561 lines
17 KiB
XML
561 lines
17 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
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<book id="tog-cup">
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<bookinfo>
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<title>Colormap Utilization Policy and Extension</title>
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<subtitle>X Project Team Standard</subtitle>
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<releaseinfo>Version 1.0</releaseinfo>
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<authorgroup>
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<author>
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<firstname>Kaleb</firstname>
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<othername>S.</othername>
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<surname>Keithley</surname>
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<affiliation><orgname>The Open Group</orgname></affiliation>
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</author>
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</authorgroup>
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<corpname>X Consortium Standard</corpname>
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<copyright><year>1986-1997</year><holder>The Open Group</holder></copyright>
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<affiliation><orgname>X Consortium</orgname></affiliation>
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<productnumber>X Version 11, Release 6.8</productnumber>
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<legalnotice>
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<para>
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this
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software and associated documentation files (the Software), to use the
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Software
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without restriction, including, without limitation, the rights to copy,
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modify, merge,
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publish, distribute and sublicense the Software, to make, have made,
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license and
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distribute derivative works thereof, and to permit persons to whom the
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Software is
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furnished to do so, subject to the following conditions:
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</para>
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<para>
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The above copyright notice and the following permission notice shall be
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included in all copies of the Software:
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</para>
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<para>
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE WARRANTIES
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OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-
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INFRINGEMENT. IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY
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CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF, OR IN
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CONNNECTION WITH THE SOFTWARE OR THE USE OF OTHER DEALINGS IN
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THE SOFTWARE.
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</para>
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<para>
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Except as contained in this notice, the name of The Open Group shall not be
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used in
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advertising or otherwise to promote the use or other dealings in this
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Software without prior written authorization from The Open Group.
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</para>
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<para>
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X Window System is a trademark of The Open Group.
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</para>
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</legalnotice>
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</bookinfo>
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<chapter id="Overview">
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<title>Overview</title>
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<para>
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This extension has three purposes: a) to provide mechanism for a special
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application (a colormap manager) to discover any special colormap
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requirements, e.g. the colormap entries that are nominally reserved for
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desktop colors in the MS-Windows environment and initialize the default
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colormap so that it can be more easily shared; and b) to encourage colormap
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sharing and reduce colormap flashing on low-end 8-bit frame buffers by
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providing a policy for sharing; and c) when colormaps aren't shared,
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define a behavior in the X server color allocation scheme to reduce
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colormap flashing.
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</para>
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<para>
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To encourage colormap sharing and accomodate special colormap requirements
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two new protocols are defined: the first provides a way to query the
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server for a list of reserved colormap entries, and the second is a way
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to initialize read-only (shareable) colormap entries at specific locations
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in a colormap.
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</para>
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<para>
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To minimize colormap flashing when the root window's default visual is one
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of GrayScale, PseudoColor, or DirectColor, and a private colormap for the
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default visual is being used, a minor (but compatible) change to the
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server implementation of the AllocColor and AllocNamedColor requests is
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required. Where the core protocol says nothing about the pixel values
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returned, when this extension is in effect, the AllocColor and AllocNamedColor
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requests will first look for a matching color in the default colormap, and,
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if a match is found and the same cell in the private colormap has not
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already been allocated, the color will be allocated in the private colormap
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at the same locaton as in the default colormap (instead of in the first
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available location.)
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</para>
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</chapter>
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<chapter id="Requests">
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<title>Requests</title>
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<para>
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<function>QueryVersion</function>
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</para>
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<informaltable frame="none">
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<tgroup cols='1' align='left'>
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<colspec colname='c1' colsep="0" colwidth="1*"/>
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<tbody>
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<row rowsep="0">
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<entry>
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client_major_version: CARD16
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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client_minor_version: CARD16
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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=>
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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server_major_version: CARD16
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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server_minor_version: CARD16
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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If supplied, the client_major_version and client_minor_version indicate
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what version of the protocol the client wants the server to implement.
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The server version numbers returned indicate the protocol this extension
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actually supports. This might not equal the version sent by the client.
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An implementation can (but need not) support more than one version
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simultaneously. The server_major_version and the server_minor_version
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are a mechanism to support future revisions of the TOG-CUP protocol that
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may be necessary. In general, the major version would increment for
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incompatible changes, and the minor version would increment for small
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upward-compatible changes. Servers that support the protocol defined in
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this document will return a server_major_version of one (1), and a
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server_minor_version of zero (0).
