[Server] Reactivate the capability to print selection with Server 3.4

The capability to print selection has been removed by the commit aaa7003 to
prevent accidental selections showing in exports from composer.

It is reactivated only for QGIS Server.

Fixes #13459 QGIS Server WMS GetPrint request don't respect SELECTION parameter

It's a forward porting of #7185

Author: rldhont

python/core/auto_generated/layout/qgslayoutrendercontext.sip.in

@@ -29,6 +29,7 @@ Stores information relating to the current rendering settings for a layout.
       FlagUseAdvancedEffects,
       FlagForceVectorOutput,
       FlagHideCoverageLayer,
+      FlagDrawSelection,
     };
     typedef QFlags<QgsLayoutRenderContext::Flag> Flags;
 

src/core/layout/qgslayoutitemmap.cpp

@@ -1104,7 +1104,7 @@ QgsMapSettings QgsLayoutItemMap::mapSettings( const QgsRectangle &extent, QSizeF
   jobMapSettings.setFlag( QgsMapSettings::ForceVectorOutput, true ); // force vector output (no caching of marker images etc.)
   jobMapSettings.setFlag( QgsMapSettings::Antialiasing, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagAntialiasing );
   jobMapSettings.setFlag( QgsMapSettings::DrawEditingInfo, false );
-  jobMapSettings.setFlag( QgsMapSettings::DrawSelection, false );
+  jobMapSettings.setFlag( QgsMapSettings::DrawSelection, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagDrawSelection );
   jobMapSettings.setFlag( QgsMapSettings::UseAdvancedEffects, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagUseAdvancedEffects );
   jobMapSettings.setTransformContext( mLayout->project()->transformContext() );
   jobMapSettings.setPathResolver( mLayout->project()->pathResolver() );

src/core/layout/qgslayoutrendercontext.h

@@ -45,6 +45,7 @@ class CORE_EXPORT QgsLayoutRenderContext : public QObject
       FlagUseAdvancedEffects = 1 << 4, //!< Enable advanced effects such as blend modes.
       FlagForceVectorOutput = 1 << 5, //!< Force output in vector format where possible, even if items require rasterization to keep their correct appearance.
       FlagHideCoverageLayer = 1 << 6, //!< Hide coverage layer in outputs
+      FlagDrawSelection = 1 << 7, //!< Draw selection
     };
     Q_DECLARE_FLAGS( Flags, Flag )
 

src/server/services/wms/qgswmsrenderer.cpp

@@ -66,7 +66,6 @@
 #include "qgslayerrestorer.h"
 #include "qgsdxfexport.h"
 #include "qgssymbollayerutils.h"
-#include "qgslayoutitemlegend.h"
 #include "qgsserverexception.h"
 
 #include <QImage>
@@ -80,6 +79,7 @@
 #include "qgslayoutmanager.h"
 #include "qgslayoutexporter.h"
 #include "qgslayoutsize.h"
+#include "qgslayoutrendercontext.h"
 #include "qgslayoutmeasurement.h"
 #include "qgsprintlayout.h"
 #include "qgslayoutpagecollection.h"
@@ -450,7 +450,7 @@ namespace QgsWms
 
   bool QgsRenderer::configurePrintLayout( QgsPrintLayout *c, const QgsMapSettings &mapSettings )
   {
-
+    c->renderContext().setFlag( QgsLayoutRenderContext::FlagDrawSelection, true );
     // Maps are configured first
     QList<QgsLayoutItemMap *> maps;
     c->layoutItems<QgsLayoutItemMap>( maps );