Method rescale

pj_plotting/widget/src/PlotMagnifier.cpp:29–102

}

void PlotMagnifier::rescale(double factor, AxisMode axis) {
  factor = qAbs(1.0 / factor);

  QwtPlot* qwt_plot = plot();
  if (qwt_plot == nullptr || factor == 1.0) {
    return;
  }

  bool do_replot = false;
  const bool auto_replot = qwt_plot->autoReplot();
  qwt_plot->setAutoReplot(false);

  const int axis_list[2] = {QwtPlot::xBottom, QwtPlot::yLeft};
  QRectF new_rect;

  for (int index = 0; index < 2; ++index) {
    double temp_factor = factor;
    if (index == 1 && axis == kXAxis) {
      temp_factor = 1.0;
    }
    if (index == 0 && axis == kYAxis) {
      temp_factor = 1.0;
    }

    const int axis_id = axis_list[index];
    if (!isAxisEnabled(axis_id)) {
      continue;
    }

    const QwtScaleMap scale_map = qwt_plot->canvasMap(axis_id);
    double v1 = scale_map.s1();
    double v2 = scale_map.s2();
    double center = axis_id == QwtPlot::yLeft ? mouse_position_.y() : mouse_position_.x();

    if (scale_map.transformation()) {
      v1 = scale_map.transform(v1);
      v2 = scale_map.transform(v2);
    }

    const double width = v2 - v1;
    const double ratio = (v2 - center) / width;
    v1 = center - width * temp_factor * (1 - ratio);
    v2 = center + width * temp_factor * ratio;

    bool reversed_axis = false;
    if (v1 > v2) {
      reversed_axis = true;
      std::swap(v1, v2);
    }

    if (scale_map.transformation()) {
      v1 = scale_map.invTransform(v1);
      v2 = scale_map.invTransform(v2);
    }

    v1 = std::max(v1, lower_bounds_[axis_id]);
    v2 = std::min(v2, upper_bounds_[axis_id]);
    qwt_plot->setAxisScale(axis_id, reversed_axis ? v2 : v1, reversed_axis ? v1 : v2);