(svn r25263) -Add: legend for linkgraph overlay (fonsinchen)

src/linkgraph/linkgraph_gui.h

@@ -89,4 +89,25 @@ protected:
 	static void DrawVertex(int x, int y, int size, int colour, int border_colour);
 };
 
+void ShowLinkGraphLegend();
+
+/**
+ * Menu window to select cargoes and companies to show in a link graph overlay.
+ */
+struct LinkGraphLegendWindow : Window {
+public:
+	LinkGraphLegendWindow(const WindowDesc *desc, int window_number);
+	void SetOverlay(LinkGraphOverlay *overlay);
+
+	virtual void DrawWidget(const Rect &r, int widget) const;
+	virtual void OnClick(Point pt, int widget, int click_count);
+	virtual void OnInvalidateData(int data = 0, bool gui_scope = true);
+
+private:
+	LinkGraphOverlay *overlay;
+
+	void UpdateOverlayCompanies();
+	void UpdateOverlayCargoes();
+};
+
 #endif /* LINKGRAPH_GUI_H */