logic: Show inheritance edges between parents of active symbol and other visible symbols (issue #167)

* add inheritance edges between parents of active symbol and other visible symbols
* add dashed inheritance edges when symbols are no direct decendants
* inheritance edges are also respected in layouting, putting base/derived classes in the correct top/bottom spot now

bug id = 167

src/lib_gui/qt/graphics/QtLineItemAngled.cpp

@@ -32,7 +32,8 @@ QPainterPath QtLineItemAngled::shape() const
 
 void QtLineItemAngled::paint(QPainter* painter, const QStyleOptionGraphicsItem* options, QWidget* widget)
 {
-	painter->setPen(pen());
+	QPen p = pen();
+	painter->setPen(p);
 
 	QPainterPath path;
 
@@ -169,7 +170,17 @@ void QtLineItemAngled::paint(QPainter* painter, const QStyleOptionGraphicsItem*
 		partRect = getArrowBoundingRect(poly);
 		if (drawRect.intersects(partRect) && m_showArrow)
 		{
-			drawArrow(poly, &path);
+			if (m_style.dashed)
+			{
+				QPainterPath arrowPath;
+				drawArrow(poly, &path, &arrowPath);
+
+				painter->drawPath(arrowPath);
+			}
+			else
+			{
+				drawArrow(poly, &path);
+			}
 		}
 		else
 		{
@@ -177,5 +188,11 @@ void QtLineItemAngled::paint(QPainter* painter, const QStyleOptionGraphicsItem*
 		}
 	}
 
+	if (m_style.dashed)
+	{
+		p.setStyle(Qt::DashLine);
+		painter->setPen(p);
+	}
+
 	painter->drawPath(path);
 }

src/lib_gui/qt/graphics/QtLineItemBase.cpp

@@ -336,7 +336,7 @@ QRectF QtLineItemBase::getArrowBoundingRect(const QPolygon& poly) const
 	return rect;
 }
 
-void QtLineItemBase::drawArrow(const QPolygon& poly, QPainterPath* path) const
+void QtLineItemBase::drawArrow(const QPolygon& poly, QPainterPath* path, QPainterPath* arrowPath) const
 {
 	int dir = getDirection(poly.at(1), poly.at(0));
 
@@ -364,7 +364,6 @@ void QtLineItemBase::drawArrow(const QPolygon& poly, QPainterPath* path) const
 		break;
 	}
 
-
 	if (m_style.arrowClosed)
 	{
 		path->lineTo(tip + toBack);
@@ -375,6 +374,12 @@ void QtLineItemBase::drawArrow(const QPolygon& poly, QPainterPath* path) const
 		path->lineTo(tip);
 	}
 
+	if (arrowPath)
+	{
+		path = arrowPath;
+		path->moveTo(tip);
+	}
+
 	path->lineTo(tip + toBack + toLeft);
 
 	if (m_style.arrowClosed)

src/lib_gui/qt/graphics/QtLineItemBase.h

@@ -45,7 +45,7 @@ protected:
 	int getDirection(const QPointF& a, const QPointF& b) const;
 
 	QRectF getArrowBoundingRect(const QPolygon& poly) const;
-	void drawArrow(const QPolygon& poly, QPainterPath* path) const;
+	void drawArrow(const QPolygon& poly, QPainterPath* path, QPainterPath* arrowPath = nullptr) const;
 
 	void getPivotPoints(Vec2f* p, const Vec4i& in, const Vec4i& out, int offset, bool target) const;