#10195: Fix offsetline when the geometry is a polygon

Use GEOSBuffer in offsetline when the geometry is a polygon
qgis · Jun 11, 2014 · 3ca5706 · 3ca5706
1 parent f46053d
commit 3ca5706
Showing 1 changed file with 44 additions and 22 deletions.
diff --git a/src/core/symbology-ng/qgssymbollayerv2utils.cpp b/src/core/symbology-ng/qgssymbollayerv2utils.cpp
@@ -659,6 +659,27 @@ static QPointF linesIntersection( QPointF p1, double t1, QPointF p2, double t2 )
   y = p1.y() + t1 * ( x - p1.x() );
   return QPointF( x, y );
 }
+#else
+static QPolygonF makeOffsetGeometry( const QgsPolyline& polyline )
+{
+  int i, pointCount = polyline.count();
+
+  QPolygonF resultLine;
+  resultLine.resize( pointCount );
+
+  const QgsPoint* tempPtr = polyline.data();
+
+  for ( i = 0; i < pointCount; ++i, tempPtr++ )
+    resultLine[i] = QPointF( tempPtr->x(), tempPtr->y() );
+
+  return resultLine;
+}
+static QList<QPolygonF> makeOffsetGeometry( const QgsPolygon& polygon )
+{
+  QList<QPolygonF> resultGeom;
+  for ( int ring = 0; ring < polygon.size(); ++ring ) resultGeom.append( makeOffsetGeometry( polygon[ ring ] ) );
+  return resultGeom;
+}
 #endif
 
 
@@ -680,33 +701,33 @@ QList<QPolygonF> offsetLine( QPolygonF polyline, double dist )
 
   unsigned int i, pointCount = polyline.count();
 
+  bool isaLinearRing = false;
+  if ( polyline[0].x() == polyline[ pointCount - 1 ].x() && polyline[0].y() == polyline[ pointCount - 1 ].y() ) isaLinearRing = true;
+
   QgsPolyline tempPolyline( pointCount );
   QPointF* tempPtr = polyline.data();
   for ( i = 0; i < pointCount; ++i, tempPtr++ )
     tempPolyline[i] = QgsPoint( tempPtr->rx(), tempPtr->ry() );
 
-  QgsGeometry* tempGeometry = QgsGeometry::fromPolyline( tempPolyline );
+  QgsGeometry* tempGeometry = isaLinearRing ? QgsGeometry::fromPolygon( QgsPolygon() << tempPolyline ) : QgsGeometry::fromPolyline( tempPolyline );
   if ( tempGeometry )
   {
     const GEOSGeometry* geosGeom = tempGeometry->asGeos();
-    GEOSGeometry* offsetGeom = GEOSOffsetCurve( geosGeom, dist, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ );
+    GEOSGeometry* offsetGeom = isaLinearRing ? GEOSBuffer( geosGeom, -dist, 8 /*quadSegments*/ ) : GEOSOffsetCurve( geosGeom, dist, 8 /*quadSegments*/, 0 /*joinStyle*/, 5.0 /*mitreLimit*/ );
 
     if ( offsetGeom )
     {
       tempGeometry->fromGeos( offsetGeom );
 
       if ( QGis::flatType( tempGeometry->wkbType() ) == QGis::WKBLineString )
       {
-        tempPolyline = tempGeometry->asPolyline();
-
-        pointCount = tempPolyline.count();
-        newLine.resize( pointCount );
-
-        QgsPoint* tempPtr2 = tempPolyline.data();
-        for ( i = 0; i < pointCount; ++i, tempPtr2++ )
-          newLine[i] = QPointF( tempPtr2->x(), tempPtr2->y() );
-        resultLine.append( newLine );
-
+        resultLine.append( makeOffsetGeometry( tempGeometry->asPolyline() ) );
+        delete tempGeometry;
+        return resultLine;
+      }
+      else if ( QGis::flatType( tempGeometry->wkbType() ) == QGis::WKBPolygon )
+      {
+        resultLine.append( makeOffsetGeometry( tempGeometry->asPolygon() ) );
         delete tempGeometry;
         return resultLine;
       }
@@ -716,17 +737,18 @@ QList<QPolygonF> offsetLine( QPolygonF polyline, double dist )
 
         for ( int part = 0; part < tempMPolyline.count(); ++part )
         {
-          tempPolyline = tempMPolyline[ part ];
-
-          pointCount = tempPolyline.count();
-          newLine.resize( pointCount );
-
-          QgsPoint* tempPtr2 = tempPolyline.data();
-          for ( i = 0; i < pointCount; ++i, tempPtr2++ )
-            newLine[i] = QPointF( tempPtr2->x(), tempPtr2->y() );
-          resultLine.append( newLine );
+          resultLine.append( makeOffsetGeometry( tempMPolyline[ part ] ) );
+        }
+        delete tempGeometry;
+        return resultLine;
+      }
+      else if ( QGis::flatType( tempGeometry->wkbType() ) == QGis::WKBMultiPolygon )
+      {
+        QgsMultiPolygon tempMPolygon = tempGeometry->asMultiPolygon();
 
-          newLine = QPolygonF();
+        for ( int part = 0; part < tempMPolygon.count(); ++part )
+        {
+          resultLine.append( makeOffsetGeometry( tempMPolygon[ part ] ) );
         }
         delete tempGeometry;
         return resultLine;