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<HTML><HEAD><TITLE>Xlib Programming Manual: XAllocColor</TITLE></HEAD><BODY><H1 ALIGN=center>XAllocColor</H1><H2>Syntax</H2><!.IN "Allocation" "read-only colormap cells"><!.IN "Read-only colormap cells" "allocating"><!.IN "Color" "allocation"><!.IN "XAllocColor" "" "@DEF@"><CODE><PRE><B><A HREF="../introduction/errors.html#Status">Status</A></B> XAllocColor(<B>display</B>, <B>colormap</B>, <B>screen_in_out</B>) <A HREF="../display/opening.html#Display">Display</A> *<B>display</B>; <A HREF="./#colormap">Colormap</A> <B>colormap</B>; <A HREF="structures.html">XColor</A> *<B>screen_in_out</B>;</PRE></CODE><H2>Arguments</H2><TABLE><TR><TD> <B>display</B><TD> Specifies the connection to the X server.<TR><TD> <B>colormap</B><TD> Specifies the colormap.<TR><TD> <B>screen_in_out</B><TD> Specifies and returns the values actually used in the colormap.</TABLE><H2>Description</H2>The<B>XAllocColor()</B>function allocates a read-only colormap entry corresponding to the closestRGB value supported by the hardware.<B>XAllocColor()</B>returns the pixel value of the color closest to the specifiedRGB elements supported by the hardwareand returns the RGB value actually used.The corresponding colormap cell is read-only.In addition,<B>XAllocColor()</B>returns nonzero if it succeeded or zero if it failed.<!.IN "Color map"><!.IN "Color" "allocation"><!.IN "Allocation" "colormap"><!.IN "read-only colormap cells">Multiple clients that request the same effective RGB value can be assignedthe same read-only entry, thus allowing entries to be shared.When the last client deallocates a shared cell, it is deallocated.<B>XAllocColor()</B>does not use or affect the flags in the<A HREF="structures.html">XColor</A>structure.<P><B>XAllocColor()</B>can generate a<B>BadColor</B> error.<H2>Diagnostics</H2><TABLE><TR><TD><B>BadColor</B><TD> A value for a Colormap argument does not name a defined Colormap.</TABLE><H2>See also</H2><B><A HREF="XAllocColorCells.html">XAllocColorCells()</A></B>,<B><A HREF="XAllocColorPlanes.html">XAllocColorPlanes()</A></B>,<B><A HREF="XAllocNamedColor.html">XAllocNamedColor()</A></B>,<B><A HREF="XCreateColormap.html">XCreateColormap()</A></B>,<B><A HREF="XFreeColors.html">XFreeColors()</A></B>,<B><A HREF="XQueryColor.html">XQueryColor()</A></B>,<B><A HREF="XStoreColors.html">XStoreColors()</A></B>,"<A HREF="cell.html">Allocating and Freeing Color Cells</A>".<HR><ADDRESS><A HREF="http://tronche.com/">Christophe Tronche</A>, <A HREF="mailto:ch.tronche@computer.org">ch.tronche@computer.org</A></ADDRESS></BODY></HTML>⌨️ 快捷键说明
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