cycletest.java

来自「java learn PPT java learn PPT java learn」· Java 代码 · 共 80 行

     import java.applet.*;
     import java.awt.*;
     import java.awt.event.*;
     import java.awt.geom.*; 
          
     public class CycleTest extends Applet implements ItemListener
     {  
          // 要绘制的矩形 
          private Rectangle2D rect;
 
          // 包含两个点的直线，它将确定绘制的端点
          private Line2D line;

          // 选择循环类型的单选框
          private Checkbox cyclic;
          private Checkbox acyclic;

          public void init()
          {
               // 创建一个单位正方形
               rect = new Rectangle2D.Float(-0.5f, -0.5f, 1.0f, 1.0f);

               // 设置终点. 
               line = new Line2D.Float(-0.25f, 0.0f, 0.25f, 0.0f);

               setBackground(Color.ORANGE);

               // 创建选择渐变循环类型的单选框                
               CheckboxGroup cbg = new CheckboxGroup();
               setLayout(new BorderLayout());
               Panel p = new Panel();
               p.setBackground(Color.GREEN);
               cyclic = new Checkbox("cyclic", cbg, true);
               cyclic.addItemListener(this);
               p.add(cyclic);
               acyclic = new Checkbox("acyclic", cbg, false);        
               acyclic.addItemListener(this);
               p.add(acyclic);
               add(p, BorderLayout.SOUTH);
          }

          public void paint(Graphics g)
          {
               // 缩放后的矩形宽度
               final double scaleWidth = 100.0f;

               //  把传入的Graphics容器转换为一个可用的 Graphics2D 对象
               Graphics2D g2d = (Graphics2D)g;

               // 平移
               g2d.translate(100,100);
               g2d.scale(scaleWidth, 50);

               // 绘制              
               g2d.setPaint(new GradientPaint(
                    line.getP1(), Color.BLACK, line.getP2(), Color.WHITE, cyclic.getState()));
               g2d.fill(rect);

               // 画出端点处的垂线
               g2d.setPaint(Color.RED);

               g2d.setTransform(new AffineTransform());
               g2d.translate(100-0.25*scaleWidth, 100);
               g2d.rotate(Math.PI/2);
               g2d.scale(scaleWidth/2, 1);
               g2d.draw(line);

               g2d.setTransform(new AffineTransform());
               g2d.translate(100+0.25*scaleWidth, 100);
               g2d.rotate(Math.PI/2);
               g2d.scale(scaleWidth/2, 1);
               g2d.draw(line);
          }

          public void itemStateChanged(ItemEvent e)
          {
               // 更新!
               repaint();
          }
     }    // CycleTest