XEVI(3X11) X FUNCTIONS XEVI(3X11)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 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.
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XEVI(3X11) X FUNCTIONS XEVI(3X11)
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.
ERRORSXeviGetVisualInfo 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.
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