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</para>
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<para>
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<function>GetReservedColormapEntries</function>
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</para>
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<informaltable frame="none">
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<tgroup cols='1' align='left'>
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<colspec colname='c1' colsep="0" colwidth="1*"/>
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<tbody>
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<row rowsep="0">
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<entry>
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screen: CARD32
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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=>
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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entries: LISTofCOLORITEM
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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This request returns a list of colormap entries (pixels) that are reserved
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by the system, e.g. MS-Windows reserved desktop colors. This list will, at a
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minimum, contain entries for the BlackPixel and WhitePixel of the specified
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screen. The do-red, do-green, and do-blue elements of the COLORITEMs are
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unused in this reply.
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</para>
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<para>
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Rationale: There are colormap entries (pixels) that, e.g., MS-Windows
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desktop reserves as desktop colors, that should not be altered. If they
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are altered then X programs will cause colormap flashing between X and
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MS-Windows applications running/displaying on the same desktop.
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</para>
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<para>
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<function>StoreColors</function>
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</para>
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<informaltable frame="none">
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<tgroup cols='1' align='left'>
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<colspec colname='c1' colsep="0" colwidth="1*"/>
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<tbody>
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<row rowsep="0">
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<entry>
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cmap: COLORMAP
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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items: LISTofCOLORITEM
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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=>
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</entry>
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</row>
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<row rowsep="0">
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<entry>
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items: LISTofCOLORITEM
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</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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<para>
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This request changes the colormap entries of the specified pixels. The
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colormap entries are allocated as if by an AllocColor request. The do-red,
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do-green, and do-blue elements of the COLORITEMs are unused in this request.
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A boolean alloc-ok element (a bit) is returned indicating whether the
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particular pixel was successfully allocated or not. If successfully
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allocated the RGB and pixel are returned.
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</para>
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<para>
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A Value error is generated if a pixel is not a valid index into cmap. A
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BadMatch error is generated if if cmap does not belong to a GrayScale,
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PseudoColor, or DirectColor visual.
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</para>
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</chapter>
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<chapter id="Events_and_Errors">
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<title>Events and Errors</title>
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<para>
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No new events or errors are defined by this extension.
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</para>
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</chapter>
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<chapter id="Changes_to_existing_protocol_">
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<title>Changes to existing protocol.</title>
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<para>
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None.
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</para>
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</chapter>
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<chapter id="Encoding">
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<title>Encoding</title>
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<para>
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The name of this extension is "TOG-CUP".
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</para>
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<para>
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The conventions used here are the same as those for the core X11
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Protocol Encoding.
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</para>
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<literallayout class="monospaced">
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<function>QueryVersion</function>
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1 CARD8 opcode
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1 0 TOG-CUP opcode
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2 2 request length
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2 CARD16 client_major_version
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2 CARD16 client_minor_version
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=>
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1 1 reply
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1 unused
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2 CARD16 sequence number
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4 0 length
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2 CARD16 server_major_version
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2 CARD16 server_minor_number
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20 unused
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</literallayout>
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<literallayout class="monospaced">
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<function>GetReservedColormapEntries</function>
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1 CARD8 opcode
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1 1 TOG-CUP opcode
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2 2 request length
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4 CARD32 screen
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=>
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1 1 reply
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1 unused
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2 CARD16 sequence number
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4 3n length
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24 unused
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12n LISTofCOLORITEM items
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</literallayout>
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<literallayout class="monospaced">
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<function>StoreColors</function>
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1 CARD8 opcode
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1 2 TOG-CUP opcode
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2 2+3n request length
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4 COLORMAP cmap
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12n LISTofCOLORITEM items
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=>
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1 1 reply
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1 unused
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2 CARD16 sequence number
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4 3n length
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24 unused
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12n LISTofCOLORITEM items
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</literallayout>
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<para>
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(The definition of COLORITEM here is only for the purpose of defining the
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additional alloc-ok member in the CUPStoreColors reply.)
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</para>
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<literallayout class="monospaced">
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COLORITEM
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4 CARD32 pixel
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2 CARD16 red
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2 CARD16 green
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2 CARD16 blue
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1 alloc-ok
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#x07 unused
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#x08 alloc-ok (1 is True, 0 is False)
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#xF0 unused
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1 unused
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</literallayout>
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</chapter>
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<chapter id="C_Language_Binding">
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<title>C Language Binding</title>
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<para>
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The C functions provide direct access to the protocol and add no additional
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semantics. For complete details on the effects of these functions, refer
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to the appropriate protocol request, which can be derived by deleting XCup
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at the start of the function. All functions that have return type Status
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will return nonzero for success and zero for failure.
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</para>
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<para>
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The include file for this extension is
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<function><X11/extensions/Xcup.h></function>.
