plotpanner.cpp

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#include "qwt_plot.h"
#include "qwt_scale_map.h"
#include "qwt_scale_div.h"
 
#include "plotpanner.h"
 
void PlotPanner::moveCanvas(int dx, int dy)
{
  if (dx == 0 && dy == 0)
    return;
 
  QwtPlot* plot = this->plot();
  if (plot == NULL)
    return;
 
  const bool doAutoReplot = plot->autoReplot();
  plot->setAutoReplot(false);
 
  QRectF new_rect;
 
  for (int axisPos = 0; axisPos < QwtAxis::AxisPositions; axisPos++)
  {
    const QwtAxisId axisId(axisPos);
 
    if (!isAxisEnabled(axisId))
      continue;
 
    const QwtScaleMap map = plot->canvasMap(axisId);
 
    const double p1 = map.transform(plot->axisScaleDiv(axisId).lowerBound());
    const double p2 = map.transform(plot->axisScaleDiv(axisId).upperBound());
 
    double d1, d2;
    if (QwtAxis::isXAxis(axisPos))
    {
      d1 = map.invTransform(p1 - dx);
      d2 = map.invTransform(p2 - dx);
    }
    else
    {
      d1 = map.invTransform(p1 - dy);
      d2 = map.invTransform(p2 - dy);
    }
 
    plot->setAxisScale(axisId, d1, d2);
 
    if (axisId == QwtPlot::yLeft)
    {
      new_rect.setBottom(d1);
      new_rect.setTop(d2);
    }
    if (axisId == QwtPlot::xBottom)
    {
      new_rect.setLeft(d1);
      new_rect.setRight(d2);
    }
  }
 
  emit rescaled(new_rect);
 
  plot->setAutoReplot(doAutoReplot);
  plot->replot();
}