221
 222         connect(ui->limiter_threshold_knob, &QDial::valueChanged, this, &MainWindow::limiter_threshold_knob_changed);
 223         connect(ui->compressor_threshold_knob, &QDial::valueChanged, this, &MainWindow::compressor_threshold_knob_changed);
 224         connect(ui->limiter_enabled, &QCheckBox::stateChanged, [this](int state){
 225                 global_mixer->get_audio_mixer()->set_limiter_enabled(state == Qt::Checked);
 226         });
 227         connect(ui->compressor_enabled, &QCheckBox::stateChanged, [this](int state){
 228                 global_mixer->get_audio_mixer()->set_compressor_enabled(state == Qt::Checked);
 229         });
 230         connect(ui->reset_meters_button, &QPushButton::clicked, this, &MainWindow::reset_meters_button_clicked);
 231         mixer->set_audio_level_callback(bind(&MainWindow::audio_level_callback, this, _1, _2, _3, _4, _5, _6, _7, _8));
 232
 233         struct sigaction act;
 234         memset(&act, 0, sizeof(act));
 235         act.sa_handler = schedule_cut_signal;
 236         act.sa_flags = SA_RESTART;
 237         sigaction(SIGHUP, &act, nullptr);
 238
 239         // Mostly for debugging. Don't override SIGINT, that's so evil if
 240         // shutdown isn't instant.
 241         memset(&act, 0, sizeof(act));
 242         act.sa_handler = quit_signal;
 243         act.sa_flags = SA_RESTART;
 244         sigaction(SIGUSR1, &act, nullptr);
 245 }
 246
 247 void MainWindow::mixer_shutting_down()
 248 {
 249         ui->me_live->clean_context();
 250         ui->me_preview->clean_context();
 251         for (Ui::Display *display : previews) {
 252                 display->display->clean_context();
 253         }
 254 }
 255
 256 void MainWindow::cut_triggered()
 257 {
 258         global_mixer->schedule_cut();
 259 }
 260
 261 void MainWindow::x264_bitrate_triggered()
 262 {
 263         bool ok;
 264         int new_bitrate = QInputDialog::getInt(this, "Change x264 bitrate", "Choose new bitrate for x264 HTTP output (from 100–100,000 kbit/sec):", global_flags.x264_bitrate, /*min=*/100, /*max=*/100000, /*step=*/100, &ok);
 265         if (ok && new_bitrate >= 100 && new_bitrate <= 100000) {
 266                 global_flags.x264_bitrate = new_bitrate;
 267                 global_mixer->change_x264_bitrate(new_bitrate);
 268         }
 269 }
 270
 271 void MainWindow::exit_triggered()
 272 {
 273         close();
 274 }
 275
 276 void MainWindow::about_triggered()
 277 {
 278         AboutDialog().exec();
 279 }
 280
 281 void MainWindow::gain_staging_knob_changed(int value)
 282 {
 283         ui->gainstaging_auto_checkbox->setCheckState(Qt::Unchecked);
 284
 285         float gain_db = value * 0.1f;
 286         global_mixer->get_audio_mixer()->set_gain_staging_db(gain_db);
 287
 288         // The label will be updated by the audio level callback.
 289 }
 290
 291 void MainWindow::final_makeup_gain_knob_changed(int value)
 292 {
 293         ui->makeup_gain_auto_checkbox->setCheckState(Qt::Unchecked);
 294
 295         float gain_db = value * 0.1f;
 296         global_mixer->get_audio_mixer()->set_final_makeup_gain_db(gain_db);
 297
 298         // The label will be updated by the audio level callback.
 299 }
 300
 301 void MainWindow::cutoff_knob_changed(int value)
 302 {
 303         float octaves = value * 0.1f;
 304         float cutoff_hz = 20.0 * pow(2.0, octaves);
 305         global_mixer->get_audio_mixer()->set_locut_cutoff(cutoff_hz);
 306
 307         char buf[256];
 308         snprintf(buf, sizeof(buf), "%ld Hz", lrintf(cutoff_hz));
 309         ui->locut_cutoff_display->setText(buf);
 310 }
 311
 312 void MainWindow::report_disk_space(off_t free_bytes, double estimated_seconds_left)
 313 {
 314         char time_str[256];
 315         if (estimated_seconds_left < 60.0) {
 316                 strcpy(time_str, "<font color=\"red\">Less than a minute</font>");
 317         } else if (estimated_seconds_left < 1800.0) {  // Less than half an hour: Xm Ys (red).
