XNA之RPG游戏开发教程之六

本节的任务有两点：1、创建一个新控件，实现角色的选择；具体操作要求是按左键，呈现上一个角色信息，按右键呈现下一个角色信息；2、创建一个角色选择页面，将新控件添加进去

首先开始第一个任务，前面已经创建了控件基类Control类和控件管理类ControlManager类，新的控件要继承基类，并在页面实例化后要添加进管理类中便于操作管理。新控件LeftRightSelector，一个向左向右可选择控件的代码实现如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
namespace XRpgLibrary.Controls
{
public class LeftRightSelector : Control
 {
 #region Event Region
public event EventHandler SelectionChanged;//控件选择更改事件
 #endregion
 #region Field Region
List<string> items = new List<string>();//控件中呈现字符串集合
Texture2D leftTexture;//表示向左，向右，尽头终止的图片
Texture2D rightTexture;
Texture2D stopTexture;
Color selectedColor = Color.Red;//被选字符串呈现红色
int maxItemWidth;//字符串项的最大宽度
int selectedItem;//被选择的项索引
 #endregion
 #region Property Region
public Color SelectedColor
 {
  get { return selectedColor; }
  set { selectedColor = value; }
 }
public int SelectedIndex
 {
  get { return selectedItem; }
  set { selectedItem = (int)MathHelper.Clamp(value, 0f, items.Count); }
 }
public string SelectedItem
 {
  get { return Items[selectedItem]; }
 }
public List<string> Items
 {
  get { return items; }
 }
 #endregion
 #region Constructor Region
public LeftRightSelector(Texture2D leftArrow, Texture2D rightArrow, Texture2D stop)
 {
 leftTexture = leftArrow;
 rightTexture = rightArrow;
 stopTexture = stop;
 TabStop = true;
 Color = Color.White;
 }
 #endregion
 #region Method Region为字符串序列和字符串最大宽度赋值
public void SetItems(string[] items, int maxWidth)
 {
 this.items.Clear();
 foreach (string s in items)
 this.items.Add(s);
 maxItemWidth = maxWidth;
 }
//事件触发函数
protected void OnSelectionChanged()
 {
  if (SelectionChanged != null)
 {
   SelectionChanged(this, null);
 }
 }
 #endregion
 #region Abstract Method Region
public override void Update(GameTime gameTime)
 {
 }
public override void Draw(SpriteBatch spriteBatch)
 {
  Vector2 drawTo = position;
  if (selectedItem != 0)
   spriteBatch.Draw(leftTexture, drawTo, Color.White);
  else
   spriteBatch.Draw(stopTexture, drawTo, Color.White);
  drawTo.X += leftTexture.Width + 5f;
  float itemWidth = spriteFont.MeasureString(items[selectedItem]).X;
  float offset = (maxItemWidth - itemWidth) / 2;
  drawTo.X += offset;
  if (hasFocus)
    spriteBatch.DrawString(spriteFont, items[selectedItem], drawTo, selectedColor);
  else
    spriteBatch.DrawString(spriteFont, items[selectedItem], drawTo, Color);
  drawTo.X += -1 * offset + maxItemWidth + 5f;
  if (selectedItem != items.Count - 1)
    spriteBatch.Draw(rightTexture, drawTo, Color.White);
  else
    spriteBatch.Draw(stopTexture, drawTo, Color.White);
 }
public override void HandleInput(PlayerIndex playerIndex)
 {
  if (items.Count == 0)
   return;
  if (InputHandler.ButtonReleased(Buttons.LeftThumbstickLeft, playerIndex) ||
   InputHandler.ButtonReleased(Buttons.DPadLeft, playerIndex) ||
   InputHandler.KeyReleased(Keys.Left))
 {
 selectedItem--;
if (selectedItem < 0)
 selectedItem = 0;
 OnSelectionChanged();//触发事件
 }
if (InputHandler.ButtonReleased(Buttons.LeftThumbstickRight, playerIndex) ||
InputHandler.ButtonReleased(Buttons.DPadRight, playerIndex) ||
InputHandler.KeyReleased(Keys.Right))
 {
 selectedItem++;
if (selectedItem >= items.Count)
 selectedItem = items.Count - 1;
 OnSelectionChanged();
 }
 }
 #endregion
 }
}

