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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

1988.0. "pixmap question" by BRSDVP::LEFEBVRE () Wed Jan 03 1990 07:28

    Hi,
    
    I am very new in Decwindow and have one question from client
    wich is very very precise.
    
    In wich memory is stored the pixmap ? 
     
    What is the relation between the size done for pixmap and the strorage
    of this is memory ?
    
    Thanks a lot for those precisions
    
    Pascale Lefebvre (TSC Bruxelles)
T.RTitleUserPersonal
Name		DateLines
1988.1DECWIN::FISHERBurns Fisher 381-1466, ZKO3-4/W23Wed Jan 03 1990 15:4526
Hi...

All my answers are for VMS only.
    
    In wich memory is stored the pixmap ? 

A pixmap is normally stored in the non-visible portion of the frame buffer
memory (so called offscreen memory).  When this gets full, the pixmap data
will be copied into virtual memory.  This is true of the VMS hardware
accelerated systems only (GPX, Firefox, Scanproc).  On a monochrome frame
buffer, it is in virtual memory.  (This is the virtual memory of the server,
not the client).
     
    What is the relation between the size done for pixmap and the strorage
    of this is memory ?

Roughly, take the number of bytes per pixel (1 for GPX and 8-plane FireFox
and 4 for a 24-plane Firefox, one-eighth for an MFB system).  Then take the width, round it out to 32
and multiply by the bytes per pixel.  Then multiply by the height.  This should
be about the number of bytes of storage used.  If the pixmap is only depth 1
on the GPX systems, you can fit more of them in offscreen memory, since they
overlay each other in different planes of offscreen memory.  This calculation
is quite approximate.  Maybe someone else can fill in the details.

Burns
1988.2thanksBRSSWS::LEFEBVREThu Jan 04 1990 06:304
    Thank a lot for these information dear specialist in decwindow. It is
    exactly the answers that I expected.
    
    Pascale.