
RefreshApplet
=============

This applet implements a component showing an image. The image is fetched
from a given URL and will be dynamically reloaded whenever the remote server
updates it. This is useful if, e.g., a webcam periodically pushes single 
pictures onto a server. The displayed images won't flicker because the 
drawing routine will wait until the image update has been completed if 
necessary. 

Warning : Race conditions might be possible when the image update period
          matches the video server's upload interval.


Usage :
-------

    <APPLET code="Refresh.class" width=384 height=288>
      <PARAM name="url" value="http://www.videoserver.de/fullsize.jpg">
      <PARAM name="period" value="1000">
      <PARAM name="showtime" value="1">
      No Java available!
    </APPLET>

The image will be zoomed or shrinked to fit into the given dimension.


Parameters :
------------

url      - URL of the remote image
period   - Polling period in microseconds
showtime - If '1', the images creation date and time are displayed in the
           lower right corner

Gimmicks :
----------

Pressing the right mouse button will reveal a pulldown menu where 

* the updating can be stopped or restarted, 

* the current images time stamp can be displayed and 

* the image can be flipped.


Changes :
---------

v0.9  : Completely rewritten from Sergueys code for maintainability
v0.91 : Image length bug coming with firmware version 2.1 fixed  
v0.92 : extractDate() made immune against variable JPEG header lengths