 318                 int s = lrintf(estimated_seconds_left);
 319                 int m = s / 60;
 320                 s %= 60;
 321                 snprintf(time_str, sizeof(time_str), "<font color=\"red\">%dm %ds</font>", m, s);
 322         } else if (estimated_seconds_left < 3600.0) {  // Less than an hour: Xm.
 323                 int m = lrintf(estimated_seconds_left / 60.0);
 324                 snprintf(time_str, sizeof(time_str), "%dm", m);
 325         } else if (estimated_seconds_left < 36000.0) {  // Less than ten hours: Xh Ym.
 326                 int m = lrintf(estimated_seconds_left / 60.0);
 327                 int h = m / 60;
 328                 m %= 60;
 329                 snprintf(time_str, sizeof(time_str), "%dh %dm", h, m);
 330         } else {  // More than ten hours: Xh.
 331                 int h = lrintf(estimated_seconds_left / 3600.0);
 332                 snprintf(time_str, sizeof(time_str), "%dh", h);
 333         }
 334         char buf[256];
 335         snprintf(buf, sizeof(buf), "Disk free: %'.0f MB (approx. %s)", free_bytes / 1048576.0, time_str);
 336
 337         std::string label = buf;
 338
 339         post_to_main_thread([this, label]{
 340                 disk_free_label->setText(QString::fromStdString(label));
 341                 ui->menuBar->setCornerWidget(disk_free_label);  // Need to set this again for the sizing to get right.
 342         });
 343 }
 344
 345 void MainWindow::limiter_threshold_knob_changed(int value)
 346 {
 347         float threshold_dbfs = value * 0.1f;
 348         global_mixer->get_audio_mixer()->set_limiter_threshold_dbfs(threshold_dbfs);
 349         ui->limiter_threshold_db_display->setText(
 350                 QString::fromStdString(format_db(threshold_dbfs, DB_WITH_SIGN)));
 351 }
 352
 353 void MainWindow::compressor_threshold_knob_changed(int value)
 354 {
 355         float threshold_dbfs = value * 0.1f;
 356         global_mixer->get_audio_mixer()->set_compressor_threshold_dbfs(threshold_dbfs);
 357         ui->compressor_threshold_db_display->setText(
 358                 QString::fromStdString(format_db(threshold_dbfs, DB_WITH_SIGN)));
 359 }
 360
 361 void MainWindow::mini_fader_changed(Ui::AudioMiniView *ui, int channel, int value)
 362 {
 363         float volume_db = value * 0.1f;
 364
 365         char buf[256];
 366         snprintf(buf, sizeof(buf), "%+.1f dB", volume_db);
 367         ui->fader_label->setText(buf);
 368
 369         global_mixer->get_audio_mixer()->set_fader_volume(channel, volume_db);
 370 }
 371
 372 void MainWindow::reset_meters_button_clicked()
 373 {
 374         global_mixer->reset_meters();
 375         ui->peak_display->setText(QString::fromStdString(format_db(-HUGE_VAL, DB_WITH_SIGN | DB_BARE)));
 376         ui->peak_display->setStyleSheet("");
 377 }
 378
 379 void MainWindow::audio_level_callback(float level_lufs, float peak_db, float global_level_lufs,
 380                                       float range_low_lufs, float range_high_lufs,
 381                                       float gain_staging_db, float final_makeup_gain_db,
 382                                       float correlation)
 383 {
 384         steady_clock::time_point now = steady_clock::now();
 385
 386         // The meters are somewhat inefficient to update. Only update them
 387         // every 100 ms or so (we get updates every 5–20 ms).
