koobas.hobune.stream
Delegate an event
Hi everyone, I am new at Unity and want to learn the delegate event, but I have a problem. I want when the button has been clicked, it will show some GUI button on it. I already tried the delegate, but the event is not fired (I mean the GUI button is not shown).
Here is the code that I am using:
The code below is to show the GUI button when I run the game.
public class IItemDatabase : MonoBehaviour
{
public delegate void Action(); // Set the event for the button
public static event Action onClicked; // The event for when the button has been clicked
protected virtual void OnGUI()
{
// Call the SetStyle method
SetStyle();
// Set the GUIContent as the tooltip
GUIContent buttonText = new GUIContent("Open Shop");
// Set the GUIContent as the tooltip
GUIContent buttonTexts = new GUIContent("Open Inventory");
// This GUILayoutUtility is useful because it is to fit the content
Rect buttonGUI = GUILayoutUtility.GetRect(buttonText, "Button");
// This GUILayoutUtility is useful because it is to fit the content
Rect buttonGUIs = GUILayoutUtility.GetRect(buttonTexts, "Button");
// Set where have to the Rect displayed
buttonGUI.x = 5;
buttonGUI.y = Screen.height - 25;
// Set where have to the Rect displayed
buttonGUIs.x = 125;
buttonGUIs.y = Screen.height - 25;
// If the button has been clicked
if (GUI.Button(buttonGUI, buttonText, style))
{
if (onClicked != null)
{
onClicked();
}
}
if (GUI.Button(buttonGUIs, buttonTexts, style))
{
if (onClicked != null)
{
onClicked();
}
}
// End of the clicked button event
}
}
And here is the I want it to display when the button has been clicked:
public class IInventory : MonoBehaviour
{
protected virtual void OnEnable()
{
IItemDatabase.onClicked += DoGUI;
}
protected virtual void OnDisable()
{
IItemDatabase.onClicked -= DoGUI;
}
protected virtual void DoGUI()
{
Rect slotRect = new Rect(x * 35 + (Screen.width / 3) + 50, y * 35 + (Screen.height / 3) - 10, 30, 30);
GUI.Box(slotRect, GUIContent.none);
}
}
But when I clicked the button that it suppose to fired the DoGUI() in IInventory class, it does not run the function.
How do I solve this?
Thank you.
Your answer much appreciated!
I'm always happy to see questions about delegates :)
You seem to have the idea that a delegate and event are different things. An event is a delegate - only difference event has is there is an added layer of abstraction and security that makes it impossible to set the delegate value directly, instead you're only allowed to add/remove methods. In other words, with delegates it is possible to do: do myDel = value; and myDel X= value; (where X: - or +) But with events only myEvent X= value; is allowed (where X: - or +) A lot of times, the terms "event" and "delegate" are used interchangeably.
public delegate void Action(); // Set the event for the button
There's already a built-in delegate called Action for you in that exact signature (in the System namespace)
I ran your scripts and they worked fine. DoGUI did get executed.
I like what you're doing - You're following the single responsibility principle by indirectly having your buttons reference the inventory by using delegates - because it's not the button's responsibility to determine what happens in an inventory +1 However; I'm not very fond of the delegate being static. I suggest the following change of design: Create a Slot class that has an Item (if you wish) - The inventory will then have an aggregate (list) of Slots - Each Slot has an onClick - When the inventory creates a slot for ex, it subscribes itself to the slot's onClick so that when a slot/button is clicked, it indirectly notifies the inventory. No need for statics.
More delegate stuff:
If you want to learn everything about delegates (Actions, Funcs, Predicates, Anonymous methods, lamda expression, etc) and how they work, Jamie King is the best source.
See this answer here on how to make delegates survive an assembly reload.
For a full solution on serializable/inspectable delegate, see my uFAction.
Thank you so much for the answer (long answer :p) but it is very helpful for me vexe :D I appreciate that and will look at about your delegate stuff right now. Anyway, the script that has been posted in the question above is being simplified from what the my original script does (for the IInventory DoGUI function), I will look at where I have wrongly cause the DoGUI function is not executing after I look at your delegate stuff. Thank you so much once again :D
You do have both your scripts attached to gameObjects right? - Did you debug? if not, do so and do manual stepping. You could print the targets/methods of you delegate to see if the method is hooked or not:
foreach(var d in myDel.GetInvocationList())
Debug.Log("Target: " + d.Target + " $$anonymous$$ethod: " + d.$$anonymous$$ethod.Name);
Sorry for the late reply. Yes, I already tried to debug it and the method of the DoGUI is fired / called. But, the problem is the the Inventory inside DoGUI function is not show, even though the variable that held the Inventory to be shown already true.
Do I need to post the original code in here sir?
I will share the link in here.
Thank you :D
I already tried to debug it and the method of the DoGUI is fired / called. But, the problem is the the Inventory inside DoGUI function is not show
That means it's a problem wasn't with delegates to begin with. But with your GUI code. So you're saying, you're expecting your inventory to show up but it's not? How are you drawing it? Currently, all you have is just a GUI.Box
I don't do C# but don't you need to add the brackets to call a function?
DoGUI();
Yes he does. But if you're talking about this line:
IItemDatabase.onClicked += DoGUI;
Then no, he shouldn't be adding parentheses (not brackets btw ;) because he's not invoking the method he's just adding it to the delegate.
