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.