126 lines
3.9 KiB
Groff
126 lines
3.9 KiB
Groff
.\" Copyright (c) 1995 Hewlett-Packard Company
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.\"
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.\" Permission is hereby granted, free of charge, to any person obtaining a
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.\" copy of this software and associated documentation files (the "Software"),
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.\" to deal in the Software without restriction, including without limitation
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.\" the rights to use, copy, modify, merge, publish, distribute, sublicense,
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.\" and/or sell copies of the Software, and to permit persons to whom the
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.\" Software furnished to do so, subject to the following conditions:
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.\"
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.\" The above copyright notice and this permission notice shall be included in
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.\" all copies or substantial portions of the Software.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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.\" IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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.\" FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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.\" HEWLETT-PACKARD COMPANY BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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.\" WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
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.\" OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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.\" SOFTWARE.
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.\"
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.\" Except as contained in this notice, the name of the Hewlett-Packard Company shall not
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.\" be used in advertising or otherwise to promote the sale, use or other
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.\" dealing in this Software without prior written authorization from the
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.\" Hewlett-Packard Company.
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.\"
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.TH XdbeGetVisualInfo __libmansuffix__ __xorgversion__ "X FUNCTIONS"
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.SH NAME
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XdbeGetVisualInfo - Get dbe Visual Informations
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.SH SYNOPSIS
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\&#include <X11/extensions/Xdbe.h>
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XdbeScreenVisualInfo *XdbeGetVisualInfo(
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Display *dpy,
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Drawable *screen_specifiers,
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int *num_screens)
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.SH DESCRIPTION
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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
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specifies how many elements there are
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in the
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.I screen_specifiers
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list. Each drawable in
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.I screen_specifiers
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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
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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
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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
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structures of length
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.I num_screens.
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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
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list, unless
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.I num_screens
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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
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structure has the following fields:
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int count
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XdbeVisualInfo *visinfo
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.I count
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specifies the number of items in
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.I visinfo.
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.I visinfo
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specifies a list of visuals, depths, and performance hints for this screen.
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The
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.I XdbeVisualInfo
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structure has the following fields:
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VisualID visual
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int depth
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int perflevel
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.I visual
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specifies one visual ID that supports double-buffering.
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.I depth
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specifies the depth of the visual.
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.I perflevel
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is a performance hint.
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The only operation defined on a
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.I perflevel
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is comparison to a
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.I perflevel
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of another visual on the same screen. The visual having the higher
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.I perflevel
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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.
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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,
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a
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.I perflevel
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value in isolation, or comparing
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.I perflevels
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from different servers.
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.SH ERRORS
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.IP BadDrawable
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One or more values passed in
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.I screen_specifiers
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is not a valid drawable.
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.SH SEE ALSO
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DBE,
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.I XdbeAllocateBackBufferName(),
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.I XdbeBeginIdiom(),
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.I XdbeDeallocateBackBufferName(),
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.I XdbeEndIdiom(),
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.I XdbeFreeVisualInfo(),
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.I XdbeGetBackBufferAttributes(),
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.I XdbeQueryExtension(),
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.I XdbeSwapBuffers().
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