Question

In my C#/XNA project, I have a “static” class that manages the input. It looks like this:

internal sealed class InputManager
{
    public delegate void KeyboardHandler(Actions action);

    public static event KeyboardHandler KeyPressed;

    private static readonly Dictionary<Actions, Keys> KeyBindings = Main.ContentManager.Load<Dictionary<Actions, Keys>>("KeyBindings");

    private static KeyboardState currentKeyboardState;

    private InputManager()
    {
    }

    public static void GetInput()
    {
        currentKeyboardState = Keyboard.GetState();

        foreach (KeyValuePair<Actions, Keys> actionKeyPair in KeyBindings)
        {
            if (currentKeyboardState.IsKeyDown(actionKeyPair.Value))
            {
                OnKeyPressed(actionKeyPair.Key);
            }
        }
    }

    private static void OnKeyPressed(Actions action)
    {
        if (KeyPressed != null)
        {
            KeyPressed(action);
        }
    }
}

So throughout the game, I get the input and check if any key contained in my dictionary is currently pressed (I use a dictionary for key binding purpose – an action is bound to a key). If so, the KeyPressed event is fired with the associated action as argument. By doing this I can subscribe an external class (such as a camera) to this event and do the appropriate thing based on the action (key).

The problem is that I have to test the action in every subscriber’s method like this:

        if (action == Actions.MoveLeft)
        {
            DoSomething();
        }

Hence, no matter which key is pressed (as long as it’s part of the dictionary) every subscriber’s method will be called even if it actually doesn’t need to.

I know I could set an event for each action : event MoveLeft, event MoveRight, etc… However, is there a better way to do this like a list of event?

Answer 1

you can use interface to deal with:
for instance:

interface IExecuteAction
{
void doMoveLeftAction();
void doMoveRightAction(); 
}

ExecuteMoveLeftAction(Actions action,IExecuteAction execAction)
{
switch(action
 case Actions.MoveLeft :
        execAction.doMoveLeftAction(); 
        break; 
case Actions.MoveLeft :
        execAction.doMoveLeftAction(); 
        break;
}

in your code implement this interface on your subscriber

class subscriber1:IExecuteAction
{
void doMoveLeftAction()
{
//do what you want
}
void doMoveRightAction()
 {
 //do what you want
 }
}

and after you handle like this:

ExecuteMoveLeftAction(action,subscriber1);