backported dxf fixes:

* fix crash when not enabled layers are exported
* fix handing of areas with holes when exporting SVGs
* fix block, hatch and polyline ownership
* fix support for data-defined properties in SVG export
* remove drawRects and let it fallback to drawPath and drawPolygon
* close arcs
* replace writeSolid with writePolygon

(backported b4fc413, 2798ab0, b3c2bd7 and 7031cfb)

python/core/dxf/qgsdxfexport.sip

@@ -63,31 +63,45 @@ class QgsDxfExport
     void writeGroup( int code, const QgsPoint &p, double z = 0.0, bool skipz = false ) /PyName=writeGroupPoint/;
     void writeGroup( QColor color, int exactMatch = 62, int rgbCode = 420, int transparencyCode = 440 );
 
+    //! Write handle
     int writeHandle( int code = 5, int handle = 0 );
 
-    //draw dxf primitives
+    //! Draw dxf primitives
     void writePolyline( const QgsPolyline &line, const QString &layer, const QString &lineStyleName, QColor color,
-                        double width = -1, bool polygon = false );
+                        double width = -1, bool unusedPolygonFlag = false );
 
+    //! Draw dxf polygon (HATCH)
     void writePolygon( const QgsPolygon &polygon, const QString &layer, const QString &hatchPattern, QColor color );
 
+    //! Draw solid
     void writeSolid( const QString &layer, QColor color, const QgsPoint &pt1, const QgsPoint &pt2, const QgsPoint &pt3, const QgsPoint &pt4 );
 
-    //write line (as a polyline)
+    //! Write line (as a polyline)
     void writeLine( const QgsPoint &pt1, const QgsPoint &pt2, const QString &layer, const QString &lineStyleName, QColor color, double width = -1 );
 
+    //! Write point
     void writePoint( const QString &layer, QColor color, const QgsPoint &pt );
 
+    //! Write filled circle (as hatch)
     void writeFilledCircle( const QString &layer, QColor color, const QgsPoint &pt, double radius );
 
+    //! Write circle (as polyline)
     void writeCircle( const QString &layer, QColor color, const QgsPoint &pt, double radius, const QString &lineStyleName, double width );
 
+    //! Write text (TEXT)
     void writeText( const QString &layer, const QString &text, const QgsPoint &pt, double size, double angle, QColor color );
 
+    //! Write mtext (MTEXT)
     void writeMText( const QString &layer, const QString &text, const QgsPoint &pt, double width, double angle, QColor color );
 
     static double mapUnitScaleFactor( double scaleDenominator, QgsSymbolV2::OutputUnit symbolUnits, QGis::UnitType mapUnits );
 
+    //! Return cleaned layer name for use in DXF
     static QString dxfLayerName( const QString &name );
 
+    //! return DXF encoding for Qt encoding
+    static QString dxfEncoding( const QString &name );
+
+    //! return list of available DXF encodings
+    static QStringList encodings();
 };

python/core/symbology-ng/qgssvgcache.sip

@@ -87,6 +87,10 @@ class QgsSvgCache : QObject
     /**Get image data*/
     QByteArray getImageData( const QString &path ) const;
 
+    /**Get SVG content*/
+    const QByteArray& svgContent( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
+                                  double widthScaleFactor, double rasterScaleFactor );
+
   signals:
     /** Emit a signal to be caught by qgisapp and display a msg on status bar */
     void statusChanged( const QString&  theStatusQString );

src/app/qgsdxfexportdialog.cpp

@@ -25,7 +25,7 @@
 #include "qgis.h"
 #include "qgsfieldcombobox.h"
 #include "qgisapp.h"
-#include "qgsmapcanvas.h"
+#include "qgslayertreemapcanvasbridge.h"
 #include "qgsvisibilitypresets.h"
 
 #include <QFileDialog>
@@ -254,7 +254,7 @@ bool QgsVectorLayerAndAttributeModel::setData( const QModelIndex &index, const Q
 QList< QPair<QgsVectorLayer *, int> > QgsVectorLayerAndAttributeModel::layers() const
 {
   QList< QPair<QgsVectorLayer *, int> > layers;
-  QHash< QgsMapLayer *, int > layerIdx;
+  QHash< QString, int > layerIdx;
 
   foreach ( const QModelIndex &idx, mCheckedLeafs )
   {
@@ -265,9 +265,9 @@ QList< QPair<QgsVectorLayer *, int> > QgsVectorLayerAndAttributeModel::layers()
       {
         QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( treeLayer->layer() );
         Q_ASSERT( vl );
-        if ( !layerIdx.contains( vl ) )
+        if ( !layerIdx.contains( vl->id() ) )
         {
-          layerIdx.insert( vl, layers.size() );
+          layerIdx.insert( vl->id(), layers.size() );
           layers << qMakePair<QgsVectorLayer *, int>( vl, mAttributeIdx.value( vl, -1 ) );
         }
       }
@@ -276,15 +276,16 @@ QList< QPair<QgsVectorLayer *, int> > QgsVectorLayerAndAttributeModel::layers()
     {
       QgsVectorLayer *vl = qobject_cast< QgsVectorLayer *>( QgsLayerTree::toLayer( node )->layer() );
       Q_ASSERT( vl );
-      if ( !layerIdx.contains( vl ) )
+      if ( !layerIdx.contains( vl->id() ) )
       {
-        layerIdx.insert( vl, layers.size() );
+        layerIdx.insert( vl->id(), layers.size() );
         layers << qMakePair<QgsVectorLayer *, int>( vl, mAttributeIdx.value( vl, -1 ) );
       }
     }
   }
 
-  QList<QgsMapLayer*> inDrawingOrder = QgisApp::instance()->mapCanvas()->layers();
+  QgsLayerTreeMapCanvasBridge* bridge = QgisApp::instance()->layerTreeCanvasBridge();
+  QStringList inDrawingOrder = bridge->hasCustomLayerOrder() ? bridge->customLayerOrder() : bridge->defaultLayerOrder();
   QList< QPair<QgsVectorLayer *, int> > layersInROrder;
 
   for ( int i = inDrawingOrder.size() - 1; i >= 0; i-- )