add Connection Line Arrow

examples/styles/main.cpp

@@ -77,7 +77,9 @@ static void setStyle()
       "ConstructionLineWidth": 2.0,
       "PointDiameter": 10.0,
 
-      "UseDataDefinedColors": false
+      "UseDataDefinedColors": false,
+      "InArrow" : true,
+       "OutArrow" : false
     }
   }
   )");

include/QtNodes/internal/ConnectionStyle.hpp

@@ -37,13 +37,17 @@ class NODE_EDITOR_PUBLIC ConnectionStyle : public Style
     float pointDiameter() const;
 
     bool useDataDefinedColors() const;
+    bool inArrow() const;
+    bool outArrow() const;
 
 private:
     QColor ConstructionColor;
     QColor NormalColor;
     QColor SelectedColor;
     QColor SelectedHaloColor;
     QColor HoveredColor;
+    bool InArrow;
+    bool OutArrow;
 
     float LineWidth;
     float ConstructionLineWidth;

src/ConnectionStyle.cpp

@@ -120,6 +120,8 @@ void ConnectionStyle::loadJson(QJsonObject const &json)
     CONNECTION_STYLE_READ_FLOAT(obj, PointDiameter);
 
     CONNECTION_STYLE_READ_BOOL(obj, UseDataDefinedColors);
+    CONNECTION_STYLE_READ_BOOL(obj, InArrow);
+    CONNECTION_STYLE_READ_BOOL(obj, OutArrow);
 }
 
 QJsonObject ConnectionStyle::toJson() const
@@ -137,6 +139,8 @@ QJsonObject ConnectionStyle::toJson() const
     CONNECTION_STYLE_WRITE_FLOAT(obj, PointDiameter);
 
     CONNECTION_STYLE_WRITE_BOOL(obj, UseDataDefinedColors);
+    CONNECTION_STYLE_WRITE_BOOL(obj, InArrow);
+    CONNECTION_STYLE_WRITE_BOOL(obj, OutArrow);
 
     QJsonObject root;
     root["ConnectionStyle"] = obj;
@@ -203,3 +207,13 @@ bool ConnectionStyle::useDataDefinedColors() const
 {
     return UseDataDefinedColors;
 }
+
+
+bool ConnectionStyle::inArrow() const
+{
+    return InArrow;
+}
+bool ConnectionStyle::outArrow() const
+{
+    return OutArrow;
+}

src/DefaultConnectionPainter.cpp

@@ -26,7 +26,7 @@ QPainterPath DefaultConnectionPainter::cubicPath(ConnectionGraphicsObject const
     return cubic;
 }
 
-void DefaultConnectionPainter::drawSketchLine(QPainter *painter, ConnectionGraphicsObject const &cgo) const
+void DefaultConnectionPainter::drawSketchLine(QPainter *painter, ConnectionGraphicsObject const &cgo, QPainterPath const &cubic) const
 {
     ConnectionState const &state = cgo.connectionState();
 
@@ -40,15 +40,12 @@ void DefaultConnectionPainter::drawSketchLine(QPainter *painter, ConnectionGraph
 
         painter->setPen(pen);
         painter->setBrush(Qt::NoBrush);
-
-        auto cubic = cubicPath(cgo);
-
         // cubic spline
         painter->drawPath(cubic);
     }
 }
 
-void DefaultConnectionPainter::drawHoveredOrSelected(QPainter *painter, ConnectionGraphicsObject const &cgo) const
+void DefaultConnectionPainter::drawHoveredOrSelected(QPainter *painter, ConnectionGraphicsObject const &cgo,  QPainterPath const &cubic) const
 {
     bool const hovered = cgo.connectionState().hovered();
     bool const selected = cgo.isSelected();
@@ -68,12 +65,11 @@ void DefaultConnectionPainter::drawHoveredOrSelected(QPainter *painter, Connecti
         painter->setBrush(Qt::NoBrush);
 
         // cubic spline
-        auto const cubic = cubicPath(cgo);
         painter->drawPath(cubic);
     }
 }
 
-void DefaultConnectionPainter::drawNormalLine(QPainter *painter, ConnectionGraphicsObject const &cgo) const
+void DefaultConnectionPainter::drawNormalLine(QPainter *painter, ConnectionGraphicsObject const &cgo, QPainterPath const &cubic) const
 {
     ConnectionState const &state = cgo.connectionState();
 
@@ -126,7 +122,6 @@ void DefaultConnectionPainter::drawNormalLine(QPainter *painter, ConnectionGraph
 
     bool const selected = cgo.isSelected();
 
-    auto cubic = cubicPath(cgo);
     if (useGradientColor) {
         painter->setBrush(Qt::NoBrush);
 
@@ -177,14 +172,15 @@ void DefaultConnectionPainter::drawNormalLine(QPainter *painter, ConnectionGraph
 
 void DefaultConnectionPainter::paint(QPainter *painter, ConnectionGraphicsObject const &cgo) const
 {
-    drawHoveredOrSelected(painter, cgo);
+    auto cubic = cubicPath(cgo);
+    drawHoveredOrSelected(painter, cgo,cubic);
 
-    drawSketchLine(painter, cgo);
+    drawSketchLine(painter, cgo,cubic);
 
-    drawNormalLine(painter, cgo);
+    drawNormalLine(painter, cgo,cubic);
 
 #ifdef NODE_DEBUG_DRAWING
-    debugDrawing(painter, cgo);
+    debugDrawing(painter, cgo,cubic);
 #endif
 
