axiosengine/axios/ScreenSystem/MenuScreen.cs

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#region File Description
//-----------------------------------------------------------------------------
// MenuScreen.cs
//
// XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
#region Using Statements
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using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input.Touch;
using Microsoft.Xna.Framework.Input;
using FarseerPhysics.SamplesFramework;
#endregion
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namespace GameStateManagement
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{
/// <summary>
/// Base class for screens that contain a menu of options. The user can
/// move up and down to select an entry, or cancel to back out of the screen.
/// </summary>
public class MenuScreen : GameScreen
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{
#region Fields
private List<MenuEntry> menuEntries = new List<MenuEntry>();
int selectedEntry = 0;
string menuTitle;
InputAction menuUp;
InputAction menuDown;
InputAction menuSelect;
InputAction menuCancel;
#endregion
#region Properties
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/// <summary>
/// Gets the list of menu entries, so derived classes can add
/// or change the menu contents.
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/// </summary>
protected IList<MenuEntry> MenuEntries
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{
get { return menuEntries; }
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}
#endregion
#region Initialization
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/// <summary>
/// Constructor.
/// </summary>
public MenuScreen(string menuTitle)
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{
this.menuTitle = menuTitle;
TransitionOnTime = TimeSpan.FromSeconds(0.5);
TransitionOffTime = TimeSpan.FromSeconds(0.5);
menuUp = new InputAction(
new Buttons[] { Buttons.DPadUp, Buttons.LeftThumbstickUp },
new Keys[] { Keys.Up },
true);
menuDown = new InputAction(
new Buttons[] { Buttons.DPadDown, Buttons.LeftThumbstickDown },
new Keys[] { Keys.Down },
true);
menuSelect = new InputAction(
new Buttons[] { Buttons.A, Buttons.Start },
new Keys[] { Keys.Enter, Keys.Space },
true);
menuCancel = new InputAction(
new Buttons[] { Buttons.B, Buttons.Back },
new Keys[] { Keys.Escape },
true);
}
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#endregion
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public void AddMenuItem(string name)
{
menuEntries.Add(new MenuEntry(name));
}
#region Handle Input
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/// <summary>
/// Responds to user input, changing the selected entry and accepting
/// or cancelling the menu.
/// </summary>
public override void HandleInput(GameTime gameTime, InputState input)
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{
// For input tests we pass in our ControllingPlayer, which may
// either be null (to accept input from any player) or a specific index.
// If we pass a null controlling player, the InputState helper returns to
// us which player actually provided the input. We pass that through to
// OnSelectEntry and OnCancel, so they can tell which player triggered them.
PlayerIndex playerIndex;
// Move to the previous menu entry?
if (menuUp.Evaluate(input, ControllingPlayer, out playerIndex))
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{
selectedEntry--;
if (selectedEntry < 0)
selectedEntry = menuEntries.Count - 1;
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}
// Move to the next menu entry?
if (menuDown.Evaluate(input, ControllingPlayer, out playerIndex))
{
selectedEntry++;
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if (selectedEntry >= menuEntries.Count)
selectedEntry = 0;
}
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if (menuSelect.Evaluate(input, ControllingPlayer, out playerIndex))
{
OnSelectEntry(selectedEntry, playerIndex);
}
else if (menuCancel.Evaluate(input, ControllingPlayer, out playerIndex))
{
OnCancel(playerIndex);
}
}
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/// <summary>
/// Handler for when the user has chosen a menu entry.
/// </summary>
protected virtual void OnSelectEntry(int entryIndex, PlayerIndex playerIndex)
{
menuEntries[entryIndex].OnSelectEntry(playerIndex);
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}
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/// <summary>
/// Handler for when the user has cancelled the menu.
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/// </summary>
protected virtual void OnCancel(PlayerIndex playerIndex)
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{
ExitScreen();
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}
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/// <summary>
/// Helper overload makes it easy to use OnCancel as a MenuEntry event handler.
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/// </summary>
protected void OnCancel(object sender, PlayerIndexEventArgs e)
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{
OnCancel(e.PlayerIndex);
}
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#endregion
#region Update and Draw
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/// <summary>
/// Allows the screen the chance to position the menu entries. By default
/// all menu entries are lined up in a vertical list, centered on the screen.
/// </summary>
protected virtual void UpdateMenuEntryLocations()
{
// Make the menu slide into place during transitions, using a
// power curve to make things look more interesting (this makes
// the movement slow down as it nears the end).
float transitionOffset = (float)Math.Pow(TransitionPosition, 2);
// start at Y = 175; each X value is generated per entry
Vector2 position = new Vector2(0f, 175f);
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// update each menu entry's location in turn
for (int i = 0; i < menuEntries.Count; i++)
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{
MenuEntry menuEntry = menuEntries[i];
// each entry is to be centered horizontally
position.X = ScreenManager.GraphicsDevice.Viewport.Width / 2 - menuEntry.GetWidth(this) / 2;
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if (ScreenState == ScreenState.TransitionOn)
position.X -= transitionOffset * 256;
else
position.X += transitionOffset * 512;
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// set the entry's position
menuEntry.Position = position;
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// move down for the next entry the size of this entry
position.Y += menuEntry.GetHeight(this);
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}
}
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/// <summary>
/// Updates the menu.
/// </summary>
public override void Update(GameTime gameTime, bool otherScreenHasFocus,
bool coveredByOtherScreen)
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{
base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen);
// Update each nested MenuEntry object.
for (int i = 0; i < menuEntries.Count; i++)
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{
bool isSelected = IsActive && (i == selectedEntry);
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menuEntries[i].Update(this, isSelected, gameTime);
}
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}
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/// <summary>
/// Draws the menu.
/// </summary>
public override void Draw(GameTime gameTime)
{
// make sure our entries are in the right place before we draw them
UpdateMenuEntryLocations();
GraphicsDevice graphics = ScreenManager.GraphicsDevice;
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SpriteBatch spriteBatch = ScreenManager.SpriteBatch;
SpriteFont font = ScreenManager.Font;
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spriteBatch.Begin();
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// Draw each menu entry in turn.
for (int i = 0; i < menuEntries.Count; i++)
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{
MenuEntry menuEntry = menuEntries[i];
bool isSelected = IsActive && (i == selectedEntry);
menuEntry.Draw(this, isSelected, gameTime);
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}
// Make the menu slide into place during transitions, using a
// power curve to make things look more interesting (this makes
// the movement slow down as it nears the end).
float transitionOffset = (float)Math.Pow(TransitionPosition, 2);
// Draw the menu title centered on the screen
Vector2 titlePosition = new Vector2(graphics.Viewport.Width / 2, 80);
Vector2 titleOrigin = font.MeasureString(menuTitle) / 2;
Color titleColor = new Color(192, 192, 192) * TransitionAlpha;
float titleScale = 1.25f;
titlePosition.Y -= transitionOffset * 100;
spriteBatch.DrawString(font, menuTitle, titlePosition, titleColor, 0,
titleOrigin, titleScale, SpriteEffects.None, 0);
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spriteBatch.End();
}
#endregion
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}
}