接着就是添加一个新的游戏页面，用来选取角色信息，具体代码如下

using System;
using System.Collections.Generic;
using System.Linq;using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using XRpgLibrary;
using XRpgLibrary.Controls;
namespace EyesOfTheDragon.GameScreens
{
public class CharacterGeneratorScreen : BaseGameState
 {
 #region Field Region
 LeftRightSelector genderSelector;//关于角色性别的selector控件
 LeftRightSelector classSelector;//关于角色类型的selector控件
 PictureBox backgroundImage;//游戏背景图片框
string[] genderItems = { "Male", "Female" };//用于初始化性别selector控件的字符串集
string[] classItems = { "Fighter", "Wizard", "Rogue", "Priest" };
 #endregion
 #region Property Region
 #endregion
 #region Constructor Region
public CharacterGeneratorScreen(Game game, GameStateManager stateManager)
 : base(game, stateManager)
 {
 }
 #endregion
 #region XNA Method Region
public override void Initialize()
 {
base.Initialize();
 }
protected override void LoadContent()
 {
 base.LoadContent();
 CreateControls();
 }
public override void Update(GameTime gameTime)
 {
 ControlManager.Update(gameTime, PlayerIndex.One);//对ControlManager进行更新，在其中会触发对页面上所有控件的更新
 base.Update(gameTime);
 }
public override void Draw(GameTime gameTime)
 {
 GameRef.SpriteBatch.Begin();
 base.Draw(gameTime);
 ControlManager.Draw(GameRef.SpriteBatch);//ControlManager的绘制，在其中可以对页面上所有控件进行绘制
 GameRef.SpriteBatch.End();
 }
 #endregion
 #region Method Region
private void CreateControls()
 {
Texture2D leftTexture = Game.Content.Load<Texture2D>(@"GUI\leftarrowUp");
Texture2D rightTexture = Game.Content.Load<Texture2D>(@"GUI\rightarrowUp");
Texture2D stopTexture = Game.Content.Load<Texture2D>(@"GUI\StopBar");
 backgroundImage = new PictureBox(
 Game.Content.Load<Texture2D>(@"Backgrounds\titlescreen"),
 GameRef.ScreenRectangle);
 ControlManager.Add(backgroundImage);//实例化背景控件，并加入到控件管理类中
 Label label1 = new Label();
 label1.Text = "Who will search for the Eyes of the Dragon?";
 label1.Size = label1.SpriteFont.MeasureString(label1.Text);
 label1.Position = new Vector2((GameRef.Window.ClientBounds.Width - label1.Size.X) /
2, 150);
 ControlManager.Add(label1);//实例化标题label，并加入到控件管理类中
 genderSelector = new LeftRightSelector(leftTexture, rightTexture, stopTexture);
 genderSelector.SetItems(genderItems, 125);
 genderSelector.Position = new Vector2(label1.Position.X, 200);
 ControlManager.Add(genderSelector);//实例化性别selector，加入管理类
 classSelector = new LeftRightSelector(leftTexture, rightTexture, stopTexture);
 classSelector.SetItems(classItems, 125);
 classSelector.Position = new Vector2(label1.Position.X, 250);
 ControlManager.Add(classSelector);//实例化类型selector，加入管理类
LinkLabel linkLabel1 = new LinkLabel();
 linkLabel1.Text = "Accept this character.";
 linkLabel1.Position = new Vector2(label1.Position.X, 300);
 linkLabel1.Selected += new EventHandler(linkLabel1_Selected);
 ControlManager.Add(linkLabel1);//实例化接受LinkLabel对象，加入管理类
 ControlManager.NextControl();//执行NextControl，使得当前呈现选项为被选中状态
 }
void linkLabel1_Selected(object sender, EventArgs e)
 {
 InputHandler.Flush();
 StateManager.PopState();
 StateManager.PushState(GameRef.GamePlayScreen);//呈现游戏页面
 }
 #endregion
 }
}

接下来就是讲新的角色选择页面添加到Game1类中，代码如下

public CharacterGeneratorScreen CharacterGeneratorScreen;
public Game1()
{
 graphics = new GraphicsDeviceManager(this);
 graphics.PreferredBackBufferWidth = screenWidth;
 graphics.PreferredBackBufferHeight = screenHeight;
 ScreenRectangle = new Rectangle(
 0,
 0,
 screenWidth,
 screenHeight);
 Content.RootDirectory = "Content";
 Components.Add(new InputHandler(this)); 
 stateManager = new GameStateManager(this);
 Components.Add(stateManager);
 TitleScreen = new TitleScreen(this, stateManager);
 StartMenuScreen = new StartMenuScreen(this, stateManager);
 GamePlayScreen = new GamePlayScreen(this, stateManager);
 CharacterGeneratorScreen = new CharacterGeneratorScreen(this, stateManager);//添加新的页面
 stateManager.ChangeState(TitleScreen);
}

同时在StartMenuScreen页面中修改menuItem_Selected方法，使得选择startgame选项时候，跳转到新建的角色选择页面

private void menuItem_Selected(object sender, EventArgs e)
{
if (sender == startGame)
 {
 StateManager.PushState(GameRef.CharacterGeneratorScreen);
 }
if (sender == loadGame)
 {
 StateManager.PushState(GameRef.GamePlayScreen);
 }
if (sender == exitGame)
 {
 GameRef.Exit();
 }
}

OK,本节任务结束