 388         double last_update_age = duration<double>(now - last_audio_level_callback).count();
 389         if (last_update_age < 0.100) {
 390                 return;
 391         }
 392         last_audio_level_callback = now;
 393
 394         post_to_main_thread([=]() {
 395                 ui->vu_meter->set_level(level_lufs);
 396                 ui->lra_meter->set_levels(global_level_lufs, range_low_lufs, range_high_lufs);
 397                 ui->correlation_meter->set_correlation(correlation);
 398
 399                 ui->peak_display->setText(QString::fromStdString(format_db(peak_db, DB_BARE)));
 400                 if (peak_db > -0.1f) {  // -0.1 dBFS is EBU peak limit.
 401                         ui->peak_display->setStyleSheet("QLabel { background-color: red; color: white; }");
 402                 } else {
 403                         ui->peak_display->setStyleSheet("");
 404                 }
 405
 406                 ui->gainstaging_knob->blockSignals(true);
 407                 ui->gainstaging_knob->setValue(lrintf(gain_staging_db * 10.0f));
 408                 ui->gainstaging_knob->blockSignals(false);
 409                 ui->gainstaging_db_display->setText(
 410                         QString::fromStdString(format_db(gain_staging_db, DB_WITH_SIGN)));
 411
 412                 ui->makeup_gain_knob->blockSignals(true);
 413                 ui->makeup_gain_knob->setValue(lrintf(final_makeup_gain_db * 10.0f));
 414                 ui->makeup_gain_knob->blockSignals(false);
 415                 ui->makeup_gain_db_display->setText(
 416                         QString::fromStdString(format_db(final_makeup_gain_db, DB_WITH_SIGN)));
 417         });
 418 }
 419
 420 void MainWindow::relayout()
 421 {
 422         int height = ui->vertical_layout->geometry().height();
 423
 424         double remaining_height = height;
 425
 426         // Allocate the height; the most important part is to keep the main displays
 427         // at 16:9 if at all possible.
 428         double me_width = ui->me_preview->width();
 429         double me_height = me_width * 9.0 / 16.0 + ui->label_preview->height() + ui->preview_vertical_layout->spacing();
 430
 431         // TODO: Scale the widths when we need to do this.
 432         if (me_height / double(height) > 0.8) {
 433                 me_height = height * 0.8;
 434         }
 435         remaining_height -= me_height + ui->vertical_layout->spacing();
 436
 437         // Space between the M/E displays and the audio strip.
 438         remaining_height -= ui->vertical_layout->spacing();
 439
 440         // The previews will be constrained by the remaining height, and the width.
 441         double preview_label_height = previews[0]->title_bar->geometry().height() +
 442                 previews[0]->main_vertical_layout->spacing();
 443         int preview_total_width = ui->preview_displays->geometry().width() - (previews.size() - 1) * ui->preview_displays->spacing();
 444         double preview_height = min(remaining_height - preview_label_height, (preview_total_width / double(previews.size())) * 9.0 / 16.0);
 445         remaining_height -= preview_height + preview_label_height + ui->vertical_layout->spacing();
 446
 447         ui->vertical_layout->setStretch(0, lrintf(me_height));
 448         ui->vertical_layout->setStretch(1, lrintf(remaining_height));  // Audio strip.
 449         ui->vertical_layout->setStretch(2, lrintf(preview_height + preview_label_height));
 450
 451         // Set the widths for the previews.
 452         double preview_width = preview_height * 16.0 / 9.0;
 453         for (unsigned i = 0; i < previews.size(); ++i) {
 454                 ui->preview_displays->setStretch(i, lrintf(preview_width));
 455         }
 456
 457         // The preview horizontal spacer.
