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 "input_mapping_dialog.h"
  26 #include "lrameter.h"
  27 #include "mixer.h"
  28 #include "post_to_main_thread.h"
  29 #include "ui_audio_miniview.h"
  30 #include "ui_display.h"
  31 #include "ui_mainwindow.h"
  32 #include "vumeter.h"
  33
  34 class QResizeEvent;
  35
  36 using namespace std;
  37 using namespace std::chrono;
  38 using namespace std::placeholders;
  39
  40 Q_DECLARE_METATYPE(std::string);
  41 Q_DECLARE_METATYPE(std::vector<std::string>);
  42
  43 MainWindow *global_mainwindow = nullptr;
  44
  45 namespace {
  46
  47 void schedule_cut_signal(int ignored)
  48 {
  49         global_mixer->schedule_cut();
  50 }
  51
  52 void quit_signal(int ignored)
  53 {
  54         global_mainwindow->close();
  55 }
  56
  57 constexpr unsigned DB_NO_FLAGS = 0x0;
  58 constexpr unsigned DB_WITH_SIGN = 0x1;
  59 constexpr unsigned DB_BARE = 0x2;
  60
  61 string format_db(double db, unsigned flags)
  62 {
  63         string text;
  64         if (flags & DB_WITH_SIGN) {
  65                 if (isfinite(db)) {
  66                         char buf[256];
  67                         snprintf(buf, sizeof(buf), "%+.1f", db);
  68                         text = buf;
  69                 } else if (db < 0.0) {
  70                         text = "-∞";
  71                 } else {
  72                         // Should never happen, really.
  73                         text = "+∞";
  74                 }
  75         } else {
  76                 if (isfinite(db)) {
  77                         char buf[256];
  78                         snprintf(buf, sizeof(buf), "%.1f", db);
  79                         text = buf;
  80                 } else if (db < 0.0) {
  81                         text = "-∞";
  82                 } else {
  83                         // Should never happen, really.
  84                         text = "∞";
  85                 }
  86         }
  87         if (!(flags & DB_BARE)) {
  88                 text += " dB";
  89         }
  90         return text;
  91 }
  92
  93 }  // namespace
  94
  95 MainWindow::MainWindow()
  96         : ui(new Ui::MainWindow)
  97 {
  98         global_mainwindow = this;
  99         ui->setupUi(this);
 100
 101         global_disk_space_estimator = new DiskSpaceEstimator(bind(&MainWindow::report_disk_space, this, _1, _2));
 102         disk_free_label = new QLabel(this);
 103         disk_free_label->setStyleSheet("QLabel {padding-right: 5px;}");
 104         ui->menuBar->setCornerWidget(disk_free_label);
 105
 106         ui->me_live->set_output(Mixer::OUTPUT_LIVE);
 107         ui->me_preview->set_output(Mixer::OUTPUT_PREVIEW);
 108
 109         // The menus.
 110         connect(ui->cut_action, &QAction::triggered, this, &MainWindow::cut_triggered);
 111         connect(ui->exit_action, &QAction::triggered, this, &MainWindow::exit_triggered);
 112         connect(ui->about_action, &QAction::triggered, this, &MainWindow::about_triggered);
 113         connect(ui->input_mapping_action, &QAction::triggered, this, &MainWindow::input_mapping_triggered);
 114
 115         if (global_flags.x264_video_to_http) {
 116                 connect(ui->x264_bitrate_action, &QAction::triggered, this, &MainWindow::x264_bitrate_triggered);
 117         } else {
 118                 ui->x264_bitrate_action->setEnabled(false);
 119         }
 120
 121         // Hook up the transition buttons. (Keyboard shortcuts are set in set_transition_names().)
 122         // TODO: Make them dynamic.
 123         connect(ui->transition_btn1, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 0));
 124         connect(ui->transition_btn2, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 1));
 125         connect(ui->transition_btn3, &QPushButton::clicked, bind(&MainWindow::transition_clicked, this, 2));
 126
 127         // Aiee...
