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# Class browser.Applet

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

public class Applet
extends Object

Base applet class. All applets are subclasses of this class. Once the applet is loaded it is associated with an AppletDisplayItem in which it can draw. An applet's life is summarized by four methods:

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.

When an applet is started it cannot directly draw to the screen. Instead it needs to call repaint(). This will cause the paint(Graphics) method of the applet to be called as soon as possible. This mechanism is needed so that the applet will not get confused when the document in which it is embedded is scrolled or resized.

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);
    	    }
    	}

To try it out you need to add this in an html file.

    	<app class="HelloInternet">

See Also:
  AppletDisplayItem
Author:
  Chris Warth, Arthur van Hoff
Version:
  1.32, 20 Mar 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()

##

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.
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)

##

item

      public AppletDisplayItem item

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

documentURL

      public URL documentURL

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

appletURL

      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.

tag

      public TagRef tag

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

width

      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

height

      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

font

      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

fgColor

      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

bgColor

      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

##

Applet

      public Applet()

##

repaint

      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.

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

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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