mainpanel.java

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package system;

import java.awt.*;
import javax.swing.*;

import snake.*;
import food.*;

//============================================================================
//                    此面板现在的宽度和高度都是501像素
//============================================================================
public class MainPanel
    extends JPanel {
  private MainFrame mainFrame;
  private Image backGround; //背景图片
  private Image offScreen; //次画面，用来防止图象的闪烁
  private Graphics g2; //次画面的Graphics对象

  //背景图片的宽度和高度
  public static final int IMAGE_WIDTH = 20;
  public static final int IMAGE_HEIGHT = 20;

  public MainPanel(MainFrame frame) {
    this.mainFrame = frame;
    this.setBackground(Color.yellow);
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    //获得面板的高度和宽度
    int width = this.getWidth();
    int height = this.getHeight();

    //取得地板的图片
    this.backGround = new ImageIcon(Config.CURRENT_BG).getImage();

    //建立次画面，处理图象的闪烁
    this.offScreen = this.createImage(this.getWidth(), this.getHeight());
    this.g2 = this.offScreen.getGraphics();

   //======================以平铺的方式绘制地板===============================
    int iX = (int) width / MainPanel.IMAGE_WIDTH;
    int iY = (int) height / MainPanel.IMAGE_HEIGHT;
    for (int i = 0; i <= iX; i++) {
      for (int j = 0; j <= iY; j++) {
        this.g2.drawImage(this.backGround, MainPanel.IMAGE_WIDTH * i,
        		MainPanel.IMAGE_HEIGHT * j,
        		MainPanel.IMAGE_WIDTH, MainPanel.IMAGE_HEIGHT, this);
      }
    }

    //====================贪吃蛇死亡，绘制Game Over字符=======================
    if (this.mainFrame.isGameOver()) {
      Font oldFont = this.g2.getFont(); //保存原有字体
      Color oldColor = this.g2.getColor(); //保存原有颜色

      this.g2.setFont(new Font("Dialog", Font.BOLD, 64));
      //取得GAME OVER字符的相关信息
      FontMetrics fm = this.g2.getFontMetrics();
      int ascent = fm.getAscent(); //上坡度
      int descent = fm.getDescent(); //下坡度
      int length = fm.stringWidth(Config.GAME_OVER);

      //计算字符串绘制的位置（在面板的中央）
      int x = (width - length) / 2;
      int y = (height - (ascent + descent)) / 2 + ascent;

      //设置新的颜色
      this.g2.setColor(new Color(0, 0, 0, 128));
      //绘制字符
      this.g2.drawString(Config.GAME_OVER, x, y);
      this.g2.setColor(new Color(255, 50, 50, 200));
      this.g2.drawString(Config.GAME_OVER, x - 4, y - 4);

      //恢复原有的字体和颜色
      this.g2.setFont(oldFont);
      this.g2.setColor(oldColor);
    }
    else if(this.mainFrame.isWelcome()){
      //========================显示开头画面=============================
      Font oldFont = this.g2.getFont(); //保存原有字体
        Color oldColor = this.g2.getColor(); //保存原有颜色

        //设置新的字体和颜色
        this.g2.setFont(new Font("Dialog", Font.BOLD, 96));
        this.g2.setColor(new Color(0, 0, 0, 200));

        //取得GO字符的相关信息
        FontMetrics fm = this.g2.getFontMetrics();
        int ascent = fm.getAscent(); //上坡度
        int descent = fm.getDescent(); //下坡度
        int length = fm.stringWidth(Config.GAME_NAME);

        //计算字符串绘制的位置（在面板的中央）
        int x = (width - length) / 2;
        int y = (height - (ascent + descent)) / 2;

        //绘制“贪吃蛇”字符
        this.g2.drawString(Config.GAME_NAME, x, y);
        this.g2.setColor(new Color(12, 244, 12, 255));
        this.g2.drawString(Config.GAME_NAME, x + 8, y + 8);

