Fix line pattern fill offsets are always treated as positive,

even when offset is negative

(cherry picked from commit 5b4ed16)

src/core/symbology-ng/qgsfillsymbollayerv2.cpp

@@ -2650,7 +2650,7 @@ void QgsLinePatternFillSymbolLayer::applyPattern( const QgsSymbolV2RenderContext
 
     // Round offset to correspond to one pixel height, otherwise lines may
     // be shifted on tile border if offset falls close to pixel center
-    int offsetHeight = qRound( qAbs( outputPixelOffset / cos( lineAngle * M_PI / 180 ) ) );
+    int offsetHeight = qRound( outputPixelOffset / cos( lineAngle * M_PI / 180 ) );
     outputPixelOffset = offsetHeight * cos( lineAngle * M_PI / 180 );
   }
 

tests/src/core/testqgslinefillsymbol.cpp

@@ -60,6 +60,8 @@ class TestQgsLineFillSymbol : public QObject
     void cleanup() {} // will be called after every testfunction.
 
     void lineFillSymbol();
+    void lineFillSymbolOffset();
+
     void dataDefinedSubSymbol();
 
   private:
@@ -147,6 +149,18 @@ void TestQgsLineFillSymbol::lineFillSymbol()
   QVERIFY( imageCheck( "symbol_linefill" ) );
 }
 
+void TestQgsLineFillSymbol::lineFillSymbolOffset()
+{
+  mReport += QLatin1String( "<h2>Line fill symbol renderer test</h2>\n" );
+
+  mLineFill->setOffset( 0.5 );
+  QVERIFY( imageCheck( "symbol_linefill_posoffset" ) );
+
+  mLineFill->setOffset( -0.5 );
+  QVERIFY( imageCheck( "symbol_linefill_negoffset" ) );
+  mLineFill->setOffset( 0 );
+}
+
 void TestQgsLineFillSymbol::dataDefinedSubSymbol()
 {
   mReport += "<h2>Line fill symbol data defined sub symbol test</h2>\n";