Method buildTimelineAlignRail

pj_app/src/MainWindow.cpp:4308–4388

}

void MainWindow::buildTimelineAlignRail() {
  // A 24-px icon column on the right edge of the timeline panel that visually
  // continues the global toolbar above it (they line up when the right panel is
  // closed). Holds the Source Timeline alignment actions. The buttons mirror the
  // global toolbar's style (theme-tinted SVG, chrome-metrics sizing); the rail's
  // show/hide tracks the strip in applyBottomPanelConstraints.
  auto* outer = qobject_cast<QVBoxLayout*>(ui_->timelineAlignRail->layout());
  if (outer == nullptr) {
    return;
  }
  outer->setSpacing(0);
  outer->setContentsMargins(0, 0, 0, 0);

  auto add_button = [this, outer](const char* object_name, const char* icon_path, const char* tooltip) -> QToolButton* {
    auto* btn = new SvgButton(ui_->timelineAlignRail);
    btn->setObjectName(QString::fromLatin1(object_name));
    btn->setIconPath(QString::fromLatin1(icon_path));
    btn->setExtent(chrome_metrics_.icon_size + chrome_metrics_.icon_padding, chrome_metrics_.icon_size);
    btn->setToolTip(tr(tooltip));
    outer->addWidget(btn);
    return btn;
  };

  QToolButton* align_left = add_button(
      "buttonAlignStarts", ":/resources/svg/align_horizontal_left.svg",
      "Align sources: line every source's start up at the earliest start");

  QToolButton* align_right = add_button(
      "buttonAlignEnds", ":/resources/svg/align_horizontal_right.svg",
      "Align sources: line every source's end up at the latest end");

  // Zoom-out-horizontally: fit all source bars into the view (the timeline's
  // equivalent of the plot's "Zoom Out Horizontally", same icon). Replaces the
  // former align-centers action on the rail.
  QToolButton* zoom_fit =
      add_button("buttonTimelineFit", ":/resources/svg/zoom_horizontal.svg", "Zoom out to fit all sources");

  // "Snap to" toggle — when on, a dragged bar's start/end snaps to a neighbour's
  // edge (with a guide line). Checkable; on by default.
  QToolButton* snap_toggle = add_button(
      "buttonTimelineSnap", ":/resources/svg/transition_push.svg", "Snap to neighbouring dataset edges while dragging");
  snap_toggle->setCheckable(true);
  snap_toggle->setChecked(true);

  // Stretch pins the align/snap icons to the top of the content area; the reset
  // button below it sits at the BOTTOM of the rail.
  outer->addStretch(1);
  QToolButton* reset_all =
      add_button("buttonTimelineReset", ":/resources/svg/restart_alt.svg", "Reset all timeline changes");

  if (source_timeline_controller_ != nullptr) {
    connect(align_left, &QToolButton::clicked, source_timeline_controller_, &SourceTimelineController::alignStarts);
    connect(align_right, &QToolButton::clicked, source_timeline_controller_, &SourceTimelineController::alignEnds);
    connect(reset_all, &QToolButton::clicked, source_timeline_controller_, &SourceTimelineController::resetAll);
  }
  if (source_timeline_ != nullptr) {
    connect(zoom_fit, &QToolButton::clicked, source_timeline_, &Timeline::zoomToFit);
    connect(snap_toggle, &QToolButton::toggled, source_timeline_, &Timeline::setSnapEnabled);