void QgsCentroidFillSymbolLayerV2::startRender( QgsSymbolV2RenderContext& context )
{
  mMarker->setAlpha( context.alpha() );
  mMarker->setOutputUnit( context.outputUnit() );

  mMarker->startRender( context.renderContext() );
}
void QgsMarkerLineSymbolLayerV2::startRender( QgsSymbolV2RenderContext& context )
{
  mMarker->setAlpha( context.alpha() );
  mMarker->setOutputUnit( context.outputUnit() );

  // if being rotated, it gets initialized with every line segment
  int hints = 0;
  if ( mRotateMarker )
    hints |= QgsSymbolV2::DataDefinedRotation;
  if ( context.renderHints() & QgsSymbolV2::DataDefinedSizeScale )
    hints |= QgsSymbolV2::DataDefinedSizeScale;
  mMarker->setRenderHints( hints );

  mMarker->startRender( context.renderContext() );
}
void QgsPointPatternFillSymbolLayer::startRender( QgsSymbolV2RenderContext& context )
{
  //render 3 rows and columns in one go to easily incorporate displacement
  double width = context.outputPixelSize( mDistanceX ) * 2.0;
  double height = context.outputPixelSize( mDistanceY ) * 2.0;

  QImage patternImage( width, height, QImage::Format_ARGB32 );
  patternImage.fill( 0 );

  if ( mMarkerSymbol )
  {
    QPainter p( &patternImage );

    //marker rendering needs context for drawing on patternImage
    QgsRenderContext pointRenderContext;
    pointRenderContext.setPainter( &p );
    pointRenderContext.setRasterScaleFactor( 1.0 );
    pointRenderContext.setScaleFactor( context.renderContext().scaleFactor() * context.renderContext().rasterScaleFactor() );
    QgsMapToPixel mtp( context.renderContext().mapToPixel().mapUnitsPerPixel() / context.renderContext().rasterScaleFactor() );
    pointRenderContext.setMapToPixel( mtp );
    pointRenderContext.setForceVectorOutput( false );

    mMarkerSymbol->setOutputUnit( context.outputUnit() );
    mMarkerSymbol->startRender( pointRenderContext );

    //render corner points
    mMarkerSymbol->renderPoint( QPointF( 0, 0 ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( width, 0 ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( 0, height ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( width, height ), context.feature(), pointRenderContext );

    //render displaced points
    double displacementPixelX = context.outputPixelSize( mDisplacementX );
    double displacementPixelY = context.outputPixelSize( mDisplacementY );
    mMarkerSymbol->renderPoint( QPointF( width / 2.0, -displacementPixelY ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( displacementPixelX, height / 2.0 ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( width / 2.0 + displacementPixelX, height / 2.0 - displacementPixelY ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( width + displacementPixelX, height / 2.0 ), context.feature(), pointRenderContext );
    mMarkerSymbol->renderPoint( QPointF( width / 2.0, height - displacementPixelY ), context.feature(), pointRenderContext );

    mMarkerSymbol->stopRender( pointRenderContext );
  }

  if ( !doubleNear( context.alpha(), 1.0 ) )
  {
    QImage transparentImage = patternImage.copy();
    QgsSymbolLayerV2Utils::multiplyImageOpacity( &transparentImage, context.alpha() );
    mBrush.setTextureImage( transparentImage );
  }
  else
  {
    mBrush.setTextureImage( patternImage );
  }
  QTransform brushTransform;
  brushTransform.scale( 1.0 / context.renderContext().rasterScaleFactor(), 1.0 / context.renderContext().rasterScaleFactor() );
  mBrush.setTransform( brushTransform );

  if ( mOutline )
  {
    mOutline->startRender( context.renderContext() );
  }
}