NAME

       XeviQueryExtension,  XeviQueryVersion,  XeviGetVisualInfo  - X Extended Visual Information
       functions

SYNOPSIS

       #include <X11/extensions/XEVI.h>

       Bool XeviQueryExtension (Display *dpy);

       Bool XeviQueryVersion (Display *dpy,
           int *major_version_return,
           int *minor_version_return);

       int XeviGetVisualInfo (Display *dpy, VisualID *visual,
           int n_visual, ExtendedVisualInfo ** evi_return,
           int * n_info_return);

DESCRIPTION

       The X11  Extended  Visual  Information  extension  (EVI)  allows  a  client  to  determine
       information about core X visuals beyond what the core protocol provides.

       The EVI application programming library contains the interfaces described below.  With the
       exception of XeviQueryExtension, if any of these routines are called with a  display  that
       does  not  support  the  extension,  the  ExtensionErrorHandler  (which  can  be  set with
       XSetExtensionErrorHandler and functions the same way as XSetErrorHandler) will  be  called
       and the function will then return.

       XeviQueryExtension  returns True if the Extended Visual Information extension is available
       on the given display.  A client must call XeviQueryExtension before calling any other  EVI
       function  in  order  to negotiate a compatible protocol version; otherwise the client will
       get undefined behavior (EVI may or may not work).

       XeviQueryVersion returns True if the request succeeded; the values of the major and  minor
       protocol  version  supported  by  the  server  are  returned  in  major_version_return and
       minor_version_return.

       XeviGetVisualInfo returns a list of ExtendedVisualInfo  structures  that  describe  visual
       information  beyond  that  supported by the core protocol. This includes layer information
       relevant for systems supporting overlays and/or  underlay  planes,  and  information  that
       allows  applications  better  to  determine  the  level  of  hardware support for multiple
       colormaps. XeviGetVisualInfo returns Success if successful, or an X error  otherwise.   If
       the  argument visual is NULL, then information for all visuals of all screens is returned.
       Otherwise, it's a pointer to a list of visuals for which extended  visual  information  is
       desired.   n_visual  is  the number of elements in the array visual.  evi_return returns a
       pointer to a list of ExtendedVisualInfo. When done, the client should free the list  using
       XFree.  n_info_return returns the number of elements in the array evi_return.

       The ExtendedVisualInfo structure has the following fields:
            VisualID        core_visual_id
            int             screen
            int             level
            unsigned int    transparency_type
            unsigned int    transparency_value
            unsigned int    min_hw_colormaps
            unsigned int    max_hw_colormaps
            unsigned int    num_colormap_conflicts
            VisualID *      colormap_conflicts

       The  combination  of  core_visual_id  and  screen number uniquely specify the visual being
       described.

       level returns the level number for the visual, 0 for normal planes, > 0 for overlays, <  0
       for underlays.

       transparency_type   returns   the   type   of   transparency   supported  by  the  visual.
       XEVI_TRANSPARENCY_NONE if there are no transparent pixels, XEVI_TRANSPARENCY_PIXEL if  the
       visual  supports  a  transparent  pixel,  XEVI_TRANSPARENCY_MASK  if  the  visual supports
       transparent plane(s).

       transparency_value  returns  the  pixel/plane   value   to   set   for   transparency   if
       transparency_type isn't XEVI_TRANSPARENCY_NONE.

       min_hw_colormaps  and  max_hw_colormaps  return the minimum and maximum number of hardware
       colormaps backing up the visual.

       num_colormap_conflicts returns the number of elements in colormap_conflicts.   This  array
       returns  a  list  of visuals that may cause conflicts in the use of the hardware colormap.
       For example, if a 12-bit hardware colormap is overloaded to support 8-bit  colormaps,  the
       corresponding 8-bit visuals would conflict with the 12-bit visuals.

ERRORS

       XeviGetVisualInfo  will return BadValue if passed an illegal visual ID, BadAccess if the X
       server does not respond, BadAlloc if there is a memory allocation failure.