axiosengine/axios/ScreenSystem/InputAction.cs

97 lines
4.5 KiB
C#

#region File Description
//-----------------------------------------------------------------------------
// InputAction.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Input;
namespace GameStateManagement
{
/// <summary>
/// Defines an action that is designated by some set of buttons and/or keys.
///
/// The way actions work is that you define a set of buttons and keys that trigger the action. You can
/// then evaluate the action against an InputState which will test to see if any of the buttons or keys
/// are pressed by a player. You can also set a flag that indicates if the action only occurs once when
/// the buttons/keys are first pressed or whether the action should occur each frame.
///
/// Using this InputAction class means that you can configure new actions based on keys and buttons
/// without having to directly modify the InputState type. This means more customization by your games
/// without having to change the core classes of Game State Management.
/// </summary>
public class InputAction
{
private readonly Buttons[] buttons;
private readonly Keys[] keys;
private readonly bool newPressOnly;
// These delegate types map to the methods on InputState. We use these to simplify the evalute method
// by allowing us to map the appropriate delegates and invoke them, rather than having two separate code paths.
private delegate bool ButtonPress(Buttons button, PlayerIndex? controllingPlayer, out PlayerIndex player);
private delegate bool KeyPress(Keys key, PlayerIndex? controllingPlayer, out PlayerIndex player);
/// <summary>
/// Initializes a new InputAction.
/// </summary>
/// <param name="buttons">An array of buttons that can trigger the action.</param>
/// <param name="keys">An array of keys that can trigger the action.</param>
/// <param name="newPressOnly">Whether the action only occurs on the first press of one of the buttons/keys,
/// false if it occurs each frame one of the buttons/keys is down.</param>
public InputAction(Buttons[] buttons, Keys[] keys, bool newPressOnly)
{
// Store the buttons and keys. If the arrays are null, we create a 0 length array so we don't
// have to do null checks in the Evaluate method
this.buttons = buttons != null ? buttons.Clone() as Buttons[] : new Buttons[0];
this.keys = keys != null ? keys.Clone() as Keys[] : new Keys[0];
this.newPressOnly = newPressOnly;
}
/// <summary>
/// Evaluates the action against a given InputState.
/// </summary>
/// <param name="state">The InputState to test for the action.</param>
/// <param name="controllingPlayer">The player to test, or null to allow any player.</param>
/// <param name="player">If controllingPlayer is null, this is the player that performed the action.</param>
/// <returns>True if the action occurred, false otherwise.</returns>
public bool Evaluate(InputState state, PlayerIndex? controllingPlayer, out PlayerIndex player)
{
// Figure out which delegate methods to map from the state which takes care of our "newPressOnly" logic
ButtonPress buttonTest;
KeyPress keyTest;
if (newPressOnly)
{
buttonTest = state.IsNewButtonPress;
keyTest = state.IsNewKeyPress;
}
else
{
buttonTest = state.IsButtonPressed;
keyTest = state.IsKeyPressed;
}
// Now we simply need to invoke the appropriate methods for each button and key in our collections
foreach (Buttons button in buttons)
{
if (buttonTest(button, controllingPlayer, out player))
return true;
}
foreach (Keys key in keys)
{
if (keyTest(key, controllingPlayer, out player))
return true;
}
// If we got here, the action is not matched
player = PlayerIndex.One;
return false;
}
}
}