ArcTest.java

/*
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 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */



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


/**
 * An interactive test of the Graphics.drawArc and Graphics.fillArc
 * routines. Can be run either as a standalone application by
 * typing "java ArcTest" or as an applet in the AppletViewer.
 */
@SuppressWarnings("serial")
public class ArcTest extends Applet {

    ArcControls controls;   // The controls for marking and filling arcs
    ArcCanvas canvas;       // The drawing area to display arcs

    @Override
    public void init() {
        setLayout(new BorderLayout());
        canvas = new ArcCanvas();
        add("Center", canvas);
        add("South", controls = new ArcControls(canvas));
    }

    @Override
    public void destroy() {
        remove(controls);
        remove(canvas);
    }

    @Override
    public void start() {
        controls.setEnabled(true);
    }

    @Override
    public void stop() {
        controls.setEnabled(false);
    }

    @Override
    public void processEvent(AWTEvent e) {
        if (e.getID() == Event.WINDOW_DESTROY) {
            System.exit(0);
        }
    }

    public static void main(String args[]) {
        Frame f = new Frame("ArcTest");
        ArcTest arcTest = new ArcTest();

        arcTest.init();
        arcTest.start();

        f.add("Center", arcTest);
        f.setSize(300, 300);
        f.setVisible(true);
    }

    @Override
    public String getAppletInfo() {
        return "An interactive test of the Graphics.drawArc and \nGraphics."
                + "fillArc routines. Can be run \neither as a standalone "
                + "application by typing 'java ArcTest' \nor as an applet in "
                + "the AppletViewer.";
    }
}


@SuppressWarnings("serial")
class ArcCanvas extends Canvas {

    int startAngle = 0;
    int extent = 45;
    boolean filled = false;
    Font font = new java.awt.Font("SansSerif", Font.PLAIN, 12);

    @Override
    public void paint(Graphics g) {
        Rectangle r = getBounds();
        int hlines = r.height / 10;
        int vlines = r.width / 10;

        g.setColor(Color.pink);
        for (int i = 1; i <= hlines; i++) {
            g.drawLine(0, i * 10, r.width, i * 10);
        }
        for (int i = 1; i <= vlines; i++) {
            g.drawLine(i * 10, 0, i * 10, r.height);
        }

        g.setColor(Color.red);
        if (filled) {
            g.fillArc(0, 0, r.width - 1, r.height - 1, startAngle, extent);
        } else {
            g.drawArc(0, 0, r.width - 1, r.height - 1, startAngle, extent);
        }

        g.setColor(Color.black);
        g.setFont(font);
        g.drawLine(0, r.height / 2, r.width, r.height / 2);
        g.drawLine(r.width / 2, 0, r.width / 2, r.height);
        g.drawLine(0, 0, r.width, r.height);
        g.drawLine(r.width, 0, 0, r.height);
        int sx = 10;
        int sy = r.height - 28;
        g.drawString("Start = " + startAngle, sx, sy);
        g.drawString("Extent = " + extent, sx, sy + 14);
    }

    public void redraw(boolean filled, int start, int extent) {
        this.filled = filled;
        this.startAngle = start;
        this.extent = extent;
        repaint();
    }
}


@SuppressWarnings("serial")
class ArcControls extends Panel
        implements ActionListener {

    TextField startTF;
    TextField extentTF;
    ArcCanvas canvas;

    @SuppressWarnings("LeakingThisInConstructor")
    public ArcControls(ArcCanvas canvas) {
        Button b = null;

        this.canvas = canvas;
        add(startTF = new IntegerTextField("0", 4));
        add(extentTF = new IntegerTextField("45", 4));
        b = new Button("Fill");
        b.addActionListener(this);
        add(b);
        b = new Button("Draw");
        b.addActionListener(this);
        add(b);
    }

    @Override
    public void actionPerformed(ActionEvent ev) {
        String label = ev.getActionCommand();

        int start, extent;
        try {
            start = Integer.parseInt(startTF.getText().trim());
        } catch (NumberFormatException ignored) {
            start = 0;
        }
        try {
            extent = Integer.parseInt(extentTF.getText().trim());
        } catch (NumberFormatException ignored) {
            extent = 0;
        }

        canvas.redraw(label.equals("Fill"), start, extent);
    }
}


@SuppressWarnings("serial")
class IntegerTextField extends TextField {

    String oldText = null;

    public IntegerTextField(String text, int columns) {
        super(text, columns);
        enableEvents(AWTEvent.KEY_EVENT_MASK | AWTEvent.TEXT_EVENT_MASK);
        oldText = getText();
    }

    // Consume non-digit KeyTyped events
    // Note that processTextEvent kind of eliminates the need for this
    // function, but this is neater, since ideally, it would prevent
    // the text from appearing at all.  Sigh.  See bugid 4100317/4114565.
    //
    @Override
    protected void processEvent(AWTEvent evt) {
        int id = evt.getID();
        if (id != KeyEvent.KEY_TYPED) {
            super.processEvent(evt);
            return;
        }

        KeyEvent kevt = (KeyEvent) evt;
        char c = kevt.getKeyChar();

        // Digits, backspace, and delete are okay
        // Note that the minus sign is allowed, but not the decimal
        if (Character.isDigit(c) || (c == '\b') || (c == '\u007f') || (c
                == '\u002d')) {
            super.processEvent(evt);
            return;
        }

        Toolkit.getDefaultToolkit().beep();
        kevt.consume();
    }

    // Should consume TextEvents for non-integer Strings
    // Store away the text in the tf for every TextEvent
    // so we can revert to it on a TextEvent (paste, or
    // legal key in the wrong location) with bad text
    //
    @Override
    protected void processTextEvent(TextEvent te) {
        // The empty string is okay, too
        String newText = getText();
        if (newText.equals("") || textIsInteger(newText)) {
            oldText = newText;
            super.processTextEvent(te);
            return;
        }

        Toolkit.getDefaultToolkit().beep();
        setText(oldText);
    }

    // Returns true for Integers (zero and negative
    // values are allowed).
    // Note that the empty string is not allowed.
    //
    private boolean textIsInteger(String textToCheck) {

        try {
            Integer.parseInt(textToCheck, 10);
            return true;
        } catch (NumberFormatException ignored) {
            return false;
        }
    }
}