 128         transition_btn1 = ui->transition_btn1;
 129         transition_btn2 = ui->transition_btn2;
 130         transition_btn3 = ui->transition_btn3;
 131         qRegisterMetaType<string>("std::string");
 132         qRegisterMetaType<vector<string>>("std::vector<std::string>");
 133         connect(ui->me_live, &GLWidget::transition_names_updated, this, &MainWindow::set_transition_names);
 134         qRegisterMetaType<Mixer::Output>("Mixer::Output");
 135
 136         last_audio_level_callback = steady_clock::now() - seconds(1);
 137 }
 138
 139 void MainWindow::resizeEvent(QResizeEvent* event)
 140 {
 141         QMainWindow::resizeEvent(event);
 142
 143         // Ask for a relayout, but only after the event loop is done doing relayout
 144         // on everything else.
 145         QMetaObject::invokeMethod(this, "relayout", Qt::QueuedConnection);
 146 }
 147
 148 void MainWindow::mixer_created(Mixer *mixer)
 149 {
 150         // Make the previews.
 151         unsigned num_previews = mixer->get_num_channels();
 152
 153         for (unsigned i = 0; i < num_previews; ++i) {
 154                 Mixer::Output output = Mixer::Output(Mixer::OUTPUT_INPUT0 + i);
 155
 156                 QWidget *preview = new QWidget(this);
 157                 Ui::Display *ui_display = new Ui::Display;
 158                 ui_display->setupUi(preview);
 159                 ui_display->label->setText(mixer->get_channel_name(output).c_str());
 160                 ui_display->display->set_output(output);
 161                 ui->preview_displays->insertWidget(previews.size(), preview, 1);
 162                 previews.push_back(ui_display);
 163
 164                 // Hook up the click.
 165                 connect(ui_display->display, &GLWidget::clicked, bind(&MainWindow::channel_clicked, this, i));
 166
 167                 // Let the theme update the text whenever the resolution or color changed.
 168                 connect(ui_display->display, &GLWidget::name_updated, this, &MainWindow::update_channel_name);
 169                 connect(ui_display->display, &GLWidget::color_updated, this, &MainWindow::update_channel_color);
 170
 171                 // Hook up the keyboard key.
 172                 QShortcut *shortcut = new QShortcut(QKeySequence(Qt::Key_1 + i), this);
 173                 connect(shortcut, &QShortcut::activated, bind(&MainWindow::channel_clicked, this, i));
 174
 175                 // Hook up the white balance button (irrelevant if invisible).
 176                 ui_display->wb_button->setVisible(mixer->get_supports_set_wb(output));
 177                 connect(ui_display->wb_button, &QPushButton::clicked, bind(&MainWindow::wb_button_clicked, this, i));
 178         }
 179
 180         // Audio miniview: Make some channels!
 181         for (unsigned i = 0; i < num_previews; ++i) {
 182                 Mixer::Output output = Mixer::Output(Mixer::OUTPUT_INPUT0 + i);
 183
 184                 QWidget *channel = new QWidget(this);
 185                 Ui::AudioMiniView *ui_audio_miniview = new Ui::AudioMiniView;
 186                 ui_audio_miniview->setupUi(channel);
 187                 ui_audio_miniview->channel_desc_label->setFullText(
 188                         QString::fromStdString(mixer->get_channel_name(output)));
 189                 ui->faders->addWidget(channel);
 190
 191                 connect(ui_audio_miniview->fader, &QAbstractSlider::valueChanged,
 192                         bind(&MainWindow::mini_fader_changed, this, ui_audio_miniview, i, _1));
 193         }
 194
 195         // TODO: Fetch all of the values these for completeness,
 196         // not just the enable knobs implied by flags.
