C++ (Cpp) QgsMapRenderer::outputDpi Examples

Example #1

File: qgsmapcanvasitem.cpp Project: Adam-Brown/Quantum-GIS

bool QgsMapCanvasItem::setRenderContextVariables( QPainter* p, QgsRenderContext& context ) const
{
  if ( !mMapCanvas || !p )
  {
    return false;
  }
  QgsMapRenderer* mapRenderer = mMapCanvas->mapRenderer();
  if ( !mapRenderer )
  {
    return false;
  }

  context.setPainter( p );
  context.setRendererScale( mMapCanvas->scale() );

  int dpi = mapRenderer->outputDpi();
  int painterDpi = p->device()->logicalDpiX();
  double scaleFactor = 1.0;
  double rasterScaleFactor = 1.0;

  //little trick to find out if painting origines from composer or main map canvas
  if ( data( 1 ).toString() == "composer" )
  {
    rasterScaleFactor = painterDpi / 25.4;
    scaleFactor = dpi / 25.4;
  }
  else
  {
    if ( mapRenderer->outputUnits() == QgsMapRenderer::Millimeters )
    {
      scaleFactor = dpi / 25.4;
    }
  }
  context.setScaleFactor( scaleFactor );
  context.setRasterScaleFactor( rasterScaleFactor );
  return true;
}