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Class browser.Applet

java.lang.Object
   |
   +----browser.Applet

public class Applet

extends Object

init()

This method is called after the applet is created. The applet can use this method to resize itself, download resources, get fonts, get colors, etc.

start()

This method is called when the applet's document is visited. The applet can use this method to start a background thread for animation, to play a sound etc.

stop()

This method is called when the applet's document is no longer on the screen. The applet should stop any thread it has forked and any long sounds that are playing. It is garanteed to be called before the applet is destroyed.

destroy()

This method is called when the applet is discarded. It is the last opportunity for the applet to clean up its act! Calls stop() if the applet is still active.

The applet class contains various method that help you get images, get fonts, play audio, etc. If you can use these methods instead of doing the work yourself, they are more likely to be supported in the future.

Here is a very simple example of an applet.

	import awt.*;
	import browser.*;
	public class HelloInternet extends Applet {
	    public void init() {
		resize(150, 25);
	    }
	    public void paint(Graphics g) {
		g.drawString("Hello Internet!", 5, 20);
	    }
	}

	<app class="HelloInternet">

See Also:

AppletDisplayItem

Author:

Chris Warth, Arthur van Hoff

Version:

1.35, 13 May 1995

appletURL

The URL of the applet.

bgColor

The background color of the applet.

documentURL

The URL of the document in which the applet is embedded.

fgColor

The foreground color of the applet.

font

The font of the applet.

height

The height of the applet.

item

The display item in which this applet is being displayed.

tag

The tag.

width

The width of the applet.

Applet()

createImage(int, int)

Creates an image given a width and height.

destroy()

Cleans up whatever resources are being held.

getAttribute(String)

Gets an attribute out of theapplet's app tag.

getAudioData(String)

Gets audio data given a name.

getAudioData(URL)

Gets audio data given a url.

getAudioStream(URL)

Gets an audio stream given a url.

getColor(int, int, int)

Gets a Color.

getContinuousAudioStream(URL)

Gets a continuous audio stream given a URL.

getFocus()

Gets the focus.

getFont(String, int)

Gets a font with the given font name and size.

getFont(String, int, int)

Gets a font with the given font name, style, and size.

getFontMetrics(Font)

Gets the metrics for the given font.

getImage(String)

Gets an image given an image name.

getImage(URL)

Gets an image given a URL.

gotFocus()

Got focus.

init()

Initializes the applet.

isActive()

Returns true if the applet is started.

keyDown(int)

A character is typed inside the applet and it has the focus.

lostFocus()

Lost focus.

mouseDown(int, int)

Mouse down.

mouseDrag(int, int)

Mouse drag (the mouse button is down).

mouseEnter()

Called when the mouse enters the applet (regardless of the mouse button state).

mouseExit()

Called when the mouse exits the applet (regardless of the mouse button state).

mouseMove(int, int)

Mouse move (the mouse button is up).

mouseUp(int, int)

Mouse up.

paint(Graphics)

Paints the applet, given a graphics context.

play(String)

Plays an audio sample.

play(AudioData)

Plays an audio sample.

repaint()

Repaints the applet, this will actually happen at some later time.

resize(int, int)

Resizes the applet.

showDocument(URL)

Shows a Document.

showStatus(String)

Shows a status string at the bottom of the HotJava window.

start()

Called to start the applet.

startPlaying(InputStream)

Starts playing a stream of audio data.

stop()

Called to stop the applet.

stopPlaying(InputStream)

Stops playing a stream of audio data.

update(Graphics)

  public AppletDisplayItem item

The display item in which this applet is being displayed. Don't modify it.

  public URL documentURL

The URL of the document in which the applet is embedded. Don't modify it.

  public URL appletURL

The URL of the applet. This can differ from the documentURL when a "src" attribute is specified in the app tag. Don't modify it.

  public TagRef tag

The tag. Use getAttribute() to get attributes in the tag. Don't modify it.

See Also:

getAttribute

  public int width

The width of the applet. Use resize() to change the size of the applet and the display item in which it is located. You can change it by calling resize().

See Also:

resize

  public int height

The height of the applet. Use resize() to change the size of the applet and the display item in which it is located. You can change it by calling resize().

See Also:

resize

  public Font font

The font of the applet. This font will be set when the paint() method is called. If you want to modify it, you need to do this in the init() method. This variable is initialized to an initial value, feel free to modify it.

See Also:

paint, init

  public Color fgColor

The foreground color of the applet. This color will be the foreground color when the paint() method is called. This variable is initialized to an initial value, feel free to modify it.

See Also:

paint

  public Color bgColor

The background color of the applet. This color is the background color of the window the applet is in when the applet was created.

See Also:

paint

  public Applet()

  public void repaint()

Repaints the applet, this will actually happen at some later time. To actually paint the applet HotJava will call the paint() method.

See Also:

paint

resize

  public void resize(int width,
                     int height)

Resizes the applet. You should resize the applet in the init() method. Resizing the applet at another time may cause the document to be reformatted. Don't worry about calling repaint(), resize will do the right thing for you.

See Also:

repaint

isActive

  public boolean isActive()

Returns true if the applet is started. This will be true from just before start() is called until just after stop() is called.

getAttribute

  public String getAttribute(String name)

Gets an attribute out of theapplet's app tag. Note that the width and height attributes are used to determine the initial dimensions of the applet.

