Java Foundation Classes in a Nutshell

Example 7−2: An Applet That Uses the Java 1.0 Event Model (continued)

this.requestFocus(); // Ask for keyboard focus so we get key events

}

/** Respond to mouse clicks */

public boolean mouseDown(Event e, int x, int y) {

lastx = x; lasty = y; // Remember where the click was

return true;

}

/** Respond to mouse drags */

public boolean mouseDrag(Event e, int x, int y) {

g.setColor(Color.black);

g.drawLine(lastx, lasty, x, y); // Draw from last position to here

lastx = x; lasty = y; // And remember new last position

return true;

}

/** Respond to key presses: erase drawing when user types 'e' */

public boolean keyDown(Event e, int key) {

if ((e.id = = Event.KEY_PRESS) && (key = = 'e')) {

g.setColor(this.getBackground());

g.fillRect(0, 0, bounds().width, bounds().height);

return true;

}

else return false;

}

/** Respond to button clicks: erase drawing when user clicks button */

public boolean action(Event e, Object arg) {

if (e.target = = erase_button) {

g.setColor(this.getBackground());

g.fillRect(0, 0, bounds().width, bounds().height);

return true;

}

else return false;

}

}

Inc luding Applets in HTML Files

Applets are typically embedded in HTML files using the <APPLET> tag. Another

alter native relies on a Java Plug-in and uses the

<EMBED> and <OBJECT> tags. Multi-

ple applet files can be combined into a single JAR (Java Archive) file that a web

br owser can read as a single, compressed file, substantially reducing download ...