compositetest.java

来自「java learn PPT java learn PPT java learn」· Java 代码 · 共 171 行

     import java.applet.*;
     import java.awt.*;
     import java.awt.geom.*; 
     import java.util.*;

     // 封装方形的属性 (位置, 大小等）让它可以有规律的更新
     //  的一个简单方法
     class AlphaBox 
     {
          // 随机数生成器
          private static Random random = null;

          // 所有的绘制都将从一个单位正方形开始
          private static Rectangle2D square = null;

          // 恒等变换
          private static AffineTransform identity = null;

          // 盒子的属性
          private AlphaComposite alpha;               
          private double xPos;           // x, y 位置
          private double yPos;
          private double xVel;           // x, y 速度
          private double yVel;
          private double size;           // 宽和高
          private Color  color;          // 实例的颜色
          private Dimension windowSize;

          public AlphaBox(Dimension d)
          {
               windowSize = d;

               // 定义所有的空对象
               if(random == null)
               { 
                    random = new Random();
               }
       
               if(square == null)
               { 
                    square = new Rectangle2D.Float(-0.5f, -0.5f, 1.0f, 1.0f);
               }
              
               if(identity == null)
               {
                    identity = new AffineTransform();
               }

               // 所有的合成都将是 SRC_OVER 的而且透明
               // 使用这些值的随机数来得到一些很酷的效果
                    alpha = AlphaComposite.getInstance(
                    AlphaComposite.SRC_OVER, 0.25f);

               // 随机得到盒子的属性
               xPos = windowSize.width*random.nextDouble();
               yPos = windowSize.height*random.nextDouble();
               xVel = 1+2*random.nextDouble();
               if(random.nextDouble() > 0.5) xVel = -xVel;
               yVel = 1+2*random.nextDouble();
               if(random.nextDouble() > 0.5) yVel = -yVel;
               size = 25+100*random.nextDouble();
               color = new Color(random.nextInt()).brighter();
          }  

          // 根据盒子当前的属性把它绘制到所传入的 Graphics2D容器中
          public void paint(Graphics2D g2d)
          {
               // 让盒子在窗体上弹跳

               xPos += xVel;
               if(xPos > windowSize.width)
               {  
                    xPos = windowSize.width;
                    xVel = -xVel;
               }
               if(xPos < 0)
               {
                    xPos = 0;
                    xVel = -xVel;
               }

               yPos += yVel;
               if(yPos > windowSize.height)
               { 
                    yPos = windowSize.height;
                    yVel = -yVel;
               }
               if(yPos < 0)
               {
                    yPos = 0;
                    yVel = -yVel;
               }

               // render the box  
               g2d.setTransform(identity);
               g2d.translate(xPos, yPos);
               g2d.scale(size, size);
               g2d.setComposite(alpha);
               g2d.setPaint(color);
               g2d.fill(square);
          }

     }    // AlphaBox              
                       
     public class CompositeTest extends Applet implements Runnable
     {  
          // 动画线程 -- 稍后我们会谈到 
          private volatile Thread animation;

          // AlphaBox 对象数组
          private AlphaBox[] boxes;

          public void init()
          {
               animation = new Thread(this);

               // 创建这些盒子
               final int n = 10;
               boxes = new AlphaBox[n];
               Dimension size = this.getSize();
               for(int i = 0; i < n; i++)
               {
                    boxes[i] = new AlphaBox(size);
               }
          }

          public void start()
          {
               animation.start();
          }

          public void stop()
          {
               animation = null;
          }

          // 覆盖 update 方法，让它不要清除窗体 
          public void update(Graphics g)
          {
               paint(g);
          }

          public void paint(Graphics g)
          {
               Graphics2D g2d = (Graphics2D)g;

               // 绘制每一个AlphaBox
               for(int i = 0; i < boxes.length; i++)
               {
                    boxes[i].paint(g2d);
               }
          }

          public void run()
          {
               // 稍后我们会提到这个内容!
               Thread t = Thread.currentThread();
               while (t == animation)
               {
                    try 
                    {
                         t.sleep(10);
                    }
                    catch (InterruptedException e)
                    {
                    }
                    repaint();
                }      
          }

     }    // CompositeTest