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
R XeviQueryExtension,
if any of these routines are
called with a display that does not support the extension, the
ExtensionErrorHandler (which can be set with
R XSetExtensionErrorHandler
and functions the same way as
R XSetErrorHandler )
will be called and the function will then return.
R XeviQueryExtension
returns
R True
if the Extended Visual Information extension is available on the given display.
A client must call
R 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).
R XeviQueryVersion
returns
R 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.
R 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
R 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
R 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
R 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.