        //绘制版本号
        this.g2.setFont(new Font("Dialog", Font.PLAIN, 12));
        fm = this.g2.getFontMetrics();
        length = fm.stringWidth(Config.VERSION);
        x = (width - length) / 2;
        y += descent + 30;//在“贪吃蛇”下面10象素处绘制
        this.g2.setColor(Color.black);
        this.g2.drawString(Config.VERSION,x,y);

        //绘制“华游工作室”
        this.g2.setFont(new Font("Dialog", Font.BOLD, 32));
        fm = this.g2.getFontMetrics();
        length = fm.stringWidth("华游工作室");
        x = (width - length) / 2;
        y += 80;//在版本号下面30象素处绘制
        this.g2.setColor(new Color(0,0,0,200));
        this.g2.drawString("华游工作室",x,y);
        this.g2.setColor(Color.red);
        this.g2.drawString("华游工作室",x + 2,y + 2);

        //恢复原有的字体和颜色
        this.g2.setFont(oldFont);
        this.g2.setColor(oldColor);
    }
    else {
      //======================在开始新游戏时，绘制GO字符串=================
      if (this.mainFrame.isNewGame()) {
        Font oldFont = this.g2.getFont(); //保存原有字体
        Color oldColor = this.g2.getColor(); //保存原有颜色

        //设置新的字体和颜色
        this.g2.setFont(new Font("Dialog", Font.BOLD + Font.ITALIC, 64));
        this.g2.setColor(new Color(0, 0, 0, 200));

        //取得GO字符的相关信息
        FontMetrics fm = this.g2.getFontMetrics();
        int ascent = fm.getAscent(); //上坡度
        int descent = fm.getDescent(); //下坡度
        int length = fm.stringWidth("G O！！！");

        //计算字符串绘制的位置（在面板的中央）
        int x = (width - length) / 2;
        int y = (height - (ascent + descent)) / 2 + ascent;

        //绘制字符
        this.g2.drawString("G O！！！", x, y);
        this.g2.setColor(new Color(255,0,0,200));
        this.g2.drawString("G O！！！", x - 2, y - 2);

        //恢复原有的字体和颜色
        this.g2.setFont(oldFont);
        this.g2.setColor(oldColor);

        //设置isNewGame为false，表示字符绘制完毕
//        this.mainFrame.setNewGame(false);
      }

      if(this.mainFrame.isLevelUp()){
        Font oldFont = this.g2.getFont(); //保存原有字体
        Color oldColor = this.g2.getColor(); //保存原有颜色

        //设置新的字体和颜色
        this.g2.setFont(new Font("Dialog", Font.BOLD + Font.ITALIC, 64));
        this.g2.setColor(new Color(0, 0, 0, 200));

        //取得GO字符的相关信息
        FontMetrics fm = this.g2.getFontMetrics();
        int ascent = fm.getAscent(); //上坡度
        int descent = fm.getDescent(); //下坡度
        int length = fm.stringWidth("Level Up！");

        //计算字符串绘制的位置（在面板的中央）
        int x = (width - length) / 2;
        int y = (height - (ascent + descent)) / 2 + ascent;

        //绘制字符
        this.g2.drawString("Level Up！", x, y);
        this.g2.setColor(new Color(20,200,20,200));
        this.g2.drawString("Level Up！", x - 2, y - 2);

        //恢复原有的字体和颜色
        this.g2.setFont(oldFont);
        this.g2.setColor(oldColor);

        //设置isLevelUp为false，表示字符绘制完毕
//        this.mainFrame.setLevelUp(false);
      }

      //=============================显示贪吃蛇===========================
      Snake s = this.mainFrame.getSnake();
      if (s == null || s.size() < 1) {
        return;
      }

      for (int i = 0; i < s.size(); i++) {
        Block b = (Block) s.get(i);
        this.g2.drawImage(b.getImage(), b.getX(), b.getY(), Block.WIDTH, Block.HEIGHT, this);
      }

      //===========================显示食物==============================
      Food f = this.mainFrame.getFood();
      this.g2.drawImage(f.getImage(), f.getX(), f.getY(), Food.WIDTH, Food.HEIGHT, this);
    }

    //============================将次画面画到屏幕上======================
    g.drawImage(this.offScreen, 0, 0, this);
  }
} //:~zj