enemytanksprite.java

1) 图像的基本操作； 2) ImageObserver接口、ImageProducer接口的应用； 3) FilteredImageSource类、ImageFilter类、CropImageF

package tankgame611;
import java.applet.Applet;
import java.awt.Image;
import java.util.Random;

public class EnemyTankSprite extends SpriteDrawing{

  int AppletWidth, AppletHeight;
  int enemyTankWidth, enemyTankHeight;
  int direction;
  int enemyTankX, enemyTankY;
  Image enemyTankImg[];
  Applet GameApplet;
  Random rand;
  int TimeCount = 0;
  static int speed = 2;
  ShellSprite shell;

  public EnemyTankSprite(Image[] enemyTankImg,
                         int enemyTankX,
                         int enemyTankY,
                         ShellSprite shell,
                         Applet GameApplet) {
    super(enemyTankImg, enemyTankX, enemyTankY, GameApplet); //调用父类的创建方法
    this.enemyTankX = enemyTankX;
    this.enemyTankY = enemyTankY;
    this.enemyTankImg = enemyTankImg;
    this.shell = shell;
    this.GameApplet = GameApplet;
    AppletWidth = GameApplet.getWidth();
    AppletHeight = GameApplet.getHeight();

    setVisible(true);
    setActive(true);
    rand = new Random();

  }

  //direction : 0=左; 1=右; 2=上; 3=下;
  public void updateState(int SpiritDirection){
    enemyTankWidth = enemyTankImg[0].getWidth(GameApplet);
    enemyTankHeight = enemyTankImg[0].getHeight(GameApplet);
    //移动坦克
    switch (SpiritDirection) {
      case 0: //左
        if (enemyTankX <= 0){//设定坦克的左边界
          enemyTankX = 0;
          this.direction = 1;
        }
        else
          enemyTankX = this.getX() - speed;
        break;
      case 1: //右
        if (enemyTankX >= AppletWidth - enemyTankWidth){ //设定坦克的右边界
          enemyTankX = AppletWidth - enemyTankWidth;
          this.direction = 0;
        }
        else
          enemyTankX = this.getX() + speed;
        break;
      case 2: //上
        if (enemyTankY <= 0){//设定坦克的上边界
          enemyTankY = 0;
          this.direction = 3;
        }
        else
          enemyTankY = this.getY() - speed;
        break;
      case 3: //下
        if (enemyTankY >= AppletHeight - enemyTankHeight){//设定坦克的下边界
          enemyTankY = AppletHeight - enemyTankHeight;
          this.direction = 2;
        }
        else
          enemyTankY = this.getY() + speed;
        break;
    }
    //设定坦克图像的最新位置
    this.setPos(enemyTankX, enemyTankY);
    if(shell.visible == false && this.visible == true){
      shell.setShellDirection(SpiritDirection);
      setShellPos(SpiritDirection);
      shell.setVisible(true);
    }
  }

  public int getTankDirection() {
    return direction;
  }

  public void setTankDirection(int direction) {
    this.direction = direction;
  }

  //调整炮弹的位置
  public void setShellPos(int direction) {
    switch (direction) {
      case 0: //左
        shell.setPos(enemyTankX - shell.getWidth(),
                          enemyTankY + (enemyTankHeight - shell.getHeight()) / 2);
        break;
      case 1:
        shell.setPos(enemyTankX + enemyTankWidth + shell.getWidth(),
                          enemyTankY +
                          (enemyTankHeight - shell.getHeight()) / 2);
        break;
      case 2:
        shell.setPos(enemyTankX +
                          (enemyTankHeight - shell.getHeight()) / 2,
                          enemyTankY - enemyTankWidth / 2);
        break;
      case 3:
        shell.setPos(enemyTankX +
                          (enemyTankHeight - shell.getHeight()) / 2,
                          enemyTankY + enemyTankWidth);
        break;
    }
  }

}