fix transparency in qgsmaprenderer

Author: Gustry

src/core/qgsmaprendererjob.cpp

@@ -350,7 +350,7 @@ void QgsMapRendererJob::cleanupJobs( LayerRenderJobs& jobs )
 QImage QgsMapRendererJob::composeImage( const QgsMapSettings& settings, const LayerRenderJobs& jobs )
 {
   QImage image( settings.outputSize(), settings.outputImageFormat() );
-  image.fill( settings.backgroundColor().rgb() );
+  image.fill( settings.backgroundColor().rgba() );
 
   QPainter painter( &image );
 

src/core/qgsmaprenderersequentialjob.cpp

@@ -31,6 +31,7 @@ QgsMapRendererSequentialJob::QgsMapRendererSequentialJob( const QgsMapSettings&
   mImage = QImage( mSettings.outputSize(), mSettings.outputImageFormat() );
   mImage.setDotsPerMeterX( 1000 * settings.outputDpi() / 25.4 );
   mImage.setDotsPerMeterY( 1000 * settings.outputDpi() / 25.4 );
+  mImage.fill( settings.backgroundColor().rgba() );
 }
 
 QgsMapRendererSequentialJob::~QgsMapRendererSequentialJob()