From: "S.E. Morris" <###@###.###>
To: ###@###.###
Subject: Idea for ImageIcon.
Cc: "S.E. Morris" <###@###.###>
Date: Wed, 24 Mar 1999 13:57:53 +0000 (GMT)

Swing gives you the ability to add images to many of it's GUI
components via the ImageIcon class - however there is a rather
annoying limitation of ImageIcon which I'd like to prepose a fix
to.

ImageIcon's (as far as I can tell) can only be created from
complete 'Image's - ie: it uses the whole of the image you give
it as the icon. When loading images across a network -
particularly something like the Internet - fetching multiple
files is tedious and slow. The overhead alone in creating,
for example, a separate HTTP request to a web server for each
image can be quite large. Even having multiple image files
in a non-networked application can be too much hassle sometimes.

Some of us more enterprising souls have therefore taken to
blocking multiple icon-style images into a single file (I think
this is commonly known as an 'image sheet'!). An example of what
I mean is this file, intended for use as button icons for an
e-mail applet:
http://www.csc.liv.ac.uk/~fish/java/MerseyMail/icons.gif

(Don't laugh - I'm a programmer not an artist!!)

The above icons are used in my own pre-Swing icon buttons
(subclassed from Canvas) which allowed you to specify a x and y
offset into the image as well as a width and height for the area of
the Image that the button icon would use. For a real example see:
http://anfield.merseyworld.com/chat/detach.html
http://anfield.merseyworld.com/chat/icons2.gif

When I use ImageIcon I have to extract an Image from my 'sheet'
before passing it in to ImageIcon. This is a lot of hassle and
creates a separate Image object for each ImageIcon to hold.
It would be nice if I could pass the same Image into each
ImageIcon but with a different x/y offset and width/height.
Less hassle and probably slightly more memory efficient.

Perhaps a new constructor type:

ImageIcon(Image i,int x,int y,int w,int h)

... might do the trick? And/or just add a new method, something
along the lines of:

public void setIconDisplayArea(int x,int y,int w,int h)


Anyway, that's my 2 pence worth. You're probably going to
tell me there's some blatantly obvious way to do the above that
I have complete missed, but anyway thanks for listening...

-FISH- ><>

(S.E. Morris - lead Java bod at Connect, the University of
Liverpool's Internet R+D Centre)