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<HTML><HEAD><TITLE>Xlib Programming Manual: XChangeProperty</TITLE></HEAD><BODY><H1 ALIGN=center>XChangeProperty</H1><H2>Syntax</H2><!.IN "Property" "changing"><!.IN "Property" "appending"><!.IN "Property" "prepending"><!.IN "Property" "replacing"><!.IN "Property" "format"><!.IN "Property" "type"><!.IN "XChangeProperty" "" "@DEF@"><CODE><PRE>XChangeProperty(<B>display</B>, <B>w</B>, <B>property</B>, <B>type</B>, <B>format</B>, <B>mode</B>, <B>data</B>, <B>nelements</B>) <A HREF="../display/opening.html#Display">Display</A> *<B>display</B>; Window <B>w</B>; <A HREF="properties-and-atoms.html">Atom</A> <B>property</B>, <B>type</B>; int <B>format</B>; int <B>mode</B>; unsigned char *<B>data</B>; int <B>nelements</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 whose property you want to change.<TR><TD> <B>property</B><TD> Specifies the property name.<TR><TD> <B>type</B><TD> Specifies the type of the property.The X server does not interpret the type but simplypasses it back to an application that later calls <B><A HREF="XGetWindowProperty.html">XGetWindowProperty()</A></B>.<TR><TD> <B>format</B><TD> Specifies whether the data should be viewed as a listof 8-bit, 16-bit, or 32-bit quantities.Possible values are 8, 16, and 32.This information allows the X server to correctly performbyte-swap operations as necessary.If the format is 16-bit or 32-bit,you must explicitly cast your data pointer to an (unsigned char *) in the callto <B><A HREF="XChangeProperty.html">XChangeProperty()</A></B>.<TR><TD> <B>mode</B><TD> Specifies the mode of the operation.You can pass<B>PropModeReplace</B>,<B>PropModePrepend</B>,or<B>PropModeAppend</B>.<TR><TD> <B>data</B><TD> Specifies the property data.<TR><TD> <B>nelements</B><TD> Specifies the number of elements of the specified data format.</TABLE><H2>Description</H2>The<B><A HREF="XChangeProperty.html">XChangeProperty()</A></B>function alters the property for the specified window andcauses the X server to generate a<B><A HREF="../events/client-communication/property-notify.html">PropertyNotify</A></B>event on that window.<B>XChangeProperty()</B>performs the following:<UL><P><LI>If mode is<B>PropModeReplace</B>,<B>XChangeProperty()</B>discards the previous property value and stores the new data.<P><LI>If mode is<B>PropModePrepend</B>or<B>PropModeAppend</B>,<B>XChangeProperty()</B>inserts the specified data before the beginning of the existing dataor onto the end of the existing data, respectively.The type and format must match the existing property value,or a<B>BadMatch</B>error results.If the property is undefined, it is treated as defined with the correct type andformat with zero-length data.</UL>If the specified format is 8, the property data must be a<B>char</B>array.If the specified format is 16, the property data must be a<B>short</B>array.If the specified format is 32, the property data must be a<B>long</B>array.<P>The lifetime of a property is not tied to the storing client.Properties remain until explicitly deleted, until the window is destroyed,or until the server resets.For a discussion of what happens when the connection to the X server is closed,see section "<A HREF="../display/close-operation.html">X Server Connection Close Operations</A>".The maximum size of a property is server dependent and can vary dynamicallydepending on the amount of memory the server has available.(If there is insufficient space, a<B>BadAlloc</B>error results.)<P><B>XChangeProperty()</B>can generate<B>BadAlloc</B> ,<B>BadAtom</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>BadAtom</B><TD> A value for an Atom argument does not name a defined Atom.<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="XDeleteProperty.html">XDeleteProperty()</A></B>,<B><A HREF="XGetWindowProperty.html">XGetWindowProperty()</A></B>,<B><A HREF="XListProperties.html">XListProperties()</A></B>,<B><A HREF="XRotateWindowProperties.html">XRotateWindowProperties()</A></B>,"<A HREF="obtain-properties.html">Obtaining and Changing Window Properties</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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