Add setBackgroundColor support

include/QtNodes/internal/NodeDelegateModel.hpp

@@ -4,6 +4,7 @@
 
 #include <QMetaType>
 #include <QPixmap>
+#include <QtGui/QColor>
 #include <QtWidgets/QWidget>
 
 #include "Definitions.hpp"
@@ -103,6 +104,9 @@ class NODE_EDITOR_PUBLIC NodeDelegateModel
 
     void setNodeStyle(NodeStyle const &style);
 
+    /// Convenience helper to change the node background color.
+    void setBackgroundColor(QColor const &color);
+
     QPixmap processingStatusIcon() const;
 
     void setStatusIcon(NodeProcessingStatus status, const QPixmap &pixmap);

include/QtNodes/internal/NodeStyle.hpp

@@ -46,6 +46,12 @@ class NODE_EDITOR_PUBLIC NodeStyle : public Style
 
     QJsonObject toJson() const override;
 
+    /// Set uniform background color for the node.
+    void setBackgroundColor(QColor const &color);
+
+    /// Current uniform background color.
+    QColor backgroundColor() const;
+
 public:
     QColor NormalBoundaryColor;
     QColor SelectedBoundaryColor;

src/NodeDelegateModel.cpp

@@ -115,4 +115,9 @@ void NodeDelegateModel::setNodeProcessingStatus(NodeProcessingStatus status)
     _processingStatus = status;
 }
 
+void NodeDelegateModel::setBackgroundColor(QColor const &color)
+{
+    _nodeStyle.setBackgroundColor(color);
+}
+
 } // namespace QtNodes

src/NodeStyle.cpp

@@ -156,3 +156,16 @@ QJsonObject NodeStyle::toJson() const
 
     return root;
 }
+
+void NodeStyle::setBackgroundColor(QColor const &color)
+{
+    GradientColor0 = color;
+    GradientColor1 = color;
+    GradientColor2 = color;
+    GradientColor3 = color;
+}
+
+QColor NodeStyle::backgroundColor() const
+{
+    return GradientColor0;
+}