 197         ui->locut_enabled->setChecked(global_mixer->get_audio_mixer()->get_locut_enabled());
 198         ui->gainstaging_knob->setValue(global_mixer->get_audio_mixer()->get_gain_staging_db());
 199         ui->gainstaging_auto_checkbox->setChecked(global_mixer->get_audio_mixer()->get_gain_staging_auto());
 200         ui->compressor_enabled->setChecked(global_mixer->get_audio_mixer()->get_compressor_enabled());
 201         ui->limiter_enabled->setChecked(global_mixer->get_audio_mixer()->get_limiter_enabled());
 202         ui->makeup_gain_auto_checkbox->setChecked(global_mixer->get_audio_mixer()->get_final_makeup_gain_auto());
 203
 204         ui->limiter_threshold_db_display->setText(
 205                 QString::fromStdString(format_db(mixer->get_audio_mixer()->get_limiter_threshold_dbfs(), DB_WITH_SIGN)));
 206         ui->compressor_threshold_db_display->setText(
 207                 QString::fromStdString(format_db(mixer->get_audio_mixer()->get_compressor_threshold_dbfs(), DB_WITH_SIGN)));
 208
 209         connect(ui->locut_cutoff_knob, &QDial::valueChanged, this, &MainWindow::cutoff_knob_changed);
 210         cutoff_knob_changed(ui->locut_cutoff_knob->value());
 211         connect(ui->locut_enabled, &QCheckBox::stateChanged, [this](int state){
 212                 global_mixer->get_audio_mixer()->set_locut_enabled(state == Qt::Checked);
 213         });
 214
 215         connect(ui->gainstaging_knob, &QAbstractSlider::valueChanged, this, &MainWindow::gain_staging_knob_changed);
 216         connect(ui->gainstaging_auto_checkbox, &QCheckBox::stateChanged, [this](int state){
 217                 global_mixer->get_audio_mixer()->set_gain_staging_auto(state == Qt::Checked);
 218         });
 219         connect(ui->makeup_gain_knob, &QAbstractSlider::valueChanged, this, &MainWindow::final_makeup_gain_knob_changed);
 220         connect(ui->makeup_gain_auto_checkbox, &QCheckBox::stateChanged, [this](int state){
 221                 global_mixer->get_audio_mixer()->set_final_makeup_gain_auto(state == Qt::Checked);
 222         });
 223
 224         connect(ui->limiter_threshold_knob, &QDial::valueChanged, this, &MainWindow::limiter_threshold_knob_changed);
 225         connect(ui->compressor_threshold_knob, &QDial::valueChanged, this, &MainWindow::compressor_threshold_knob_changed);
 226         connect(ui->limiter_enabled, &QCheckBox::stateChanged, [this](int state){
 227                 global_mixer->get_audio_mixer()->set_limiter_enabled(state == Qt::Checked);
 228         });
 229         connect(ui->compressor_enabled, &QCheckBox::stateChanged, [this](int state){
 230                 global_mixer->get_audio_mixer()->set_compressor_enabled(state == Qt::Checked);
 231         });
 232         connect(ui->reset_meters_button, &QPushButton::clicked, this, &MainWindow::reset_meters_button_clicked);
 233         mixer->set_audio_level_callback(bind(&MainWindow::audio_level_callback, this, _1, _2, _3, _4, _5, _6, _7, _8));
 234
 235         struct sigaction act;
 236         memset(&act, 0, sizeof(act));
 237         act.sa_handler = schedule_cut_signal;
 238         act.sa_flags = SA_RESTART;
 239         sigaction(SIGHUP, &act, nullptr);
 240
 241         // Mostly for debugging. Don't override SIGINT, that's so evil if
 242         // shutdown isn't instant.
 243         memset(&act, 0, sizeof(act));
 244         act.sa_handler = quit_signal;
 245         act.sa_flags = SA_RESTART;
 246         sigaction(SIGUSR1, &act, nullptr);
 247 }
 248
 249 void MainWindow::mixer_shutting_down()
 250 {
 251         ui->me_live->clean_context();
 252         ui->me_preview->clean_context();
 253         for (Ui::Display *display : previews) {
 254                 display->display->clean_context();
 255         }
 256 }
 257
 258 void MainWindow::cut_triggered()
 259 {
 260         global_mixer->schedule_cut();
 261 }
 262
 263 void MainWindow::x264_bitrate_triggered()
 264 {
 265         bool ok;
 266         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);
 267         if (ok && new_bitrate >= 100 && new_bitrate <= 100000) {
 268                 global_flags.x264_bitrate = new_bitrate;
 269                 global_mixer->change_x264_bitrate(new_bitrate);
 270         }
 271 }
 272
 273 void MainWindow::exit_triggered()
 274 {
 275         close();
 276 }
 277
 278 void MainWindow::about_triggered()
 279 {
 280         AboutDialog().exec();
 281 }
 282
 283 void MainWindow::input_mapping_triggered()
 284 {
 285         InputMappingDialog().exec();
 286 }
 287
 288 void MainWindow::gain_staging_knob_changed(int value)
 289 {
 290         ui->gainstaging_auto_checkbox->setCheckState(Qt::Unchecked);
 291
 292         float gain_db = value * 0.1f;
 293         global_mixer->get_audio_mixer()->set_gain_staging_db(gain_db);
 294
 295         // The label will be updated by the audio level callback.
