Support assigning functions to hotkeys from the JS GUI without involving a GUI object.

Allows developers and modders to register and unregister hotkeys without
having to specify, change or overwrite XML files.
Also allows implementing the main menu GUI page with only GUI objects
for one submenu, refs #5387 / D2240.

Differential Revision: https://code.wildfiregames.com/D2260
Idea by nani in D2257.

This was SVN commit r22851.

source/gui/CGUI.cpp

@@ -71,6 +71,18 @@ InReaction CGUI::HandleEvent(const SDL_Event_* ev)
 	{
 		const char* hotkey = static_cast<const char*>(ev->ev.user.data1);
 
+		if (m_GlobalHotkeys.count(hotkey))
+		{
+			HotkeyInputHandler(ev);
+			ret = IN_HANDLED;
+
+			JSContext* cx = m_ScriptInterface->GetContext();
+			JSAutoRequest rq(cx);
+			JS::RootedObject globalObj(cx, &GetGlobalObject().toObject());
+			JS::RootedValue result(cx);
+			JS_CallFunctionValue(cx, globalObj, m_GlobalHotkeys[hotkey], JS::HandleValueArray::empty(), &result);
+		}
+
 		std::map<CStr, std::vector<IGUIObject*> >::iterator it = m_HotkeyObjects.find(hotkey);
 		if (it != m_HotkeyObjects.end())
 			for (IGUIObject* const& obj : it->second)
@@ -488,6 +500,32 @@ void CGUI::UnsetObjectHotkey(IGUIObject* pObject, const CStr& hotkeyTag)
 		assignment.end());
 }
 
+void CGUI::SetGlobalHotkey(const CStr& hotkeyTag, JS::HandleValue function)
+{
+	JSContext* cx = m_ScriptInterface->GetContext();
+	JSAutoRequest rq(cx);
+
+	if (hotkeyTag.empty())
+	{
+		JS_ReportError(cx, "Cannot assign a function to an empty hotkey identifier!");
+		return;
+	}
+
+	if (!function.isObject() || !JS_ObjectIsFunction(cx, &function.toObject()))
+	{
+		JS_ReportError(cx, "Cannot assign non-function value to global hotkey '%s'", hotkeyTag.c_str());
+		return;
+	}
+
+	UnsetGlobalHotkey(hotkeyTag);
+	m_GlobalHotkeys[hotkeyTag].init(cx, function);
+}
+
+void CGUI::UnsetGlobalHotkey(const CStr& hotkeyTag)
+{
+	m_GlobalHotkeys.erase(hotkeyTag);
+}
+
 const SGUIScrollBarStyle* CGUI::GetScrollBarStyle(const CStr& style) const
 {
 	std::map<CStr, const SGUIScrollBarStyle>::const_iterator it = m_ScrollBarStyles.find(style);