EventTester.java Source code

Introduction

Here is the source code for EventTester.java

Source

//File: applet.html
/*
<applet code="EventTester.class"
   codebase="."
   width=400 height=400>
</applet>
    
    
*/
///
/*
 * Copyright (c) 2000 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 2nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book (recommended),
 * visit http://www.davidflanagan.com/javaexamples2.
 */

import java.applet.Applet;
import java.awt.Event;
import java.awt.Graphics;
import java.util.Vector;

/** An applet that gives details about Java 1.0 events */
public class EventTester extends Applet {
    // Handle mouse events
    public boolean mouseDown(Event e, int x, int y) {
        showLine(mods(e.modifiers) + "Mouse Down: [" + x + "," + y + "]");
        return true;
    }

    public boolean mouseUp(Event e, int x, int y) {
        showLine(mods(e.modifiers) + "Mouse Up: [" + x + "," + y + "]");
        return true;
    }

    public boolean mouseDrag(Event e, int x, int y) {
        showLine(mods(e.modifiers) + "Mouse Drag: [" + x + "," + y + "]");
        return true;
    }

    public boolean mouseMove(Event e, int x, int y) {
        showLine(mods(e.modifiers) + "Mouse Move: [" + x + "," + y + "]");
        return true;
    }

    public boolean mouseEnter(Event e, int x, int y) {
        showLine("Mouse Enter: [" + x + "," + y + "]");
        return true;
    }

    public boolean mouseExit(Event e, int x, int y) {
        showLine("Mouse Exit: [" + x + "," + y + "]");
        return true;
    }

    // Handle focus events
    public boolean gotFocus(Event e, Object what) {
        showLine("Got Focus");
        return true;
    }

    public boolean lostFocus(Event e, Object what) {
        showLine("Lost Focus");
        return true;
    }

    // Handle key down and key up events
    // This gets more confusing because there are two types of key events
    public boolean keyDown(Event e, int key) {
        int flags = e.modifiers;
        if (e.id == Event.KEY_PRESS) // a regular key
            showLine("Key Down: " + mods(flags) + key_name(e));
        else if (e.id == Event.KEY_ACTION) // a function key
            showLine("Function Key Down: " + mods(flags) + function_key_name(key));
        return true;
    }

    public boolean keyUp(Event e, int key) {
        int flags = e.modifiers;
        if (e.id == Event.KEY_RELEASE) // a regular key
            showLine("Key Up: " + mods(flags) + key_name(e));
        else if (e.id == Event.KEY_ACTION_RELEASE) // a function key
            showLine("Function Key Up: " + mods(flags) + function_key_name(key));
        return true;
    }

    // The remaining methods help us sort out the various modifiers and keys

    // Return the current list of modifier keys
    private String mods(int flags) {
        String s = "[ ";
        if (flags == 0)
            return "";
        if ((flags & Event.SHIFT_MASK) != 0)
            s += "Shift ";
        if ((flags & Event.CTRL_MASK) != 0)
            s += "Control ";
        if ((flags & Event.META_MASK) != 0)
            s += "Meta ";
        if ((flags & Event.ALT_MASK) != 0)
            s += "Alt ";
        s += "] ";
        return s;
    }

    // Return the name of a regular (non-function) key.
    private String key_name(Event e) {
        char c = (char) e.key;
        if (e.controlDown()) { // If CTRL flag is set, handle control chars.
            if (c < ' ') {
                c += '@';
                return "^" + c;
            }
        } else { // If CTRL flag is not set, then certain ASCII
            switch (c) { // control characters have special meaning.
            case '\n':
                return "Return";
            case '\t':
                return "Tab";
            case '\033':
                return "Escape";
            case '\010':
                return "Backspace";
            }
        }
        // Handle the remaining possibilities.
        if (c == '\177')
            return "Delete";
        else if (c == ' ')
            return "Space";
        else
            return String.valueOf(c);
    }

    // Return the name of a function key. Just compare the key to the
    // constants defined in the Event class.
    private String function_key_name(int key) {
        switch (key) {
        case Event.HOME:
            return "Home";
        case Event.END:
            return "End";
        case Event.PGUP:
            return "Page Up";
        case Event.PGDN:
            return "Page Down";
        case Event.UP:
            return "Up";
        case Event.DOWN:
            return "Down";
        case Event.LEFT:
            return "Left";
        case Event.RIGHT:
            return "Right";
        case Event.F1:
            return "F1";
        case Event.F2:
            return "F2";
        case Event.F3:
            return "F3";
        case Event.F4:
            return "F4";
        case Event.F5:
            return "F5";
        case Event.F6:
            return "F6";
        case Event.F7:
            return "F7";
        case Event.F8:
            return "F8";
        case Event.F9:
            return "F9";
        case Event.F10:
            return "F10";
        case Event.F11:
            return "F11";
        case Event.F12:
            return "F12";
        }
        return "Unknown Function Key";
    }

    /** A list of lines to display in the window */
    protected Vector lines = new Vector();

    /** Add a new line to the list of lines, and redisplay */
    protected void showLine(String s) {
        if (lines.size() == 20)
            lines.removeElementAt(0);
        lines.addElement(s);
        repaint();
    }

    /** This method repaints the text in the window */
    public void paint(Graphics g) {
        for (int i = 0; i < lines.size(); i++)
            g.drawString((String) lines.elementAt(i), 20, i * 16 + 50);
    }
}