 296 }
 297
 298 void MainWindow::final_makeup_gain_knob_changed(int value)
 299 {
 300         ui->makeup_gain_auto_checkbox->setCheckState(Qt::Unchecked);
 301
 302         float gain_db = value * 0.1f;
 303         global_mixer->get_audio_mixer()->set_final_makeup_gain_db(gain_db);
 304
 305         // The label will be updated by the audio level callback.
 306 }
 307
 308 void MainWindow::cutoff_knob_changed(int value)
 309 {
 310         float octaves = value * 0.1f;
 311         float cutoff_hz = 20.0 * pow(2.0, octaves);
 312         global_mixer->get_audio_mixer()->set_locut_cutoff(cutoff_hz);
 313
 314         char buf[256];
 315         snprintf(buf, sizeof(buf), "%ld Hz", lrintf(cutoff_hz));
 316         ui->locut_cutoff_display->setText(buf);
 317 }
 318
 319 void MainWindow::report_disk_space(off_t free_bytes, double estimated_seconds_left)
 320 {
 321         char time_str[256];
 322         if (estimated_seconds_left < 60.0) {
 323                 strcpy(time_str, "<font color=\"red\">Less than a minute</font>");
 324         } else if (estimated_seconds_left < 1800.0) {  // Less than half an hour: Xm Ys (red).
 325                 int s = lrintf(estimated_seconds_left);
 326                 int m = s / 60;
 327                 s %= 60;
 328                 snprintf(time_str, sizeof(time_str), "<font color=\"red\">%dm %ds</font>", m, s);
 329         } else if (estimated_seconds_left < 3600.0) {  // Less than an hour: Xm.
 330                 int m = lrintf(estimated_seconds_left / 60.0);
 331                 snprintf(time_str, sizeof(time_str), "%dm", m);
 332         } else if (estimated_seconds_left < 36000.0) {  // Less than ten hours: Xh Ym.
 333                 int m = lrintf(estimated_seconds_left / 60.0);
 334                 int h = m / 60;
 335                 m %= 60;
 336                 snprintf(time_str, sizeof(time_str), "%dh %dm", h, m);
 337         } else {  // More than ten hours: Xh.
 338                 int h = lrintf(estimated_seconds_left / 3600.0);
 339                 snprintf(time_str, sizeof(time_str), "%dh", h);
 340         }
 341         char buf[256];
 342         snprintf(buf, sizeof(buf), "Disk free: %'.0f MB (approx. %s)", free_bytes / 1048576.0, time_str);
 343
 344         std::string label = buf;
 345
 346         post_to_main_thread([this, label]{
 347                 disk_free_label->setText(QString::fromStdString(label));
 348                 ui->menuBar->setCornerWidget(disk_free_label);  // Need to set this again for the sizing to get right.
 349         });
 350 }
 351
 352 void MainWindow::limiter_threshold_knob_changed(int value)
 353 {
 354         float threshold_dbfs = value * 0.1f;
 355         global_mixer->get_audio_mixer()->set_limiter_threshold_dbfs(threshold_dbfs);
 356         ui->limiter_threshold_db_display->setText(
 357                 QString::fromStdString(format_db(threshold_dbfs, DB_WITH_SIGN)));
 358 }
 359
 360 void MainWindow::compressor_threshold_knob_changed(int value)
 361 {
 362         float threshold_dbfs = value * 0.1f;
 363         global_mixer->get_audio_mixer()->set_compressor_threshold_dbfs(threshold_dbfs);
 364         ui->compressor_threshold_db_display->setText(
 365                 QString::fromStdString(format_db(threshold_dbfs, DB_WITH_SIGN)));
 366 }
 367
 368 void MainWindow::mini_fader_changed(Ui::AudioMiniView *ui, int channel, int value)
 369 {
 370         float volume_db = value * 0.1f;
 371
 372         char buf[256];
 373         snprintf(buf, sizeof(buf), "%+.1f dB", volume_db);
 374         ui->fader_label->setText(buf);
 375
 376         global_mixer->get_audio_mixer()->set_fader_volume(channel, volume_db);
 377 }
 378
 379 void MainWindow::reset_meters_button_clicked()
 380 {
 381         global_mixer->reset_meters();
 382         ui->peak_display->setText(QString::fromStdString(format_db(-HUGE_VAL, DB_WITH_SIGN | DB_BARE)));
 383         ui->peak_display->setStyleSheet("");
 384 }
 385
 386 void MainWindow::audio_level_callback(float level_lufs, float peak_db, float global_level_lufs,
 387                                       float range_low_lufs, float range_high_lufs,
 388                                       float gain_staging_db, float final_makeup_gain_db,
 389                                       float correlation)
 390 {
 391         steady_clock::time_point now = steady_clock::now();
 392
 393         // The meters are somewhat inefficient to update. Only update them
 394         // every 100 ms or so (we get updates every 5–20 ms).
