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XeviQueryExtension(3X11)
X11R6
NAME
  XeviQueryExtension, XeviQueryVersion, XeviGetVisualInfo - determine
  information about core X visuals

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 );

ARGUMENTS
  dpy Specifies the connection to the X server.

  evi_return
      Returns a pointer to a list of ExtendedVisualInfo. When done, the
      client should free the list using XFree.

  major_version_return
      Returns the value of the major protocol version supported by the
      server.

  minor_version_return
      Returns the value of the minor protocol version supported by the
      server.

  n_info_return
      Returns the number of elements in the evi_return array.

  n_visual
      Specifies the number of elements in the visual array.

  visual
      Specifies the visuals for which the extended visual information is
      needed. If this argument is NULL, information for all visuals of all
      screen is returned.

DESCRIPTION
  The X11 Extended Visual Information extension (EVI) provides information
  about core X visuals beyond that which the core protocol provides.

  The EVI application programming library contains the XeviQueryExtension,
  XeviQueryVersion, and XeviGetVisualInfo interfaces. If any of these
  routines are called with a display that does not support the extension
  (with the exception of the XeviQueryExtension), the ExtensionErrorHandler
  is called and the function returns.

    ·  XeviQueryExtension returns true if the Extended Visual Information
       extension is available on the specified display. XeviQueryExtension
       must be called before other EVI functions to negotiate a compatible
       protocol version; otherwise, the result is undefined behavior.

    ·  XeviQueryVersion returns true if the request is successful.  The
       values of the major and minor protocol version that the server
       supports are returned in major_version_return and
       minor_version_return, respectively.

    ·  XeviGetVisualInfo returns a list of ExtendedVisualInfo structures
       which describe visual information beyond the information supported by
       the core protocol. The information includes layer information relevent
       to systems supporting overlays and underlays and also information that
       allows applications to determine the level of hardware support for
       multiple colormaps. XeviGetVisualInfo returns Success if successful,
       or an X error if unsuccessful.

NOTES
  The ExtensionErrorHandler can be set using XSetExtensionErrorHandler.	 It
  functions the same as XSetErrorHandler.

STRUCTURES
  The ExtendedVisualInfo structure contains 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
  _____________________________________

  core_visual_id and screen
      uniquely specify the visual being described.

  level
      contains the level number for the visual: 0 for normal planes; > 0 for
      overlays; < 0 for underlays.

  transparency_type
      contains the type of transparency that the visual supports:

      XEVI_TRANSPARENCY_NONE, no transparent pixels XEVI_TRANSPARENCY_PIXEL,
      supports a transparent pixel XEVI_TRANSPARENCY_MASK, supports
      transparent plane(s)

  transparency_value
      contains the pixel or plane value for transparency if transparency_type
      is not XEVI_TRANSPARENCY_NONE.

  min_hw_colormaps
      contains the minimum number of hardware colormaps that backup the
      visual.

  max_hw_colormaps
      contains the maximum number of hardware colormaps that backup the
      visual.

  num_colormap_conflicts
      contains the number of elements in colormap_conflicts.

  colormap_conflicts
      contains a list of visuals that may cause conflicts using 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.

DIAGNOSTICS
  XeviGetVisualInfo returns the following:

  BadAccess
      The server failed to respond.

  BadAlloc
      The server failed to allocate the requested resource or server memory.

  BadValue
      The client specified an illegal visual ID.

LEGAL NOTICES
  Copyright 1997, Silcon Graphics Computer Systems.

  See X(1X) for a full statement of rights and permissions.

SEE ALSO
  Commands:X(1)

Index for Section 3X11

Alphabetical listing for X

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