XdbeGetVisualInfo(3) X FUNCTIONS XdbeGetVisualInfo(3)

NAME

XdbeGetVisualInfo - Get dbe Visual Information

SYNOPSIS

#include <X11/extensions/Xdbe.h>

XdbeScreenVisualInfo *XdbeGetVisualInfo(
Display *dpy,
Drawable *screen_specifiers,
int *num_screens)

DESCRIPTION

This function returns information about which visuals support double
buffering. The argument num_screens specifies how many elements
there are in the screen_specifiers list. Each drawable in
screen_specifiers designates a screen for which the supported visuals
are being requested. If num_screens is zero, information for all
screens is requested. In this case, upon return from this function,
num_screens will be set to the number of screens that were found. If
an error occurs, this function returns NULL, else it returns a
pointer to a list of XdbeScreenVisualInfo structures of length
num_screens. The nth element in the returned list corresponds to the
nth drawable in the screen_specifiers list, unless num_screens was
passed in with the value zero, in which case the nth element in the
returned list corresponds to the nth screen of the server, starting
with screen zero. The XdbeScreenVisualInfo structure has the
following fields:

int count
XdbeVisualInfo *visinfo

count specifies the number of items in visinfo. visinfo specifies a
list of visuals, depths, and performance hints for this screen.

The XdbeVisualInfo structure has the following fields:

VisualID visual
int depth
int perflevel

visual specifies one visual ID that supports double-buffering. depth
specifies the depth of the visual. perflevel is a performance hint.

The only operation defined on a perflevel is comparison to a
perflevel of another visual on the same screen. The visual having
the higher perflevel is likely to have better double-buffering
graphics performance than the visual having the lower perflevel.
Nothing can be deduced from the following: the magnitude of the
difference of two perflevels, a perflevel value in isolation, or
comparing perflevels from different servers.

ERRORS

BadDrawable
One or more values passed in screen_specifiers is not a valid
drawable.

SEE ALSO

DBE, XdbeAllocateBackBufferName(), XdbeBeginIdiom(),
XdbeDeallocateBackBufferName(), XdbeEndIdiom(), XdbeFreeVisualInfo(),
XdbeGetBackBufferAttributes(), XdbeQueryExtension(),
XdbeSwapBuffers().


X Version 11 libXext 1.3.6 XdbeGetVisualInfo(3)