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</para>
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<funcsynopsis>
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<funcprototype>
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<funcdef>Status <function> XCupQueryVersion</function></funcdef>
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<paramdef>Display*<parameter> display</parameter></paramdef>
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<paramdef>int*<parameter> major_version_return</parameter></paramdef>
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<paramdef>int*<parameter> minor_version_return</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>display</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the connection to the X server.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>major_version_return</emphasis>
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</term>
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<listitem>
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<para>
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Returns the major version supported by the server.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>minor_version_return</emphasis>
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</term>
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<listitem>
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<para>
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Returns the minor version supported by the server.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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XCupQueryVersions sets major_version_return and minor_version_return to
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the major and minor TOG-CUP protocol version supported by the server. If
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the TOG-CUP library is compatible with the version returned by the server,
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it returns nonzero. If dpy does not support the TOG-CUP extension, or if
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there was an error during communication with the server, or if the server
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and library protocol versions are incompatible, it returns zero. No other
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XCup functions may be called before this function. If a client violates
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this rule, the effects of all subsequent XCup calls that it makes are
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undefined.
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</para>
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<para>
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To get the list of reserved colormap entries, use
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XCupGetReservedColormapEntries.
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</para>
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<funcsynopsis>
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<funcprototype>
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<funcdef>Status <function> XCupGetReservedColormapEntries</function></funcdef>
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<paramdef>Display*<parameter> display</parameter></paramdef>
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<paramdef>int<parameter> screen</parameter></paramdef>
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<paramdef>XColor**<parameter> colors_out</parameter></paramdef>
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<paramdef>int*<parameter> ncolors</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>display</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the connection to the X server.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>colors_out</emphasis>
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</term>
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<listitem>
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<para>
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Returns the values reserved by the server.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>ncolors</emphasis>
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</term>
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<listitem>
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<para>
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Returns the number of items in colors_out.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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The XCupGetReservedColormapEntries function gets system specific colormap
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entries. E.g. the MS-Windows desktop uses N colormap entries at the beginning
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(0..N) and end (256-N..255) of the colormap. Use XFree to free colors_out.
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</para>
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<para>
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To allocate one or more read-only color cells with RGB values, use
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XCupStoreColors.
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</para>
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<funcsynopsis>
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<funcprototype>
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<funcdef>Status <function> XCupStoreColors</function></funcdef>
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<paramdef>Display*<parameter> display</parameter></paramdef>
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<paramdef>Colormap<parameter> colormap</parameter></paramdef>
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<paramdef>XColor*<parameter> colors_in_out</parameter></paramdef>
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<paramdef>int<parameter> ncolors</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<variablelist>
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<varlistentry>
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<term>
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<emphasis remap='I'>display</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the connection to the X server.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>colormap</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the colormap.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>colors_in_out</emphasis>
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</term>
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<listitem>
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<para>
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Specifies and returns the values actually used in the colormap.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<emphasis remap='I'>ncolors</emphasis>
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</term>
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<listitem>
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<para>
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Specifies the number of items in colors_in_out.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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The XCupStoreColors function changes the colormap entries of the pixel
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values specified in the pixel members of the XColor structures. The colormap
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entries are allocated as if an AllocColor had been used instead, i.e. the
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colors are read-only (shareable). XCupStoreColors returns the number of
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colors that were successfully allocated in the colormap.
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</para>
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</chapter>
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|
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<chapter id="Using_the_TOG_CUP_extension_and_Colormap_Utilization_Policy">
|
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<title>Using the TOG-CUP extension and Colormap Utilization Policy</title>
|
|
<para>
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The X server preallocates any hardware or desktop special colors in the
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default colormap; e.g. UNIX X servers preallocate Black and White pixels.
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PC X servers should also preallocate the MS-Windows desktop colors. (Note
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to implementors: in the Sample Implementation special colors are allocated
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in the default colormap in cfbCreateDefColormap for dumb memory framebuffers.)
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</para>
|
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<para>
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To minimize colormap flash an application which installs its own private
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colormap should query the special colors by calling
|
|
XCupGetReservedColormapEntries, and can then store those entries (in the
|
|
proper location) in its private colormap using XCupStoreColors.
|
|
</para>
|
|
|
|
<para>
|
|
Applications which allocate many colors in a screen's default colormap, e.g.
|
|
a color-cube or a gray-ramp, should allocate them with XCupStoreColors. By
|
|
using XCupStoreColors the colors will be allocated sharable (read-only) and
|
|
any other application which allocates the same color will share that color
|
|
cell.
|
|
</para>
|
|
</chapter>
|
|
|
|
</book>
|