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XdbeGetVisualInfo(3)              X FUNCTIONS             XdbeGetVisualInfo(3)


NAME

       XdbeGetVisualInfo - Get dbe Visual Informations


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 1.3.4            XdbeGetVisualInfo(3)

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