Method xmlSaveState

pj_plotting/widget/src/PlotWidget.cpp:481–560

}

QDomElement PlotWidget::xmlSaveState(QDomDocument& doc) const {
  QDomElement plot_element = doc.createElement(QStringLiteral("plot"));
  plot_element.setAttribute(QStringLiteral("id"), state_id_);
  plot_element.setAttribute(
      QStringLiteral("mode"), isXYPlot() ? QStringLiteral("XYPlot") : QStringLiteral("TimeSeries"));
  plot_element.setAttribute(QStringLiteral("line_width"), lineWidthToString(lineWidth()));
  // Style and width are plot-level properties (every curve shares them; only
  // colour is per-curve), so they are saved once on the <plot>, not per <curve>.
  plot_element.setAttribute(QStringLiteral("style"), curveStyleToString(curveStyle()));
  plot_element.setAttribute(QStringLiteral("title"), qwtPlot()->title().text());
  plot_element.setAttribute(
      QStringLiteral("tracker_enabled"), tracker_enabled_ ? QStringLiteral("true") : QStringLiteral("false"));

  // Skip the <range> element when the canvas has not yet computed a real
  // viewport (e.g. drop happened immediately before save) -- a degenerate
  // rect would restore as a zero-width window and hide everything. Without
  // <range>, xmlLoadState falls back to zoomOut(), which auto-fits.
  const QRectF rect = currentBoundingRect();
  if (rect.left() != rect.right() && rect.top() != rect.bottom()) {
    QDomElement range_element = doc.createElement(QStringLiteral("range"));
    range_element.setAttribute(QStringLiteral("bottom"), QString::number(rect.bottom(), 'f', 6));
    range_element.setAttribute(QStringLiteral("top"), QString::number(rect.top(), 'f', 6));
    // The X axis of a time-series plot is TIME: persist it in ABSOLUTE seconds,
    // not the display-relative seconds the Qwt axis speaks (display = absolute -
    // offset; see pj_runtime/Time.h). PJ4's display offset is per-dataset and
    // live, so a display-relative range only frames the right instant for the
    // offset present at save time — storing absolute makes the restored range
    // correct regardless of the offset state at load (the "Use time offset"
    // toggle, reloaded data, a layout shared between machines). The time axis is
    // ALWAYS stored absolute — no marker is written; on load the plot MODE
    // (time-series vs XY) is what decides whether to undo the offset. XY plots' X is
    // a value, not time, so they keep their raw axis coordinates.
    if (isXYPlot()) {
      range_element.setAttribute(QStringLiteral("left"), QString::number(rect.left(), 'f', 6));
      range_element.setAttribute(QStringLiteral("right"), QString::number(rect.right(), 'f', 6));
    } else {
      const double offset_sec = displayOffsetSeconds();
      range_element.setAttribute(QStringLiteral("left"), QString::number(rect.left() + offset_sec, 'f', 6));
      range_element.setAttribute(QStringLiteral("right"), QString::number(rect.right() + offset_sec, 'f', 6));
    }
    plot_element.appendChild(range_element);
  }

  // A curve is identified by its stable topic+field path (PJ::LayoutXml), not
  // the engine's opaque per-load catalog key. On load — layout file or undo/redo
  // snapshot alike — the path is re-resolved against the current dataset(s) to
  // the concrete key (PJ::LayoutXml::rebindCurveKeys), so the saved form stays
  // valid across reloads and similar datasets.
  const auto write_stable_path = [&](QDomElement& element, const QString& topic_attr, const QString& field_attr,
                                     const QString& key) {
    if (catalog_ == nullptr) {
      return;
    }
    if (const auto descriptor = catalog_->curveDescriptor(key); descriptor.has_value()) {
      element.setAttribute(topic_attr, descriptor->topic_name);
      element.setAttribute(field_attr, descriptor->field_path);
    }
  };