 458         double remaining_preview_width = preview_total_width - previews.size() * preview_width;
 459         ui->preview_displays->setStretch(previews.size(), lrintf(remaining_preview_width));
 460 }
 461
 462 void MainWindow::set_transition_names(vector<string> transition_names)
 463 {
 464         if (transition_names.size() < 1 || transition_names[0].empty()) {
 465                 transition_btn1->setText(QString(""));
 466         } else {
 467                 transition_btn1->setText(QString::fromStdString(transition_names[0] + " (J)"));
 468                 ui->transition_btn1->setShortcut(QKeySequence("J"));
 469         }
 470         if (transition_names.size() < 2 || transition_names[1].empty()) {
 471                 transition_btn2->setText(QString(""));
 472         } else {
 473                 transition_btn2->setText(QString::fromStdString(transition_names[1] + " (K)"));
 474                 ui->transition_btn2->setShortcut(QKeySequence("K"));
 475         }
 476         if (transition_names.size() < 3 || transition_names[2].empty()) {
 477                 transition_btn3->setText(QString(""));
 478         } else {
 479                 transition_btn3->setText(QString::fromStdString(transition_names[2] + " (L)"));
 480                 ui->transition_btn3->setShortcut(QKeySequence("L"));
 481         }
 482 }
 483
 484 void MainWindow::update_channel_name(Mixer::Output output, const string &name)
 485 {
 486         if (output >= Mixer::OUTPUT_INPUT0) {
 487                 unsigned channel = output - Mixer::OUTPUT_INPUT0;
 488                 previews[channel]->label->setText(name.c_str());
 489         }
 490 }
 491
 492 void MainWindow::update_channel_color(Mixer::Output output, const string &color)
 493 {
 494         if (output >= Mixer::OUTPUT_INPUT0) {
 495                 unsigned channel = output - Mixer::OUTPUT_INPUT0;
 496                 previews[channel]->frame->setStyleSheet(QString::fromStdString("background-color:" + color));
 497         }
 498 }
 499
 500 void MainWindow::transition_clicked(int transition_number)
 501 {
 502         global_mixer->transition_clicked(transition_number);
 503 }
 504
 505 void MainWindow::channel_clicked(int channel_number)
 506 {
 507         if (current_wb_pick_display == channel_number) {
 508                 // The picking was already done from eventFilter(), since we don't get
 509                 // the mouse pointer here.
 510         } else {
 511                 global_mixer->channel_clicked(channel_number);
 512         }
 513 }
 514
 515 void MainWindow::wb_button_clicked(int channel_number)
 516 {
 517         current_wb_pick_display = channel_number;
 518         QApplication::setOverrideCursor(Qt::CrossCursor);
 519 }
 520
 521 bool MainWindow::eventFilter(QObject *watched, QEvent *event)
 522 {
 523         if (current_wb_pick_display != -1 &&
 524             event->type() == QEvent::MouseButtonRelease &&
 525             watched->isWidgetType()) {
 526                 QApplication::restoreOverrideCursor();
 527                 if (watched == previews[current_wb_pick_display]->display) {
 528                         const QMouseEvent *mouse_event = (QMouseEvent *)event;
 529                         set_white_balance(current_wb_pick_display, mouse_event->x(), mouse_event->y());
 530                 } else {
 531                         // The user clicked on something else, give up.
 532                         // (The click goes through, which might not be ideal, but, yes.)
 533                         current_wb_pick_display = -1;
 534                 }
 535         }
 536         return false;
 537 }
 538
 539 namespace {
 540
 541 double srgb_to_linear(double x)
 542 {
 543         if (x < 0.04045) {
 544                 return x / 12.92;
 545         } else {
 546                 return pow((x + 0.055) / 1.055, 2.4);
 547         }
 548 }
 549
 550 }  // namespace
 551
 552 void MainWindow::set_white_balance(int channel_number, int x, int y)
 553 {
 554         // Set the white balance to neutral for the grab. It's probably going to
 555         // flicker a bit, but hopefully this display is not live anyway.
 556         global_mixer->set_wb(Mixer::OUTPUT_INPUT0 + channel_number, 0.5, 0.5, 0.5);
 557         previews[channel_number]->display->updateGL();
 558         QRgb reference_color = previews[channel_number]->display->grabFrameBuffer().pixel(x, y);
 559
 560         double r = srgb_to_linear(qRed(reference_color) / 255.0);
 561         double g = srgb_to_linear(qGreen(reference_color) / 255.0);
 562         double b = srgb_to_linear(qBlue(reference_color) / 255.0);
 563         global_mixer->set_wb(Mixer::OUTPUT_INPUT0 + channel_number, r, g, b);
 564         previews[channel_number]->display->updateGL();
 565 }