XEVI(3)                    X FUNCTIONS                    XEVI(3)



NAME
       XeviQueryExtension,  XeviQueryVersion, XeviGetVisualInfo -
       X Extended Visual Information functions

SYNOPSIS
       #include 

       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 Xevi-
       QueryExtension, if any of these routines are called with a
       display  that  does  not support the extension, the Exten-
       sionErrorHandler (which can  be  set  with  XSetExtension-
       ErrorHandler  and  functions the same way as XSetErrorHan-
       dler) 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 pro-
       tocol 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  sup-
       ported  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 infor-
       mation  relevant  for  systems  supporting overlays and/or
       underlay planes, and information that allows  applications
       better to determine the level of hardware support for mul-
       tiple colormaps. XeviGetVisualInfo returns Success if suc-
       cessful,  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 visu-
       als 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  ExtendedVisual-
       Info.  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 nor-
       mal planes, > 0 for overlays, < 0 for underlays.

       transparency_type returns the type  of  transparency  sup-
       ported  by the visual. XEVI_TRANSPARENCY_NONE if there are
       no  transparent  pixels,  XEVI_TRANSPARENCY_PIXEL  if  the
       visual   supports   a   transparent   pixel,   XEVI_TRANS-
       PARENCY_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_TRANS-
       PARENCY_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 col-
       ormap. For example, if a 12-bit hardware colormap is over-
       loaded 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  ille-
       gal visual ID, BadAccess if the X server does not respond,
       BadAlloc if there is a memory allocation failure.



X Version 11              libXext 1.0.4                   XEVI(3)