Path: utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!wuarchive!rex!uflorida!gatech!bloom-beacon!SABER.COM!jimf
From: jimf@SABER.COM
Newsgroups: comp.windows.x
Subject: Re: XImages
Message-ID: <9012101728.AA23279@test4>
Date: 10 Dec 90 17:28:11 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 34

|So you have only two real possibilities.  One is that you can massage
|your data into whatever format the server you happen to be connected to
|wants.  The other is to write your own functions to stuff into the
|function handles, allocate the XImage structure yourself, and use
|whatever data layout happens to be convenient.
|
|IMO this is a botch.  It should be possible to use your own preferred
|data layout and have Xlib do whatever is necessary to accomodate it.
|It more or less has to do this anyway, because the handles do not
|include functions for PutImage and GetImage format conversion.

Yea, the XImage stuff is not well designed or documented.  It's highly
portable, though, to allocate an XImage and smash the attributes you
want into the structure.  Xlib (at least all of them I've used) will
convert to server-natural format for you.  This is highly convenient
because all you have to do is describe what your image looks like and
send it off.

Sample code which does this can be had from expo.lcs.mit.edu in
/contrib/xloadimage.2.02.tar.Z.  Look at send.c.

While I admit that it's not the cleanest way to do things and it
doesn't seem to be guaranteed that Xlib will convert for you, it does
work very portably (ie I know of no system which doesn't convert, and
xloadimage runs on a *lot* of systems).

Nice description, BTW.  I would have killed for that a couple of years
ago :-).

Happy hacking,

jim frost
saber software
jimf@saber.com