XEVI(3) X FUNCTIONS XEVI(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 de-
scribed below. With the exception of XeviQueryExtension, if any of
these routines are called with a display that does not support the ex-
tension, 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 ex-
tension 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 un-
defined 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 re-
turned 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 transpar-
ency 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 1.3.4 XEVI(3)
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