void QgsVectorLayerDiagramProvider::drawLabel( QgsRenderContext &context, pal::LabelPosition *label ) const
{
#if 1 // XXX strk
  // features are pre-rotated but not scaled/translated,
  // so we only disable rotation here. Ideally, they'd be
  // also pre-scaled/translated, as suggested here:
  // https://issues.qgis.org/issues/11856
  QgsMapToPixel xform = context.mapToPixel();
  xform.setMapRotation( 0, 0, 0 );
#else
  const QgsMapToPixel &xform = context.mapToPixel();
#endif

  QgsDiagramLabelFeature *dlf = dynamic_cast<QgsDiagramLabelFeature *>( label->getFeaturePart()->feature() );

  QgsFeature feature;
  feature.setFields( mFields );
  feature.setValid( true );
  feature.setId( label->getFeaturePart()->featureId() );
  feature.setAttributes( dlf->attributes() );

  context.expressionContext().setFeature( feature );

  //calculate top-left point for diagram
  //first, calculate the centroid of the label (accounts for PAL creating
  //rotated labels when we do not want to draw the diagrams rotated)
  double centerX = 0;
  double centerY = 0;
  for ( int i = 0; i < 4; ++i )
  {
    centerX += label->getX( i );
    centerY += label->getY( i );
  }
  QgsPointXY outPt( centerX / 4.0, centerY / 4.0 );
  //then, calculate the top left point for the diagram with this center position
  QgsPointXY centerPt = xform.transform( outPt.x() - label->getWidth() / 2,
                                         outPt.y() - label->getHeight() / 2 );

  mSettings.renderer()->renderDiagram( feature, context, centerPt.toQPointF(), mSettings.dataDefinedProperties() );

  //insert into label search tree to manipulate position interactively
  mEngine->results()->mLabelSearchTree->insertLabel( label, label->getFeaturePart()->featureId(), mLayerId, QString(), QFont(), true, false );

}
QgsRasterLayerRenderer::QgsRasterLayerRenderer( QgsRasterLayer* layer, QgsRenderContext& rendererContext )
    : QgsMapLayerRenderer( layer->id() )
    , mRasterViewPort( nullptr )
    , mPipe( nullptr )
{

  mPainter = rendererContext.painter();
  const QgsMapToPixel& theQgsMapToPixel = rendererContext.mapToPixel();
  mMapToPixel = &theQgsMapToPixel;

  QgsMapToPixel mapToPixel = theQgsMapToPixel;
  if ( mapToPixel.mapRotation() )
  {
    // unset rotation for the sake of local computations.
    // Rotation will be handled by QPainter later
    // TODO: provide a method of QgsMapToPixel to fetch map center
    //       in geographical units
    QgsPoint center = mapToPixel.toMapCoordinates(
                        mapToPixel.mapWidth() / 2.0,
                        mapToPixel.mapHeight() / 2.0
                      );
    mapToPixel.setMapRotation( 0, center.x(), center.y() );
  }

  QgsRectangle myProjectedViewExtent;
  QgsRectangle myProjectedLayerExtent;

  if ( rendererContext.coordinateTransform() )
  {
    QgsDebugMsg( "coordinateTransform set -> project extents." );
    try
    {
      myProjectedViewExtent = rendererContext.coordinateTransform()->transformBoundingBox( rendererContext.extent() );
    }
    catch ( QgsCsException &cs )
    {
      QgsMessageLog::logMessage( QObject::tr( "Could not reproject view extent: %1" ).arg( cs.what() ), QObject::tr( "Raster" ) );
      myProjectedViewExtent.setMinimal();
    }

    try
    {
      myProjectedLayerExtent = rendererContext.coordinateTransform()->transformBoundingBox( layer->extent() );
    }
    catch ( QgsCsException &cs )
    {
      QgsMessageLog::logMessage( QObject::tr( "Could not reproject layer extent: %1" ).arg( cs.what() ), QObject::tr( "Raster" ) );
      myProjectedLayerExtent.setMinimal();
    }
  }
  else
  {
    QgsDebugMsg( "coordinateTransform not set" );
    myProjectedViewExtent = rendererContext.extent();
    myProjectedLayerExtent = layer->extent();
  }

  // clip raster extent to view extent
  QgsRectangle myRasterExtent = myProjectedViewExtent.intersect( &myProjectedLayerExtent );
  if ( myRasterExtent.isEmpty() )
  {
    QgsDebugMsg( "draw request outside view extent." );
    // nothing to do
    return;
  }

  QgsDebugMsg( "theViewExtent is " + rendererContext.extent().toString() );
  QgsDebugMsg( "myProjectedViewExtent is " + myProjectedViewExtent.toString() );
  QgsDebugMsg( "myProjectedLayerExtent is " + myProjectedLayerExtent.toString() );
  QgsDebugMsg( "myRasterExtent is " + myRasterExtent.toString() );

