Tidy up the User Interface example to pass a context instead of using globals,...

Tidy up the User Interface example to pass a context instead of using globals, and enumerate values instead of using magic numbers.  Just for niceness.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@1813 dfc29bdd-3216-0410-991c-e03cc46cb475

examples/05.UserInterface/main.cpp

@@ -25,11 +25,23 @@ using namespace gui;
 #pragma comment(lib, "Irrlicht.lib")
 #endif
 
+// Declare a structure to hold some context for the event receiver so that it
+// has it available inside its OnEvent() method.
+struct SAppContext
+{
+	IrrlichtDevice *device;
+	s32				counter;
+	IGUIListBox*	listbox;
+};
 
-IrrlichtDevice *device = 0;
-s32 cnt = 0;
-IGUIListBox* listbox = 0;
-
+// Define some values that we'll use to identify individual GUI controls.
+enum
+{
+	GUI_ID_QUIT_BUTTON = 101,
+	GUI_ID_NEW_WINDOW_BUTTON,
+	GUI_ID_FILE_OPEN_BUTTON,
+	GUI_ID_TRANSPARENCY_SCROLL_BAR
+};
 
 /*
 The Event Receiver is not only capable of getting keyboard and
@@ -45,26 +57,28 @@ the pointer to the gui environment.
 class MyEventReceiver : public IEventReceiver
 {
 public:
+	MyEventReceiver(SAppContext & context) : Context(context) { }
+
 	virtual bool OnEvent(const SEvent& event)
 	{
 		if (event.EventType == EET_GUI_EVENT)
 		{
 			s32 id = event.GUIEvent.Caller->getID();
-			IGUIEnvironment* env = device->getGUIEnvironment();
+			IGUIEnvironment* env = Context.device->getGUIEnvironment();
 
 			switch(event.GUIEvent.EventType)
 			{
 
 			/*
 			If a scrollbar changed its scroll position, and it is
-			'our' scrollbar (the one with id 104), then we change
+			'our' scrollbar (the one with id GUI_ID_TRANSPARENCY_SCROLL_BAR), then we change
 			the transparency of all gui elements. This is a very
 			easy task: There is a skin object, in which all color
 			settings are stored. We simply go through all colors
 			stored in the skin and change their alpha value.
 			*/
 			case EGET_SCROLL_BAR_CHANGED:
-				if (id == 104)
+				if (id == GUI_ID_TRANSPARENCY_SCROLL_BAR)
 				{
 					s32 pos = ((IGUIScrollBar*)event.GUIEvent.Caller)->getPos();
 					
@@ -88,22 +102,21 @@ public:
 			That's all for the event receiver.
 			*/
 			case EGET_BUTTON_CLICKED:
-
-				if (id == 101)
+				switch(id)
 				{
-					device->closeDevice();
+				case GUI_ID_QUIT_BUTTON:
+					Context.device->closeDevice();
 					return true;
-				}
 
-				if (id == 102)
+				case GUI_ID_NEW_WINDOW_BUTTON:
 					{
-					listbox->addItem(L"Window created");
-					cnt += 30;
-					if (cnt > 200)
-						cnt = 0;
+					Context.listbox->addItem(L"Window created");
+					Context.counter += 30;
+					if (Context.counter > 200)
+						Context.counter = 0;
 
 					IGUIWindow* window = env->addWindow(
-						rect<s32>(100 + cnt, 100 + cnt, 300 + cnt, 200 + cnt),
+						rect<s32>(100 + Context.counter, 100 + Context.counter, 300 + Context.counter, 200 + Context.counter),
 						false, // modal?
 						L"Test window");
 
@@ -112,18 +125,19 @@ public:
 						true, // border?
 						false, // wordwrap?
 						window);
-
-					return true;
 					}
+					return true;
 
-				if (id == 103)
-				{
-					listbox->addItem(L"File open");
+				case GUI_ID_FILE_OPEN_BUTTON:
+					Context.listbox->addItem(L"File open");
 					env->addFileOpenDialog(L"Please choose a file.");
 					return true;
-				}
 
+				default:
+					return false;
+				}
 				break;
+
 			default:
 				break;
 			}
@@ -131,6 +145,9 @@ public:
 
 		return false;
 	}
+
+private:
+	SAppContext & Context;
 };
 
 
@@ -166,7 +183,7 @@ int main()
 
 	// create device and exit if creation failed
 
-	device = createDevice(driverType, core::dimension2d<s32>(640, 480));
+	IrrlichtDevice * device = createDevice(driverType, core::dimension2d<s32>(640, 480));
 
 	if (device == 0)
 		return 1; // could not create selected driver.
@@ -174,8 +191,6 @@ int main()
 	/* The creation was successful, now we set the event receiver and
 		store pointers to the driver and to the gui environment. */
 
-	MyEventReceiver receiver;
-	device->setEventReceiver(&receiver);
 	device->setWindowCaption(L"Irrlicht Engine - User Interface Demo");
 
 	video::IVideoDriver* driver = device->getVideoDriver();
@@ -202,11 +217,11 @@ int main()
 	the button in the event receiver.
 	*/	
 
-	env->addButton(rect<s32>(10,240,110,240 + 32), 0, 101,
+	env->addButton(rect<s32>(10,240,110,240 + 32), 0, GUI_ID_QUIT_BUTTON,
 			L"Quit", L"Exits Program");
-	env->addButton(rect<s32>(10,280,110,280 + 32), 0, 102,
+	env->addButton(rect<s32>(10,280,110,280 + 32), 0, GUI_ID_NEW_WINDOW_BUTTON,
 			L"New Window", L"Launches a new Window");
-	env->addButton(rect<s32>(10,320,110,320 + 32), 0, 103,
+	env->addButton(rect<s32>(10,320,110,320 + 32), 0, GUI_ID_FILE_OPEN_BUTTON,
 			L"File Open", L"Opens a file");
 
 	/*
@@ -219,16 +234,29 @@ int main()
 
 	env->addStaticText(L"Transparent Control:", rect<s32>(150,20,350,40), true);
 	IGUIScrollBar* scrollbar = env->addScrollBar(true,
-			rect<s32>(150, 45, 350, 60), 0, 104);
+			rect<s32>(150, 45, 350, 60), 0, GUI_ID_TRANSPARENCY_SCROLL_BAR);
 	scrollbar->setMax(255);
 
 	// set scrollbar position to alpha value of an arbitrary element
 	scrollbar->setPos(env->getSkin()->getColor(EGDC_WINDOW).getAlpha());
 
 	env->addStaticText(L"Logging ListBox:", rect<s32>(50,110,250,130), true);
-	listbox = env->addListBox(rect<s32>(50, 140, 250, 210));
+	IGUIListBox * listbox = env->addListBox(rect<s32>(50, 140, 250, 210));
 	env->addEditBox(L"Editable Text", rect<s32>(350, 80, 550, 100));
 
+	// Store the appropriate data in a context structure.
+	SAppContext context;
+	context.device = device;
+	context.counter = 0;
+	context.listbox = listbox;
+
+	// Then create the event receiver, giving it that context structure.
+	MyEventReceiver receiver(context);
+
+	// And tell the device to use our custom event receiver.
+	device->setEventReceiver(&receiver);
+
+
 	/*
 	And at last, we create a nice Irrlicht Engine logo in the top left corner. 
 	*/