fontselection.java

初期JAVA学习非常有用的资料。帮助深入了解API。特别是Applet。

/*
* @(#)FontSelection.java   1.2 98/07/31
*/


import java.lang.Integer;
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Vector;

/*
 * This applet displays a String with the user's selected 
 * fontname, style and size attributes.
*/

public class FontSelection extends JApplet implements ItemListener {
    JLabel fontLabel, sizeLabel, styleLabel;
    FontPanel fontC;
    JComboBox fonts, sizes, styles;
    int index = 0;
    String fontchoice = "fontchoice";
    int stChoice = 0;
    String siChoice = "10";

    public void init() {

        getContentPane().setLayout( new BorderLayout() );

        JPanel topPanel = new JPanel();
        JPanel fontPanel = new JPanel();
        JPanel sizePanel = new JPanel();
        JPanel stylePanel = new JPanel();
        JPanel sizeAndStylePanel = new JPanel();

        topPanel.setLayout( new BorderLayout() );
        fontPanel.setLayout( new GridLayout( 2, 1 ) );
        sizePanel.setLayout( new GridLayout( 2, 1 ) );
        stylePanel.setLayout( new GridLayout( 2, 1 ) );
        sizeAndStylePanel.setLayout( new BorderLayout() );

        topPanel.add( BorderLayout.WEST, fontPanel );
        sizeAndStylePanel.add( BorderLayout.WEST, sizePanel );
        sizeAndStylePanel.add( BorderLayout.CENTER, stylePanel );
        topPanel.add( BorderLayout.CENTER, sizeAndStylePanel );

        getContentPane().add( BorderLayout.NORTH, topPanel );

        fontLabel = new JLabel();
        fontLabel.setText("Fonts");
        Font newFont = getFont().deriveFont(1);
        fontLabel.setFont(newFont);
        fontLabel.setHorizontalAlignment(JLabel.CENTER);
        fontPanel.add(fontLabel);

        sizeLabel = new JLabel();
        sizeLabel.setText("Sizes");
        sizeLabel.setFont(newFont);
        sizeLabel.setHorizontalAlignment(JLabel.CENTER);
        sizePanel.add(sizeLabel);

        styleLabel = new JLabel();
        styleLabel.setText("Styles");
        styleLabel.setFont(newFont);
        styleLabel.setHorizontalAlignment(JLabel.CENTER);
        stylePanel.add(styleLabel);

        GraphicsEnvironment gEnv = GraphicsEnvironment.getLocalGraphicsEnvironment();
        String envfonts[] = gEnv.getAvailableFontFamilyNames();
        Vector vector = new Vector();
        for ( int i = 1; i < envfonts.length; i++ ) {
            vector.addElement(envfonts[i]);
        }
        fonts = new JComboBox( vector );
        fonts.setMaximumRowCount( 9 );
        fonts.addItemListener(this);
        fontchoice = envfonts[0];
        fontPanel.add(fonts);

        sizes = new JComboBox( new Object[]{ "10", "12", "14", "16", "18"} );
        sizes.setMaximumRowCount( 9 );
        sizes.addItemListener(this);
        sizePanel.add(sizes);

        styles = new JComboBox( new Object[]{
                                "PLAIN",
                                "BOLD",
                                "ITALIC",
                                "BOLD & ITALIC"} );
        styles.setMaximumRowCount( 9 );
        styles.addItemListener(this);
        sizes.setMaximumRowCount( 9 );
        stylePanel.add(styles);

        fontC = new FontPanel();
        fontC.setBackground(Color.white);
        getContentPane().add( BorderLayout.CENTER, fontC);
    }

/*
 * Detects a state change in any of the Lists.  Resets the variable corresponding
 * to the selected item in a particular List.  Invokes changeFont with the currently
 * selected fontname, style and size attributes.
*/
    public void itemStateChanged(ItemEvent e) {
        if ( e.getStateChange() != ItemEvent.SELECTED ) {
            return;
        }

        Object list = e.getSource();

        if ( list == fonts ) {
            fontchoice = (String)fonts.getSelectedItem();
        } else if ( list == styles ) {
            index = styles.getSelectedIndex();
            stChoice = index;
        } else {
            siChoice = (String)sizes.getSelectedItem();
        }
        fontC.changeFont(fontchoice, stChoice, siChoice);
    }

    public static void main(String s[]) {
        JFrame f = new JFrame("FontSelection");
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });
        JApplet fontSelection = new FontSelection();
        f.getContentPane().add(fontSelection, BorderLayout.CENTER);
        fontSelection.init();
        f.setSize(new Dimension(550,250));
        f.setVisible(true);
    }

}


class FontPanel extends JPanel {

    Font thisFont;

    public FontPanel(){ 
        thisFont = new Font("Arial", Font.PLAIN, 10);
    }

    // Resets thisFont to the currently selected fontname, size and style attributes.
    public void changeFont(String f, int st, String si){
        Integer newSize = new Integer(si);
        int size = newSize.intValue();
        thisFont = new Font(f, st, size);
        repaint();
    }

    public void paintComponent (Graphics g) {
        super.paintComponent( g );
        Graphics2D g2 = (Graphics2D) g;
        int w = getWidth();
        int h = getHeight();

        g2.setColor(Color.darkGray);
        g2.setFont(thisFont);
        String change = "Pick a font, size, and style to change me";
        FontMetrics metrics = g2.getFontMetrics();
        int width = metrics.stringWidth( change );
        int height = metrics.getHeight();
        g2.drawString( change, w/2-width/2, h/2-height/2 );
    }
}