XeviQueryExtension(3)

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 proto-
       col 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 XSetExten-
       sionErrorHandler 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  Xevi-
       QueryExtension  before calling any other EVI function in order to nego-
       tiate 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 over-
       lays and/or underlay planes, and information that  allows  applications
       better  to  determine  the  level of hardware support for multiple col-
       ormaps. 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  ele-
       ments 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  trans-
       parency 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_con-
       flicts.   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 mem-
       ory allocation failure.

X Version 11                     libXext 1.0.3                         XEVI(3)