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From: courtney@chassel.cps.msu.edu (Jonathan Courtney)
Newsgroups: comp.windows.open-look
Subject: server images
Message-ID: <1991Apr3.173428.27898@msuinfo.cl.msu.edu>
Date: 3 Apr 91 17:34:28 GMT
Sender: news@msuinfo.cl.msu.edu
Reply-To: courtney@chassel.cps.msu.edu (Jonathan Courtney)
Organization: PRIP Lab, Comp. Sci. Dept., MSU
Lines: 48


  Recently I posted a request for help with XView colormap segments.  As it
turned out, the problem was not one with my colormap segment, but with the
server image that I was using to test it.  Which led me to an entirely
different dilemma:

  I am creating an xview server image that should be a simple gray ramp with
values from 0-255.  Yet when I display the image, only colors from 0-127 are
displayed.  It turns out that the xv_create call actually zeroes out the data
with values >= 128.  It sounds to me like a sign problem, but the same data
works with XCreateImage calls just fine.  Any thoughts?

==========
#include <xview/svrimage.h>

Server_image image;
char* buffer;
int i, j;

  ...

  buffer = (char*)malloc(256*256);

  /* Make the gray ramp */
  for (i=0; i<256; i++)
    for (j=0; j<256; j++)
      buffer[i*256+j] = j;


  /* Create the image in "X" format */
  image = xv_create(NULL, SERVER_IMAGE,
			XV_WIDTH, 256,
			XV_HEIGHT, 256,
			SERVER_IMAGE_DEPTH, 8,
			SERVER_IMAGE_X_BITS, buffer,
			SERVER_IMAGE_COLORMAP, "my_colormap",
			NULL);

==============

  And then I use the image in a PANEL_LIST object.

  Again, any help is greatly appreciated.

							Jon