Returns:

the attribute value or null if the attribute is not defined.

getImage

  public Image getImage(String name)

Gets an image given an image name. The name is assumed to be relative to the appletURL. If the image can't be found there, the documentURL is used.

Returns:

the image or null if something went wrong.

createImage

  public Image createImage(int width,
                           int height)

Creates an image given a width and height. This is useful to do double-buffered graphics which can be done by creating a Graphics object that points to this image and then drawing directly to the image.

See Also:

Graphics

Returns:

the image or null if something went wrong.

getImage

  public Image getImage(URL url)

Gets an image given a URL.

Returns:

the image or null if something went wrong.

getAudioData

  public AudioData getAudioData(String name)

Gets audio data given a name. The name is assumed to be relative to the appletURL. If the data can't be found there, the documentURL is used.

Returns:

the audio data or null if it could not be found.

See Also:

play

getAudioData

  public AudioData getAudioData(URL url)

Gets audio data given a url.

Returns:

the audio data or null if the URL is invalid.

See Also:

play

getAudioStream

  public InputStream getAudioStream(URL url)

Gets an audio stream given a url. The actual audio data can be very large because it will be read as the audio is being played.

Returns:

the stream or null if the URL is invalid.

See Also:

startPlaying

getContinuousAudioStream

  public InputStream getContinuousAudioStream(URL url)

Gets a continuous audio stream given a URL. Note that all of the data will read before the stream can be used.

Returns:

the stream or null if the URL is invalid.

See Also:

startPlaying

play

  public void play(String name)

Plays an audio sample. The data is obtained using getAudioData(). Nothing happens if the data could not be found.

See Also:

getAudioData

play

  public void play(AudioData data)

Plays an audio sample.

startPlaying

  public void startPlaying(InputStream stream)

Starts playing a stream of audio data. Use stopPlaying to stop the audio from playing.

See Also:

getAudioStream, stopPlaying

stopPlaying

  public void stopPlaying(InputStream stream)

Stops playing a stream of audio data.

See Also:

startPlaying

showStatus

  public void showStatus(String msg)

Shows a status string at the bottom of the HotJava window.

showDocument

  public void showDocument(URL doc)

Shows a Document.

getFont

  public Font getFont(String name,
                      int size)

Gets a font with the given font name and size.

See Also:

Font

getFont

  public Font getFont(String name,
                      int style,
                      int size)

Gets a font with the given font name, style, and size.

See Also:

Font

getFontMetrics

  public FontMetrics getFontMetrics(Font font)

Gets the metrics for the given font.

See Also:

FontMetrics

getColor

  public Color getColor(int r,
                        int g,
                        int b)

Gets a Color.

See Also:

Color

init

  protected void init()

Initializes the applet. You never need to call this directly, it is called automatically by HotJava once the applet is created.

start

  protected void start()

Called to start the applet. You never need to call this method directly it is called when the applet's document is visited.

See Also:

stop

stop

  protected void stop()

Called to stop the applet. It is called when the applet's document is no longer on the screen. It is guaranteed to be called before destroy() is called. You never need to call this method directly.

See Also:

start, destroy

destroy

  protected void destroy()

Cleans up whatever resources are being held. If the applet is active it is first stopped.

See Also:

stop

paint

  public void paint(Graphics g)

Paints the applet, given a graphics context. The origin will be in the topleft corner of the applet. The clipping area is set to the exact size of the applet. The font, foreground color and background color are set to default values.

You never have to call this method explicitly! It will be called automatically by HotJava in response to damage or expose events, or when you call repaint().

See Also:

repaint

update

  public void update(Graphics g)

mouseDown

  public void mouseDown(int x,
                        int y)

Mouse down. The x,y coordinates are relative to the applet's top left corner. A call to mouseUp() is guaranteed to follow when the mouse is released. mouseDrag is called when the mouse is moved.

See Also:

mouseUp, mouseDrag

mouseDrag

  public void mouseDrag(int x,
                        int y)

Mouse drag (the mouse button is down). The x,y coordinates are relative to the applet's top left corner.

mouseUp

  public void mouseUp(int x,
                      int y)

Mouse up. The x,y coordinates are relative to the applet's top left corner. This must have been preceded by a call to mouseDown().

See Also:

mouseDown

mouseMove

  public void mouseMove(int x,
                        int y)

Mouse move (the mouse button is up). The x,y coordinates are relative to the applet's top left corner.

mouseEnter

  public void mouseEnter()

Called when the mouse enters the applet (regardless of the mouse button state). A call to mouseExit is guaranteed to follow.

See Also:

mouseExit

mouseExit

  public void mouseExit()

Called when the mouse exits the applet (regardless of the mouse button state). Must have been preceded by a call to mouseEnter().

See Also:

mouseEnter

getFocus

  public void getFocus()

Gets the focus. This is usually called in the mouseDown() method. A gotFocus() call will follow.

See Also:

gotFocus, mouseDown

gotFocus

  public void gotFocus()

Got focus. The user can now type into the applet.

See Also:

keyDown

lostFocus

  public void lostFocus()

Lost focus.

keyDown

  public void keyDown(int key)

A character is typed inside the applet and it has the focus.

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