flagmakergui.java

Java经典例程 从外国一大学计算机教授出版物下载的代码 经典

import java.awt.*;
import java.awt.event.*;

public class FlagMakerGUI extends Frame
                          implements ActionListener, ItemListener  {

  /** General Flag designer program       J M Bishop May 2000
   *  =====================
   *
   *  Presents a simple GUI for selecting one of
   * three styles of flag, plus three motifs and
   * seven colours for each bar or stripe.
   *
   * Illustrates inherited classes and GUI components
   * particularly Choices, Checkboxes and Buttons.
   *
   **/

  static final int none = 0, circle = 1,  star = 2, starOfDavid = 3;
  static final int stripes = 0, bars = 1, motif = 2;
  static final Color listedColours [] = {Color.red, Color.blue, Color.white,
                     Color.black, Color.green, Color.orange, Color.yellow};

  // GUI variables
  // *************

  CheckboxGroup flagParts;
  Checkbox []   colourCheck = new Checkbox[4];
  Choice        colourChoice;
  Choice        flagChoice;
  Choice        motifChoice;
  TextField     nameField;
  Button        drawButton;

  public FlagMakerGUI() {

  // Laying out the GUI
  // ******************

    setLayout(new BorderLayout());
    Panel intro = new Panel();
      intro.add(new Label("Design a Flag"));
      add("North",intro);
    Panel middle = new Panel();
      middle.setLayout(new FlowLayout());
        flagParts = new CheckboxGroup();
          for (int i=0; i<3; i++)
            colourCheck[i] = new Checkbox("Colour "+(i+1),i==1,flagParts);
          colourCheck[3] = new Checkbox("Motif colour",false,flagParts);
          for (int i=0; i<4; i++) {
            colourCheck[i].addItemListener(this);
            middle.add(colourCheck[i]);
          }
        colourChoice = new Choice ();
          colourChoice.addItem("Red");
          colourChoice.addItem("Blue");
          colourChoice.addItem("White");
          colourChoice.addItem("Black");
          colourChoice.addItem("Green");
          colourChoice.addItem("Orange");
          colourChoice.addItem("Yellow");
          colourChoice.addItemListener(this);
          middle.add(colourChoice);
        flagChoice = new Choice ();
          flagChoice.addItem("Striped");
          flagChoice.addItem("Bars");
          flagChoice.addItem("Striped with motif");
          flagChoice.addItemListener(this);
          middle.add(flagChoice);
        motifChoice = new Choice();
          motifChoice.addItem("none");
          motifChoice.addItem("Circle");
          motifChoice.addItem("Star");
          motifChoice.addItem("Star Of David");
          motifChoice.addItemListener(this);
          middle.add(motifChoice);
        nameField = new TextField("    A Flag      ",20);
          nameField.addActionListener(this);
          middle.add(nameField);
        drawButton = new Button("Draw it");
          drawButton.addActionListener(this);
          middle.add(drawButton);
      add("Center",middle);
    setTitle("Flag Designer");
    setSize(250,200);
    //pack();
    setVisible(true);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
  }

  // Variables for the event handlers
  int       flagPicked = 0;
  int       checkBoxPicked = 0; // colour 1
  int       motifPicked = circle;
  Color [ ] colour = {Color.red, Color.white, Color.blue, Color.black};
  String    name = "A Flag";

  public void actionPerformed (ActionEvent e) {
    if (e.getSource() == drawButton) {
      switch (flagPicked) {
        case stripes : makeFlag (
             new FlagCanvas (name, colour[0], colour[1], colour[2]));
             break;
        case bars : makeFlag (
             new FlagCanvasVerti (name, colour[0], colour[1], colour[2]));
             break;
        case motif : makeFlag (
             new FlagCanvasMotif (name, colour[0], colour[1], colour[2],
             motifPicked, colour[3]));
      }}
    else if (e.getSource() == nameField)
      name = nameField.getText();
  }

  public void itemStateChanged(ItemEvent e) {
    Object picked = e.getSource();

    // Distinguish between the four components
    // Colour choice
    if (picked == colourChoice) {
      int selectedColour = ((Choice) picked).getSelectedIndex();
      colour[checkBoxPicked] = listedColours[selectedColour];
    }
    // Flag choice
    else if (picked == flagChoice)
      flagPicked = ((Choice) picked).getSelectedIndex();
    // Motif choice
    else if (picked == motifChoice)
      motifPicked = ((Choice) picked).getSelectedIndex();
    else
    // Check boxes (by default)
    for (int i=0; i<4; i++) {
      if (picked == colourCheck[i]) {
        checkBoxPicked = i;
      }
    }

  }

   public static void main(String [] args) {
     new FlagMakerGUI();
  }

  public static void makeFlag (FlagCanvas canvas) {
    Frame f = new Frame();
    f.add(canvas);
    f.setTitle(canvas.country);
    f.setSize(300,250);
    f.setLocation(200,200);
    f.setVisible(true);
    f.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        e.getWindow().dispose();
      }
    });
  }
}

//===========================
  class FlagCanvas extends Canvas {

    String country;
    Color bar1, bar2, bar3;

     FlagCanvas (String c, Color b1, Color b2, Color b3) {
       country = c;
       bar1 = b1;
       bar2 = b2;
       bar3 = b3;
     }

     public void paint (Graphics g) {
      // Draw the flag from coloured rectangles
      g.setColor (bar1);
      g.fillRect (40,40,200,40);
      g.setColor (bar2);
      g.fillRect (40,80,200,40);
      g.setColor (bar3);
      g.fillRect (40,120,200,40);
      // Label the drawing
      g.setColor (Color.black);
      g.drawString(country,100,180);
    }
  }

  class FlagCanvasVerti extends FlagCanvas {

    FlagCanvasVerti (String c, Color b1, Color b2, Color b3) {
      super (c,b1,b2,b3);
    }

    public void paint (Graphics g) {
      // Draw the flag from coloured rectangles
      g.setColor (bar1);
      g.fillRect (40,40,60,120);
      g.setColor (bar2);
      g.fillRect (100,40,60,120);
      g.setColor (bar3);
      g.fillRect (160,40,60,120);
      // Label the drawing
      g.setColor (Color.black);
      g.drawString(country,100,180);
    }
   }


  class FlagCanvasMotif extends FlagCanvas {

    int motif;
    Color motifColor;

    FlagCanvasMotif (String c, Color b1, Color b2, Color b3, int m, Color mc) {
      super (c,b1,b2,b3);
      motif = m;
      motifColor = mc;
    }

    public void paint (Graphics g) {

      int [] xpoints = {120,150,122,135,142,120};
      int [] ypoints = {90,90,115,80,115,90};
      // Draw the flag from coloured rectangles
      g.setColor (bar1);
      g.fillRect (40,40,200,40);
      g.setColor (bar2);
      g.fillRect (40,80,200,40);
      g.setColor (bar3);
      g.fillRect (40,120,200,40);
      // Label the drawing
      g.setColor (Color.black);
      g.drawString(country,100,180);
      if (motif != 0) {
        g.setColor (motifColor);
        switch (motif) {
        case 1: g.fillOval(125,90,20,20); break;
        case 2: g.fillPolygon(xpoints,ypoints,6); break;
        case 3: g.drawPolygon(xpoints,ypoints,6); break;
        default: break;
        }
      }
    }
  }