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<HTML><HEAD><TITLE>Xlib Programming Manual: XCreateColormap</TITLE></HEAD><BODY><H1 ALIGN=center>XCreateColormap</H1><H2>Syntax</H2><!.IN "XCreateColormap" "" "@DEF@"><CODE><PRE><A HREF="./#colormap">Colormap</A> XCreateColormap(<B>display</B>, <B>w</B>, <B>visual</B>, <B>alloc</B>) <A HREF="../display/opening.html#Display">Display</A> *<B>display</B>; Window <B>w</B>; <A HREF="../window/visual-types.html#Visual">Visual</A> *<B>visual</B>; int <B>alloc</B>;</PRE></CODE><H2>Arguments</H2><TABLE><TR><TD> <B>display</B><TD> Specifies the connection to the X server.<TR><TD> <B>w</B><TD> Specifies the window on whose screen you want to create a colormap.<TR><TD> <B>visual</B><TD> Specifies a visual type supported on the screen.If the visual type is not one supported by the screen, a<B>BadMatch</B>error results.<TR><TD> <B>alloc</B><TD> Specifies the colormap entries to be allocated.You can pass <B>AllocNone</B>or <B>AllocAll</B>.</TABLE><H2>Description</H2>The<B>XCreateColormap()</B>function creates a colormap of the specified visual type for the screen on which the specified window resides and returns the colormap ID associated with it.Note that the specified window is only used to determine the screen.<P>The initial values of the colormap entries are undefined for the visual classes<B><A HREF="../window/visual-types.html">GrayScale</A></B>,<B><A HREF="../window/visual-types.html">PseudoColor</A></B>,and<B><A HREF="../window/visual-types.html">DirectColor</A></B> .For<B><A HREF="../window/visual-types.html">StaticGray</A></B>,<B><A HREF="../window/visual-types.html">StaticColor</A></B>,and<B><A HREF="../window/visual-types.html">TrueColor</A></B>,the entries have defined values,but those values are specific to the visual and are not defined by X.For<B><A HREF="../window/visual-types.html">StaticGray</A></B>,<B><A HREF="../window/visual-types.html">StaticColor</A></B>,and<B><A HREF="../window/visual-types.html">TrueColor</A></B>,alloc must be<B>AllocNone</B>,or a<B>BadMatch</B>error results.For the other visual classes,if alloc is<B>AllocNone</B>,the colormap initially has no allocated entries,and clients can allocate them.For information about the visual types,see "<A HREF="../window/visual-types.html">Visual Types</A>".<P>If alloc is<B>AllocAll</B>,the entire colormap is allocated writable.The initial values of all allocated entries are undefined.For<B><A HREF="../window/visual-types.html">GrayScale</A></B>and<B><A HREF="../window/visual-types.html">PseudoColor</A></B>,the effect is as if an<B><A HREF="XAllocColorCells.html">XAllocColorCells()</A></B>call returned all pixel values from zero to N - 1,where N is the colormap entries value in the specified visual.For<B><A HREF="../window/visual-types.html">DirectColor</A></B>,the effect is as if an<B><A HREF="XAllocColorPlanes.html">XAllocColorPlanes()</A></B>call returned a pixel value of zero and red_mask, green_mask, and blue_mask values containing the same bits as the correspondingmasks in the specified visual.However, in all cases,none of these entries can be freed by using<B><A HREF="XFreeColors.html">XFreeColors()</A></B>.<P><B>XCreateColormap()</B>can generate<B>BadAlloc</B>,<B>BadMatch</B>,<B>BadValue</B>,and<B>BadWindow</B> errors.<H2>Diagnostics</H2><TABLE><TR><TD><B>BadAlloc</B><TD> The server failed to allocate the requested source or server memory.<TR><TD><B>BadMatch</B><TD>An<B><A HREF="../window/create.html#InputClass">InputOnly</A></B>window is used as a Drawable.<TR><TD><B>BadMatch</B><TD>Some argument or pair of arguments has the correct type and range but fails to match in some other way required by the request. <TR><TD><B>BadPixmap</B><TD> A value for a Pixmap argument does not name a defined Pixmap.<TR><TD><B>BadValue</B><TD> Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error.<TR><TD><B>BadWindow</B><TD>A value for a Window argument does not name a defined Window.</TABLE><H2>See also</H2><B><A HREF="XAllocColor.html">XAllocColor()</A></B>,<B><A HREF="../window/XChangeWindowAttributes.html">XChangeWindowAttributes()</A></B>,<B><A HREF="XCopyColormapAndFree.html">XCopyColormapAndFree()</A></B>,<B><A HREF="../window/XCreateWindow.html">XCreateWindow()</A></B>,<B><A HREF="XFreeColormap.html">XFreeColormap()</A></B>,<B><A HREF="XQueryColor.html">XQueryColor()</A></B>,<B><A HREF="XStoreColors.html">XStoreColors()</A></B>,"<A HREF="colormap.html">Creating, Copying, and Destroying Colormaps</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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