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From: amathur@alpha.ces.cwru.edu (Alok Mathur)
Newsgroups: comp.windows.x
Subject: Creating & Installing a Colormap
Message-ID: <1991Apr19.231843.28085@usenet.ins.cwru.edu>
Date: 19 Apr 91 23:18:43 GMT
Sender: news@usenet.ins.cwru.edu
Organization: Case Western Reserve University
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Originator: amathur@sandy.CES.CWRU.Edu
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Hi !

I am using Xlib and  need to install a colormap with very specific RGB
values for each pixel. I basically want to specify shades of 1 color
with increasing intensities. 
eg.
R	G	B
250	20	20
245	20	20
240	20	20

I am new to X programming. I have tried XCreateColormap & XStoreColor
but that doesn't seem to work.

I have created a window using XCreateSimpleWindow.
I then do the following :

  created = XCreateColormap(display,window,visual,AllocAll);
  for(i=1;i<=40;i++)
  {
	clr.red = 20;
	clr.green = 255 - i*5;
	clr.blue = 20;
	clr.pixel = (unsigned long) i;
	clr.flags = DoRed | DoGreen | DoBlue;
	XStoreColor(display,created,&clr);
  }

Later I raise the window and use

  for(i=1;i<=40;i++)
  {
     XSetForeground(display,gc,(unsigned long) i);
     XFillRectangle(display,window,gc,10,10,100,100);
     XFlush(display);
  }

I get a black, red, blue, yellow, grey, green, black, black, ..... black, ....
rectangles and not shades of green. Even if I vary values of red,
green, blue, I still get the same colored rectangles.
I am unable to install the colormap at all as even if I omit the
XStoreColor loop, I get the same colors.

I have also tried include XInstallColormap & XSetWindowColormap
commands before raising the window, but that doesn't help either and  I
still get the same colored rectangles.

Could someone help me out with my problem ?

Thanks a lot,

Alok.

I am using a SUN 3/60 and SunOS 4.1
The following is relevant information from xdpyinfo

screen #0:
  depths (2):    1, 8
  root window id:    0x8006e
  depth of root window:    8 planes
  number of colormaps:    minimum 1, maximum 1
  default colormap:    0x8006b
  default number of colormap cells:    256
  preallocated pixels:    black 1, white 0
  options:    backing-store YES, save-unders YES
  number of visuals:    6
  default visual id:  0x80064
  visual:
    visual id:    0x80064
    class:    PseudoColor
    depth:    8 planes
    size of colormap:    256 entries
    red, green, blue masks:    0x0, 0x0, 0x0
    significant bits in color specification:    8 bits