Java基础之在窗口中绘图——绘制星星（StarApplet 1）

时间：2022-11-02 03:13:55

Applet程序。

可以把更复杂的几何形状定义为GeneralPath类型的对象。GeneralPath可以是直线、Quad2D曲线和Cubic2D曲线的结合体，甚至可以包含其他GeneralPath对象。

1、绘制星星：

 import java.awt.geom.*;

 public class Star {

   // Return a path for a star at x,y

   public static GeneralPath starAt(float x, float y) {

     Point2D.Float point = new Point2D.Float(x, y);

     p = new GeneralPath(GeneralPath.WIND_NON_ZERO);

     p.moveTo(point.x, point.y);

     p.lineTo(point.x + 20.0f, point.y - 5.0f);                         // Line from start to A

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x + 5.0f, point.y - 20.0f);                         // Line from A to B

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x + 5.0f, point.y + 20.0f);                         // Line from B to C

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x + 20.0f, point.y + 5.0f);                         // Line from C to D

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x - 20.0f, point.y + 5.0f);                         // Line from D to E

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x - 5.0f, point.y + 20.0f);                         // Line from E to F

     point = (Point2D.Float)p.getCurrentPoint();

     p.lineTo(point.x - 5.0f, point.y - 20.0f);                         // Line from F to g

     p.closePath();                                                     // Line from G to start

     return p;                                                          // Return the path

   }

   private static GeneralPath p;                                        // Star path

 }

2、定义用来绘制星星的Applet:

 import javax.swing.*;

 import java.awt.*;

 @SuppressWarnings("serial")

 public class StarApplet extends JApplet {

   // Initialize the applet

   @Override

   public void init() {

     StarPane pane = new StarPane();                                    // Pane containing stars

     getContentPane().add(pane);                                        // BorderLayout.CENTER is default position

   }

   // Class defining a pane on which to draw

   class StarPane extends JComponent {

     @Override

     public void paint(Graphics g) {

       Graphics2D g2D = (Graphics2D)g;

       float delta = 60f;                                               // Increment between stars

       float starty = 0f;                                               // Starting y position

       // Draw 3 rows of stars

       for(int yCount = 0 ; yCount < 3 ; yCount++) {

         starty += delta;                                               // Increment row position

         float startx = 0f;                                             // Start x position in a row

         // Draw a row of 4 stars

         for(int xCount = 0 ; xCount < 4 ; xCount++) {

           g2D.draw(Star.starAt(startx += delta, starty));

         }

       }

     }

   }

 }

3、HTML文件:

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

 <html>     <head>  </head>

     <body bgcolor="000000">

         <center>

             <applet

                 code    = "StarApplet.class"

                 width    = "360"

                 height    = "240"

                 >

             </applet>

         </center>

     </body>

 </html>

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