 395         double last_update_age = duration<double>(now - last_audio_level_callback).count();
 396         if (last_update_age < 0.100) {
 397                 return;
 398         }
 399         last_audio_level_callback = now;
 400
 401         post_to_main_thread([=]() {
 402                 ui->vu_meter->set_level(level_lufs);
 403                 ui->lra_meter->set_levels(global_level_lufs, range_low_lufs, range_high_lufs);
 404                 ui->correlation_meter->set_correlation(correlation);
 405
 406                 ui->peak_display->setText(QString::fromStdString(format_db(peak_db, DB_BARE)));
 407                 if (peak_db > -0.1f) {  // -0.1 dBFS is EBU peak limit.
 408                         ui->peak_display->setStyleSheet("QLabel { background-color: red; color: white; }");
 409                 } else {
 410                         ui->peak_display->setStyleSheet("");
 411                 }
 412
 413                 ui->gainstaging_knob->blockSignals(true);
 414                 ui->gainstaging_knob->setValue(lrintf(gain_staging_db * 10.0f));
 415                 ui->gainstaging_knob->blockSignals(false);
 416                 ui->gainstaging_db_display->setText(
 417                         QString::fromStdString(format_db(gain_staging_db, DB_WITH_SIGN)));
 418
 419                 ui->makeup_gain_knob->blockSignals(true);
 420                 ui->makeup_gain_knob->setValue(lrintf(final_makeup_gain_db * 10.0f));
 421                 ui->makeup_gain_knob->blockSignals(false);
 422                 ui->makeup_gain_db_display->setText(
 423                         QString::fromStdString(format_db(final_makeup_gain_db, DB_WITH_SIGN)));
 424         });
 425 }
 426
 427 void MainWindow::relayout()
 428 {
 429         int height = ui->vertical_layout->geometry().height();
 430
 431         double remaining_height = height;
 432
 433         // Allocate the height; the most important part is to keep the main displays
 434         // at 16:9 if at all possible.
 435         double me_width = ui->me_preview->width();
 436         double me_height = me_width * 9.0 / 16.0 + ui->label_preview->height() + ui->preview_vertical_layout->spacing();
 437
 438         // TODO: Scale the widths when we need to do this.
 439         if (me_height / double(height) > 0.8) {
 440                 me_height = height * 0.8;
 441         }
 442         remaining_height -= me_height + ui->vertical_layout->spacing();
 443
 444         // Space between the M/E displays and the audio strip.
 445         remaining_height -= ui->vertical_layout->spacing();
 446
 447         // The previews will be constrained by the remaining height, and the width.
 448         double preview_label_height = previews[0]->title_bar->geometry().height() +
 449                 previews[0]->main_vertical_layout->spacing();
 450         int preview_total_width = ui->preview_displays->geometry().width() - (previews.size() - 1) * ui->preview_displays->spacing();
 451         double preview_height = min(remaining_height - preview_label_height, (preview_total_width / double(previews.size())) * 9.0 / 16.0);
 452         remaining_height -= preview_height + preview_label_height + ui->vertical_layout->spacing();
 453
 454         ui->vertical_layout->setStretch(0, lrintf(me_height));
 455         ui->vertical_layout->setStretch(1, lrintf(remaining_height));  // Audio strip.
 456         ui->vertical_layout->setStretch(2, lrintf(preview_height + preview_label_height));
 457
 458         // Set the widths for the previews.
 459         double preview_width = preview_height * 16.0 / 9.0;
 460         for (unsigned i = 0; i < previews.size(); ++i) {
 461                 ui->preview_displays->setStretch(i, lrintf(preview_width));
 462         }
 463
 464         // The preview horizontal spacer.
