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Conference bulova::decw_jan-89_to_nov-90

Title:DECWINDOWS 26-JAN-89 to 29-NOV-90
Notice:See 1639.0 for VMS V5.3 kit; 2043.0 for 5.4 IFT kit
Moderator:STAR::VATNE
Created:Mon Oct 30 1989
Last Modified:Mon Dec 31 1990
Last Successful Update:Fri Jun 06 1997
Number of topics:3726
Total number of notes:19516

2474.0. "Rendering Images on non-DEC systems" by TOWNS::SWEATT () Mon Mar 19 1990 21:23

    
    	I'm seeing a bit of weird problem right now.  I apologize if its
    been mentioned before, the system is running so slowly right now, I
    can't imagine wading through all 2400 messages to find out.
    
    	Anyway...  When running DECwindows 2.0 on a VAXstation 3100 and
    displaying to a non-DEC system,  (Both Apollo, and IBM AIX) there is a
    problem when attempting to display images.  For example, running
    DECwrite on the VAX, displaying on the Apollo.  If the DECwrite
    document has a link to a TIFF image, there is a problem when displayed
    on the Apollo.   There is no problem from VAX to VAX or VAX to
    Ultrix/RISC.  I don't really understand how the VAX sends the image
    data.  It appears that the image is sliced vertically, then sent in
    pieces.  Unfortunately it appears to be sending the vertical slices
    backwards.  I mean in a mirror context.  Such as the letters d and b. 
    Consequently, the image looks sliced up  Could this be a byte-order
    problem?  Has anybody seen this before?
    
    Bill
    
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2474.1MU::PORTERbliss is ignoranceMon Mar 19 1990 22:0816
    Sounds like a bit-order-within-the-byte problem!
    
    I believe, but I don't have my X bible at hand, that in the
    specific case of images, the client is reponsible for
    delivering the bit order that the server needs.  (The
    hardware defines whether it displays low-bit-first or
    high-bit-first, and the server passes the image unchanged
    to the hardware; the argument was "efficiency").
    
    This translates into "if your application code doesn't 
    support big-endian formats you're out of luck".
    
    
    This at least is the way I remember it working, but
    it's been a while since I looked.
    
2474.2STAR::KLEINSORGEFred Kleinsorge, VMS DevelopmentTue Mar 20 1990 10:326
    
    .1 ... if it really is the clients problem, then isn't it Xlib's
    	   responsibility then to reverse the bits?  Surely the actual
    	   application should'nt need to worry about big/little-endian
    	   problems.
    
2474.3Is it fixable?TOWNS::SWEATTTue Mar 20 1990 11:319
    
    	Geez, it didn't take long for this topic to go over my head.  My
    apologies, but I am not familiar enough with the bit level internals of
    X.  From a user standpoint, do you know who is responsible?  Should DEC
    be attempting a fix?  Has an SPR been written?  Any ideas how to fix
    the problem?  Thanks again.
    
    Bill
    
2474.4QAR problem against DECwriteSTAR::VATNEPeter Vatne, VMS DevelopmentTue Mar 20 1990 13:2510
Any problems with displaying images on another vendor's server should
be QARed against the particular application.  Although this might possibly
be a problem in the other vendor's server, since it happens with both IBM
and Apollo, I would bet the problem is on our end.  If the DECwrite folks
have to pass the buck to someone else, let them do it.

Don't worry about whether someone else has filed an SPR.  Your case might
be different from someone else's problem that sounds similar.  Even if it
is the exact same problem, your example might be the one that makes it
possible for the developer to solve the problem.
2474.5GERUND::WOLFEThree dimensional programming on a 2-D screenTue Mar 20 1990 18:113
    This is a DECwrite bug. It's on the list of things to be fixed for our
    V1.1....
    			Pete
2474.6MU::PORTERbliss is ignoranceTue Mar 20 1990 23:095
    re .2
    
    No.  [don't shoot me, I'm only the messenger].
    
    
2474.7What is this one?DECWIN::FISHERPrune Juice: A Warrior's Drink!Wed Mar 21 1990 17:1413
    Just out of curiosity, and also to set the record straight:
    
    In the Ximage data structure, you tell Xlib the endianness of your
    image.  When you do a PutImage, Xlib compares the image info with what
    the server wants, and swaps it if it is different.  Thus applications
    that don't lie to xlib should not be concerned about opposite
    endianness.
    
    Is this the DECwrite problem?  Are you just filling in the data
    structure different from what the data actually is?  Is there something
    else that other application writers should be careful of?
    
    Burns
2474.8Ultrix Globe Demo also ErrsTOWNS::SWEATTWed Mar 21 1990 20:128
    
    	By the way, I've noticed the same behavior with the globe demo on
    Ultrix.  I suppose I should consult the DECwrite notes forum, but does
    anybody know more about DECwrite 1.1?  What is being fixed/enhanced,
    when will it be released, stuff like that.
    	Thanks alot for your help.
    
    Bill