171 lines
4.0 KiB
HTML
171 lines
4.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of XdbeGetVisualInfo</TITLE>
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</HEAD><BODY>
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<H1>XdbeGetVisualInfo</H1>
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Section: X FUNCTIONS (3)<BR>Updated: libXext 1.3.4<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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XdbeGetVisualInfo - Get dbe Visual Informations
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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#include <<A HREF="file:///usr/include/X11/extensions/Xdbe.h">X11/extensions/Xdbe.h</A>>
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<P>
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XdbeScreenVisualInfo *XdbeGetVisualInfo(
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<BR> Display *dpy,
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<BR> Drawable *screen_specifiers,
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<BR> int *num_screens)
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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This function returns information about which visuals support double
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buffering. The argument
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<I>num_screens</I>
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specifies how many elements there are
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in the
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<I>screen_specifiers</I>
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list. Each drawable in
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<I>screen_specifiers</I>
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designates a
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screen for which the supported visuals are being requested. If
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<I>num_screens</I>
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is zero, information for all screens is requested. In this case, upon return
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from this function,
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<I>num_screens</I>
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will be set to the number of screens that were
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found. If an error occurs, this function returns NULL, else it returns a
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pointer to a list of
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<I>XdbeScreenVisualInfo</I>
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structures of length
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<I>num_screens.</I>
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The nth
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element in the returned list corresponds to the nth drawable in the
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<I>screen_specifiers</I>
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list, unless
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<I>num_screens</I>
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was passed in with the value zero,
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in which case the nth element in the returned list corresponds to the nth screen
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of the server, starting with screen zero. The
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<I>XdbeScreenVisualInfo</I>
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structure has the following fields:
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<P>
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<BR> int count
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<BR> XdbeVisualInfo *visinfo
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<P>
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<I>count</I>
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specifies the number of items in
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<I>visinfo.</I>
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<I>visinfo</I>
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specifies a list of visuals, depths, and performance hints for this screen.
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<P>
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The
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<I>XdbeVisualInfo</I>
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structure has the following fields:
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<P>
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<BR> VisualID visual
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<BR> int depth
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<BR> int perflevel
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<P>
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<I>visual</I>
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specifies one visual ID that supports double-buffering.
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<I>depth</I>
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specifies the depth of the visual.
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<I>perflevel</I>
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is a performance hint.
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<P>
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The only operation defined on a
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<I>perflevel</I>
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is comparison to a
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<I>perflevel</I>
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of another visual on the same screen. The visual having the higher
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<I>perflevel</I>
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is likely to have better double-buffering graphics performance than the visual
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having the lower
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<I>perflevel.</I>
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Nothing can be deduced from the following: the magnitude of the difference
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of two
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<I>perflevels,</I>
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a
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<I>perflevel</I>
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value in isolation, or comparing
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<I>perflevels</I>
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from different servers.
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<P>
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<A NAME="lbAE"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="1">BadDrawable<DD>
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One or more values passed in
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<I>screen_specifiers</I>
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is not a valid drawable.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>SEE ALSO</H2>
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DBE,
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<I>XdbeAllocateBackBufferName(),</I>
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<I>XdbeBeginIdiom(),</I>
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<I>XdbeDeallocateBackBufferName(),</I>
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<I>XdbeEndIdiom(),</I>
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<I>XdbeFreeVisualInfo(),</I>
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<I>XdbeGetBackBufferAttributes(),</I>
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<I>XdbeQueryExtension(),</I>
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<I>XdbeSwapBuffers().</I>
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<P>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="2"><A HREF="#lbAB">NAME</A><DD>
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<DT id="3"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="4"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="5"><A HREF="#lbAE">ERRORS</A><DD>
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<DT id="6"><A HREF="#lbAF">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:00 GMT, March 31, 2021
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</BODY>
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</HTML>
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