 465         double remaining_preview_width = preview_total_width - previews.size() * preview_width;
 466         ui->preview_displays->setStretch(previews.size(), lrintf(remaining_preview_width));
 467 }
 468
 469 void MainWindow::set_transition_names(vector<string> transition_names)
 470 {
 471         if (transition_names.size() < 1 || transition_names[0].empty()) {
 472                 transition_btn1->setText(QString(""));
 473         } else {
 474                 transition_btn1->setText(QString::fromStdString(transition_names[0] + " (J)"));
 475                 ui->transition_btn1->setShortcut(QKeySequence("J"));
 476         }
 477         if (transition_names.size() < 2 || transition_names[1].empty()) {
 478                 transition_btn2->setText(QString(""));
 479         } else {
 480                 transition_btn2->setText(QString::fromStdString(transition_names[1] + " (K)"));
 481                 ui->transition_btn2->setShortcut(QKeySequence("K"));
 482         }
 483         if (transition_names.size() < 3 || transition_names[2].empty()) {
 484                 transition_btn3->setText(QString(""));
 485         } else {
 486                 transition_btn3->setText(QString::fromStdString(transition_names[2] + " (L)"));
 487                 ui->transition_btn3->setShortcut(QKeySequence("L"));
 488         }
 489 }
 490
 491 void MainWindow::update_channel_name(Mixer::Output output, const string &name)
 492 {
 493         if (output >= Mixer::OUTPUT_INPUT0) {
 494                 unsigned channel = output - Mixer::OUTPUT_INPUT0;
 495                 previews[channel]->label->setText(name.c_str());
 496         }
 497 }
 498
 499 void MainWindow::update_channel_color(Mixer::Output output, const string &color)
 500 {
 501         if (output >= Mixer::OUTPUT_INPUT0) {
 502                 unsigned channel = output - Mixer::OUTPUT_INPUT0;
 503                 previews[channel]->frame->setStyleSheet(QString::fromStdString("background-color:" + color));
 504         }
 505 }
 506
 507 void MainWindow::transition_clicked(int transition_number)
 508 {
 509         global_mixer->transition_clicked(transition_number);
 510 }
 511
 512 void MainWindow::channel_clicked(int channel_number)
 513 {
 514         if (current_wb_pick_display == channel_number) {
 515                 // The picking was already done from eventFilter(), since we don't get
 516                 // the mouse pointer here.
 517         } else {
 518                 global_mixer->channel_clicked(channel_number);
 519         }
 520 }
 521
 522 void MainWindow::wb_button_clicked(int channel_number)
 523 {
 524         current_wb_pick_display = channel_number;
 525         QApplication::setOverrideCursor(Qt::CrossCursor);
 526 }
 527
 528 bool MainWindow::eventFilter(QObject *watched, QEvent *event)
 529 {
 530         if (current_wb_pick_display != -1 &&
 531             event->type() == QEvent::MouseButtonRelease &&
 532             watched->isWidgetType()) {
 533                 QApplication::restoreOverrideCursor();
 534                 if (watched == previews[current_wb_pick_display]->display) {
 535                         const QMouseEvent *mouse_event = (QMouseEvent *)event;
 536                         set_white_balance(current_wb_pick_display, mouse_event->x(), mouse_event->y());
 537                 } else {
 538                         // The user clicked on something else, give up.
 539                         // (The click goes through, which might not be ideal, but, yes.)
 540                         current_wb_pick_display = -1;
 541                 }
 542         }
 543         return false;
 544 }
 545
 546 namespace {
 547
 548 double srgb_to_linear(double x)
 549 {
 550         if (x < 0.04045) {
 551                 return x / 12.92;
 552         } else {
 553                 return pow((x + 0.055) / 1.055, 2.4);
 554         }
 555 }
 556
 557 }  // namespace
 558
 559 void MainWindow::set_white_balance(int channel_number, int x, int y)
 560 {
 561         // Set the white balance to neutral for the grab. It's probably going to
 562         // flicker a bit, but hopefully this display is not live anyway.
 563         global_mixer->set_wb(Mixer::OUTPUT_INPUT0 + channel_number, 0.5, 0.5, 0.5);
 564         previews[channel_number]->display->updateGL();
 565         QRgb reference_color = previews[channel_number]->display->grabFrameBuffer().pixel(x, y);
 566
 567         double r = srgb_to_linear(qRed(reference_color) / 255.0);
 568         double g = srgb_to_linear(qGreen(reference_color) / 255.0);
 569         double b = srgb_to_linear(qBlue(reference_color) / 255.0);
 570         global_mixer->set_wb(Mixer::OUTPUT_INPUT0 + channel_number, r, g, b);
 571         previews[channel_number]->display->updateGL();
 572 }