  //
  // The first thing we do is set up the QgsRasterViewPort. This struct stores all the settings
  // relating to the size (in pixels and coordinate system units) of the raster part that is
  // in view in the map window. It also stores the origin.
  //
  //this is not a class level member because every time the user pans or zooms
  //the contents of the rasterViewPort will change
  mRasterViewPort = new QgsRasterViewPort();

  mRasterViewPort->mDrawnExtent = myRasterExtent;
  if ( rendererContext.coordinateTransform() )
  {
    mRasterViewPort->mSrcCRS = layer->crs();
    mRasterViewPort->mDestCRS = rendererContext.coordinateTransform()->destCRS();
    mRasterViewPort->mSrcDatumTransform = rendererContext.coordinateTransform()->sourceDatumTransform();
    mRasterViewPort->mDestDatumTransform = rendererContext.coordinateTransform()->destinationDatumTransform();
  }
  else
  {
    mRasterViewPort->mSrcCRS = QgsCoordinateReferenceSystem(); // will be invalid
    mRasterViewPort->mDestCRS = QgsCoordinateReferenceSystem(); // will be invalid
    mRasterViewPort->mSrcDatumTransform = -1;
    mRasterViewPort->mDestDatumTransform = -1;
  }

  // get dimensions of clipped raster image in device coordinate space (this is the size of the viewport)
  mRasterViewPort->mTopLeftPoint = mapToPixel.transform( myRasterExtent.xMinimum(), myRasterExtent.yMaximum() );
  mRasterViewPort->mBottomRightPoint = mapToPixel.transform( myRasterExtent.xMaximum(), myRasterExtent.yMinimum() );

  // align to output device grid, i.e. floor/ceil to integers
  // TODO: this should only be done if paint device is raster - screen, image
  // for other devices (pdf) it can have floating point origin
  // we could use floating point for raster devices as well, but respecting the
  // output device grid should make it more effective as the resampling is done in
  // the provider anyway
  mRasterViewPort->mTopLeftPoint.setX( floor( mRasterViewPort->mTopLeftPoint.x() ) );
  mRasterViewPort->mTopLeftPoint.setY( floor( mRasterViewPort->mTopLeftPoint.y() ) );
  mRasterViewPort->mBottomRightPoint.setX( ceil( mRasterViewPort->mBottomRightPoint.x() ) );
  mRasterViewPort->mBottomRightPoint.setY( ceil( mRasterViewPort->mBottomRightPoint.y() ) );
  // recalc myRasterExtent to aligned values
  myRasterExtent.set(
    mapToPixel.toMapCoordinatesF( mRasterViewPort->mTopLeftPoint.x(),
                                  mRasterViewPort->mBottomRightPoint.y() ),
    mapToPixel.toMapCoordinatesF( mRasterViewPort->mBottomRightPoint.x(),
                                  mRasterViewPort->mTopLeftPoint.y() )
  );

  //raster viewport top left / bottom right are already rounded to int
  mRasterViewPort->mWidth = static_cast<int>( mRasterViewPort->mBottomRightPoint.x() - mRasterViewPort->mTopLeftPoint.x() );
  mRasterViewPort->mHeight = static_cast<int>( mRasterViewPort->mBottomRightPoint.y() - mRasterViewPort->mTopLeftPoint.y() );

  //the drawable area can start to get very very large when you get down displaying 2x2 or smaller, this is becasue
  //mapToPixel.mapUnitsPerPixel() is less then 1,
  //so we will just get the pixel data and then render these special cases differently in paintImageToCanvas()

  QgsDebugMsgLevel( QString( "mapUnitsPerPixel = %1" ).arg( mapToPixel.mapUnitsPerPixel() ), 3 );
  QgsDebugMsgLevel( QString( "mWidth = %1" ).arg( layer->width() ), 3 );
  QgsDebugMsgLevel( QString( "mHeight = %1" ).arg( layer->height() ), 3 );
  QgsDebugMsgLevel( QString( "myRasterExtent.xMinimum() = %1" ).arg( myRasterExtent.xMinimum() ), 3 );
  QgsDebugMsgLevel( QString( "myRasterExtent.xMaximum() = %1" ).arg( myRasterExtent.xMaximum() ), 3 );
  QgsDebugMsgLevel( QString( "myRasterExtent.yMinimum() = %1" ).arg( myRasterExtent.yMinimum() ), 3 );
  QgsDebugMsgLevel( QString( "myRasterExtent.yMaximum() = %1" ).arg( myRasterExtent.yMaximum() ), 3 );

  QgsDebugMsgLevel( QString( "mTopLeftPoint.x() = %1" ).arg( mRasterViewPort->mTopLeftPoint.x() ), 3 );
  QgsDebugMsgLevel( QString( "mBottomRightPoint.x() = %1" ).arg( mRasterViewPort->mBottomRightPoint.x() ), 3 );
  QgsDebugMsgLevel( QString( "mTopLeftPoint.y() = %1" ).arg( mRasterViewPort->mTopLeftPoint.y() ), 3 );
  QgsDebugMsgLevel( QString( "mBottomRightPoint.y() = %1" ).arg( mRasterViewPort->mBottomRightPoint.y() ), 3 );

  QgsDebugMsgLevel( QString( "mWidth = %1" ).arg( mRasterViewPort->mWidth ), 3 );
  QgsDebugMsgLevel( QString( "mHeight = %1" ).arg( mRasterViewPort->mHeight ), 3 );

  // /\/\/\ - added to handle zoomed-in rasters

  // TODO R->mLastViewPort = *mRasterViewPort;

  // TODO: is it necessary? Probably WMS only?
  layer->dataProvider()->setDpi( rendererContext.rasterScaleFactor() * 25.4 * rendererContext.scaleFactor() );


  // copy the whole raster pipe!
  mPipe = new QgsRasterPipe( *layer->pipe() );
}