[Xprint] Re: XCreateColormap() for Pseudocolor 15bit fails

[Roland Mainz]

Roland Mainz wrote:
> > does anyone know under which conditions XCreateColormap() can fail? I
> > have selected a Pseudocolor 15bit visual but calling XCreateColormap()
> > fails all the time:
> > X Error of failed request:  BadAlloc (insufficient resources for operation)
> >   Major opcode of failed request:  78 (X_CreateColormap)
> >   Serial number of failed request:  39
> >   Current serial number in output stream:  40
> >
> > Breakpoint 1, 0x40178ab6 in exit () from /lib/libc.so.6
> > (gdb) where
> > #0  0x40178ab6 in exit () from /lib/libc.so.6
> > #1  0x40070d10 in _XDefaultError (dpy=0x8052838, event=0xbffff340) at
> > XlibInt.c:2831
> > #2  0x40070e82 in _XError (dpy=0x8052838, rep=0xbffff430) at XlibInt.c:2883
> > #3  0x4006edde in _XReply (dpy=0x8052838, rep=0xbffff430, extra=0,
> > discard=1) at XlibInt.c:1812
> > #4  0x40068762 in XSync (dpy=0x8052838, discard=0) at Sync.c:45
> > #5  0x40068825 in _XSyncFunction (dpy=0x1) at Synchro.c:34
> > #6  0x40047725 in XCreateColormap (dpy=0x8052838, w=61,
> > visual=0x8057d38, alloc=0) at CrCmap.c:51
> >
> > Any ideas, comments, opinions on what I am doing wrong?
> 
> AFAIK you're doing nothing wrong. The problem is that the core X
> protocol defines |ColormapEntries| as |CARD16| (which is AFAIK a |signed
> short|). There are two solutions:
> 1. Create a extension (XC-BIGCOLORMAP) which hooks into libX11 and
> allows larger colormaps (e.g. make the field |CARD32| and adjust the
> matching function calls).

Attached patch solves the problem (for 15bit, anything deeper needs
something like XC-BIGCOLORMAP), however it will likely break the Xfree86
Module ABI (which leads to the debate whether we should break the ABI
for 7.0) ... ;-(

----

Bye,
Roland

-- 
  __ .  . __
 (o.\ \/ /.o) roland.mainz at nrubsig.org
  \__\/\/__/  MPEG specialist, C&&JAVA&&Sun&&Unix programmer
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-------------- next part --------------
Index: xc/programs/Xserver/include/scrnintstr.h
===================================================================
RCS file: /cvs/xorg/xc/programs/Xserver/include/scrnintstr.h,v
retrieving revision 1.4
diff -u -2 -0 -r1.4 scrnintstr.h
--- xc/programs/Xserver/include/scrnintstr.h	7 Aug 2004 00:58:21 -0000	1.4
+++ xc/programs/Xserver/include/scrnintstr.h	8 Apr 2005 23:22:06 -0000
@@ -52,41 +52,41 @@
 
 #include "screenint.h"
 #include "regionstr.h"
 #include "bstore.h"
 #include "colormap.h"
 #include "cursor.h"
 #include "validate.h"
 #include "X11/Xproto.h"
 #include "dix.h"
 
 typedef struct _PixmapFormat {
     unsigned char	depth;
     unsigned char	bitsPerPixel;
     unsigned char	scanlinePad;
     } PixmapFormatRec;
     
 typedef struct _Visual {
     VisualID		vid;
     short		class;
     short		bitsPerRGBValue;
-    short		ColormapEntries;
+    unsigned long	ColormapEntries;
     short		nplanes;/* = log2 (ColormapEntries). This does not
 				 * imply that the screen has this many planes.
 				 * it may have more or fewer */
     unsigned long	redMask, greenMask, blueMask;
     int			offsetRed, offsetGreen, offsetBlue;
   } VisualRec;
 
 typedef struct _Depth {
     unsigned char	depth;
     short		numVids;
     VisualID		*vids;    /* block of visual ids for this depth */
   } DepthRec;
 
 
 /*
  *  There is a typedef for each screen function pointer so that code that
  *  needs to declare a screen function pointer (e.g. in a screen private
  *  or as a local variable) can easily do so and retain full type checking.
  */