Method refreshPreview

pj_plotting/widget/src/FilterEditorPanel.cpp:566–696

}

void FilterEditorPanel::refreshPreview() {
  if (!preview_plot_ || session_ == nullptr) {
    return;
  }

  // Sources to preview = every selected curve (in list order), or the first
  // available if nothing is selected. Each gets its own ghost + filtered pair, so a
  // multi-select edit previews EVERY series Apply will touch — not just the first.
  std::vector<int> indices;
  const QList<QListWidgetItem*> selected = ui_->series_list->selectedItems();
  if (!selected.isEmpty()) {
    indices.reserve(static_cast<std::size_t>(selected.size()));
    for (const QListWidgetItem* item : selected) {
      indices.push_back(item->data(Qt::UserRole).toInt());
    }
    std::sort(indices.begin(), indices.end());  // list order, not selection-click order
  } else if (!sources_.empty()) {
    indices.push_back(0);
  }

  // Resolve each to its EFFECTIVE input (a filter-output source previews its ORIGINAL
  // input, so re-editing reads as "input -> re-filtered output") and the SELECTED
  // curve's plot colour. De-duplicate by input so two outputs of the same input
  // collapse to one ghost.
  std::vector<PreviewSeries> wanted;
  QString set_key;
  for (const int idx : indices) {
    if (idx < 0 || static_cast<std::size_t>(idx) >= sources_.size()) {
      continue;
    }
    const CurveDescriptor& source = sources_[static_cast<std::size_t>(idx)];
    const CurveDescriptor input = originalInputOf(source);
    if (std::any_of(wanted.begin(), wanted.end(), [&](const PreviewSeries& s) { return s.input.name == input.name; })) {
      continue;
    }
    wanted.push_back(PreviewSeries{.input = input, .source_key = source.name, .color = colorForSource(source)});
    set_key += input.name;
    set_key += QChar('\n');
  }
  if (wanted.empty()) {
    return;
  }

  // Rebuild curves only when the SET of ghosts changes, so tuning a parameter keeps
  // the user's current zoom on the preview.
  const bool rebuilt = (set_key != preview_set_key_);
  if (rebuilt) {
    preview_plot_->removeAllCurves();
    preview_set_key_ = set_key;
    for (PreviewSeries& entry : wanted) {
      // Ghost = the datastore-backed source. Its dash/fade styling is set below.
      if (auto* ghost = preview_plot_->addCurve(entry.input.name, entry.color); ghost != nullptr) {
        entry.ghost = ghost->curve;
      }
      // Filtered = a lazy datastore-backed curve that runs THIS source's filter
      // over the input column on read. It reports the input topic as its source,
      // so PlotWidget's samplesIngested handler refreshes it on the SAME signal as
      // the ghost — the filtered "after" tracks streaming with no timer/extra