dxf export:

* switch to rgb colors only (fixes black/white issues)
* fix drawing of polygon outlines
* distiguish polygon outlines from filled polygons in paint engine
  (fixes #12368)

(cherry picked from commit 25e4e4d)

Author: jef-n

src/core/dxf/qgsdxfexport.cpp

@@ -418,6 +418,7 @@ void QgsDxfExport::writeGroup( int code, const QgsPoint &p, double z, bool skipz
 
 void QgsDxfExport::writeGroup( QColor color, int exactMatchCode, int rgbCode, int transparencyCode )
 {
+#if 0
   int minDistAt = -1;
   int minDist = INT_MAX;
 
@@ -437,6 +438,7 @@ void QgsDxfExport::writeGroup( QColor color, int exactMatchCode, int rgbCode, in
     // exact full opaque match
     return;
   }
+#endif
 
   int c = ( color.red() & 0xff ) * 0x10000 + ( color.green() & 0xff ) * 0x100 + ( color.blue() & 0xff );
   writeGroup( rgbCode, c );
@@ -3694,7 +3696,7 @@ void QgsDxfExport::addFeature( const QgsSymbolV2RenderContext& ctx, const QStrin
       QgsPolygon::const_iterator polyIt = polygon.constBegin();
       for ( ; polyIt != polygon.constEnd(); ++polyIt ) // iterate over rings
       {
-        writePolyline( geom->asPolyline(), layer, lineStyleName, penColor, width, false );
+        writePolyline( *polyIt, layer, lineStyleName, penColor, width, false );
       }
 
       if ( offsetPolygon != geom )

src/core/dxf/qgsdxfpaintengine.cpp

@@ -84,12 +84,19 @@ void QgsDxfPaintEngine::drawPolygon( const QPointF *points, int pointCount, Poly
     polyline[i] = toDxfCoordinates( points[i] );
   }
 
-  mDxf->writePolygon( polygon, mLayer, "SOLID", currentColor() );
+  if ( mode == QPaintEngine::PolylineMode )
+  {
+    mDxf->writePolyline( polyline, mLayer, "CONTINUOUS", mPen.color(), currentWidth(), true );
+  }
+  else
+  {
+    mDxf->writePolygon( polygon, mLayer, "SOLID", mBrush.color() );
+  }
 }
 
 void QgsDxfPaintEngine::drawRects( const QRectF* rects, int rectCount )
 {
-  if ( !mDxf || !mPaintDevice || !rects )
+  if ( !mDxf || !mPaintDevice || !rects || mBrush.style() == Qt::NoBrush )
   {
     return;
   }
@@ -104,7 +111,7 @@ void QgsDxfPaintEngine::drawRects( const QRectF* rects, int rectCount )
     QgsPoint pt2 = toDxfCoordinates( QPointF( right, bottom ) );
     QgsPoint pt3 = toDxfCoordinates( QPointF( left, top ) );
     QgsPoint pt4 = toDxfCoordinates( QPointF( right, top ) );
-    mDxf->writeSolid( mLayer, currentColor(), pt1, pt2, pt3, pt4 );
+    mDxf->writeSolid( mLayer, mBrush.color(), pt1, pt2, pt3, pt4 );
   }
 }
 
@@ -162,7 +169,10 @@ void QgsDxfPaintEngine::endPolygon()
 {
   if ( mCurrentPolygon.size() > 1 )
   {
-    drawPolygon( mCurrentPolygon.constData(), mCurrentPolygon.size(), QPaintEngine::OddEvenMode );
+    if ( mPen.style() != Qt::NoPen )
+      drawPolygon( mCurrentPolygon.constData(), mCurrentPolygon.size(), QPaintEngine::PolylineMode );
+    if ( mBrush.style() != Qt::NoBrush )
+      drawPolygon( mCurrentPolygon.constData(), mCurrentPolygon.size(), QPaintEngine::OddEvenMode );
   }
   mCurrentPolygon.clear();
 }
@@ -198,7 +208,7 @@ void QgsDxfPaintEngine::endCurve()
 
 void QgsDxfPaintEngine::drawLines( const QLineF* lines, int lineCount )
 {
-  if ( !mDxf || !mPaintDevice || !lines )
+  if ( !mDxf || !mPaintDevice || !lines || mPen.style() == Qt::NoPen )
   {
     return;
   }
@@ -207,7 +217,7 @@ void QgsDxfPaintEngine::drawLines( const QLineF* lines, int lineCount )
   {
     QgsPoint pt1 = toDxfCoordinates( lines[i].p1() );
     QgsPoint pt2 = toDxfCoordinates( lines[i].p2() );
-    mDxf->writeLine( pt1, pt2, mLayer, "CONTINUOUS", currentColor(), currentWidth() );
+    mDxf->writeLine( pt1, pt2, mLayer, "CONTINUOUS", mPen.color(), currentWidth() );
   }
 }
 
@@ -222,20 +232,6 @@ QgsPoint QgsDxfPaintEngine::toDxfCoordinates( const QPointF& pt ) const
   return QgsPoint( dxfPt.x(), dxfPt.y() );
 }
 
-QColor QgsDxfPaintEngine::currentColor() const
-{
-  if ( !mDxf )
-  {
-    return QColor();
-  }
-
-  QColor c = mPen.color();
-  if ( mPen.style() == Qt::NoPen )
-  {
-    c = mBrush.color();
-  }
-  return c;
-}
 
 double QgsDxfPaintEngine::currentWidth() const
 {

src/core/dxf/qgsdxfpaintengine.h

@@ -61,7 +61,6 @@ class CORE_EXPORT QgsDxfPaintEngine: public QPaintEngine
     QList<QPointF> mCurrentCurve;
 
     QgsPoint toDxfCoordinates( const QPointF& pt ) const;
-    QColor currentColor() const;
     double currentWidth() const;
 
     void moveTo( double dx, double dy );