     // draw end points
@@ -195,8 +191,18 @@ void DefaultConnectionPainter::paint(QPainter *painter, ConnectionGraphicsObject
     painter->setPen(connectionStyle.constructionColor());
     painter->setBrush(connectionStyle.constructionColor());
     double const pointRadius = pointDiameter / 2.0;
-    painter->drawEllipse(cgo.out(), pointRadius, pointRadius);
-    painter->drawEllipse(cgo.in(), pointRadius, pointRadius);
+    if(connectionStyle.outArrow()) {
+        auto out = createArrowPoly(cubic,pointRadius,pointDiameter * 1.5,false);
+        painter->drawPolygon(out);
+    } else {
+        painter->drawEllipse(cgo.out(), pointRadius, pointRadius);
+    }
+    if(connectionStyle.inArrow()) {
+        auto in = createArrowPoly(cubic,pointRadius,pointDiameter * 1.5,true);
+        painter->drawPolygon(in);
+    } else {
+        painter->drawEllipse(cgo.in(), pointRadius, pointRadius);
+    }
 }
 
 QPainterPath DefaultConnectionPainter::getPainterStroke(ConnectionGraphicsObject const &connection) const
@@ -220,7 +226,7 @@ QPainterPath DefaultConnectionPainter::getPainterStroke(ConnectionGraphicsObject
 }
 
 #ifdef NODE_DEBUG_DRAWING
-void DefaultConnectionPainter::debugDrawing(QPainter *painter, ConnectionGraphicsObject const &cgo)
+void DefaultConnectionPainter::debugDrawing(QPainter *painter, ConnectionGraphicsObject const &cgo,QPainterPath const & cubic)
 {
     Q_UNUSED(painter);
 
@@ -240,7 +246,7 @@ void DefaultConnectionPainter::debugDrawing(QPainter *painter, ConnectionGraphic
         painter->drawEllipse(points.second, 3, 3);
 
         painter->setBrush(Qt::NoBrush);
-        painter->drawPath(cubicPath(cgo));
+        painter->drawPath(debugDrawing);
     }
 
     {
@@ -250,4 +256,28 @@ void DefaultConnectionPainter::debugDrawing(QPainter *painter, ConnectionGraphic
 }
 #endif
 
+QPolygonF DefaultConnectionPainter::createArrowPoly(const QPainterPath& p, double mRadius,double arrowSize,bool drawIn) {
+    float arrowStartPercentage;
+    float arrowEndPercentage;
+
+    if (drawIn) {
+        arrowStartPercentage = p.percentAtLength(p.length() - mRadius - arrowSize);
+        arrowEndPercentage = p.percentAtLength(p.length() - mRadius);
+    }
+    else {
+        arrowStartPercentage = p.percentAtLength(mRadius + arrowSize);
+        arrowEndPercentage = p.percentAtLength(mRadius);
+    }
+    QPointF headStartP = p.pointAtPercent(arrowStartPercentage);
+    QPointF headEndP = p.pointAtPercent(arrowEndPercentage);
+    QLineF arrowMiddleLine(headStartP, headEndP);
+    QPointF normHead(arrowMiddleLine.dy(), -arrowMiddleLine.dx());
+    QPointF arrowP1 = headStartP + normHead * 0.4;
+    QPointF arrowP2 = headStartP - normHead * 0.4;
+
+    QPolygonF arrowHeadEnd;
+    arrowHeadEnd << headEndP << arrowP1 << arrowP2 /*<< headEndP*/;
+    return arrowHeadEnd;
+}
+
 } // namespace QtNodes

src/DefaultConnectionPainter.hpp

@@ -16,13 +16,14 @@ class DefaultConnectionPainter : public AbstractConnectionPainter
 public:
     void paint(QPainter *painter, ConnectionGraphicsObject const &cgo) const override;
     QPainterPath getPainterStroke(ConnectionGraphicsObject const &cgo) const override;
+    static QPolygonF createArrowPoly(const QPainterPath& p, double mRadius,double arrowSize,bool drawIn = true);
 private:
     QPainterPath cubicPath(ConnectionGraphicsObject const &connection) const;
-    void drawSketchLine(QPainter *painter, ConnectionGraphicsObject const &cgo) const;
-    void drawHoveredOrSelected(QPainter *painter, ConnectionGraphicsObject const &cgo) const;
-    void drawNormalLine(QPainter *painter, ConnectionGraphicsObject const &cgo) const;
+    void drawSketchLine(QPainter *painter, ConnectionGraphicsObject const &cgo,QPainterPath const & cubic) const;
+    void drawHoveredOrSelected(QPainter *painter, ConnectionGraphicsObject const &cgo,QPainterPath const & cubic) const;
+    void drawNormalLine(QPainter *painter, ConnectionGraphicsObject const &cgo,QPainterPath const & cubic) const;
 #ifdef NODE_DEBUG_DRAWING
-    void debugDrawing(QPainter *painter, ConnectionGraphicsObject const &cgo) const;
+    void debugDrawing(QPainter *painter, ConnectionGraphicsObject const &cgo,QPainterPath const & cubic) const;
 #endif
 };
 

src/NodeGraphicsObject.cpp

@@ -78,7 +78,9 @@ BasicGraphicsScene *NodeGraphicsObject::nodeScene() const
 
 void NodeGraphicsObject::updateQWidgetEmbedPos()
 {
-    _proxyWidget->setPos(nodeScene()->nodeGeometry().widgetPosition(_nodeId));
+    if(_proxyWidget) {
+        _proxyWidget->setPos(nodeScene()->nodeGeometry().widgetPosition(_nodeId));
+    }
 }
 
 void NodeGraphicsObject::embedQWidget()