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<HTML><HEAD><TITLE>Xlib Programming Manual: XTextExtents</TITLE></HEAD><BODY><H1 ALIGN=center>XTextExtents</H1><H2>Syntax</H2><!.IN "XTextExtents" "" "@DEF@"><CODE><PRE>XTextExtents(<B>font_struct</B>, <B>string</B>, <B>nchars</B>, <B>direction_return</B>, <B>font_ascent_return</B>, <B>font_descent_return</B>, <B>overall_return</B>) <A HREF="./#XFontStruct">XFontStruct</A> *<B>font_struct</B>; char *<B>string</B>; int <B>nchars</B>; int *<B>direction_return</B>; int *<B>font_ascent_return</B>, *<B>font_descent_return</B>; <A HREF="./#XCharStruct">XCharStruct</A> *<B>overall_return</B>;</PRE></CODE><H2>Arguments</H2><TABLE><TR><TD> <B>font_struct</B><TD> Specifies the <A HREF="./#XFontStruct">XFontStruct</A> structure.<TR><TD> <B>string</B><TD> Specifies the character string.<TR><TD> <B>nchars</B><TD> Specifies the number of characters in the character string.<TR><TD> <B>direction_return</B><TD> Returns the value of the direction hint(<B>FontLeftToRight</B>or<B>FontRightToLeft</B>).<TR><TD> <B>font_ascent_return</B><TD> Returns the font ascent.<TR><TD> <B>font_descent_return</B><TD> Returns the font descent.<TR><TD> <B>overall_return</B><TD> Returns the overall size in the specified<A HREF="./#XCharStruct">XCharStruct</A> structure.</TABLE><H2>Description</H2>The<B>XTextExtents()</B>functionperforms the size computation locally and, thereby,avoid the round-trip overhead of<B><A HREF="XQueryTextExtents.html">XQueryTextExtents()</A></B>and<B><A HREF="XQueryTextExtents16.html">XQueryTextExtents16()</A></B>.The function returns an<A HREF="./#XCharStruct">XCharStruct</A>structure, whose members are set to the values as follows.<P>The ascent member is set to the maximum of the ascent metrics of allcharacters in the string.The descent member is set to the maximum of the descent metrics.The width member is set to the sum of the character-width metrics of allcharacters in the string.For each character in the string,let W be the sum of the character-width metrics of all characters preceding it in the string.Let L be the left-side-bearing metric of the character plus W.Let R be the right-side-bearing metric of the character plus W.The lbearing member is set to the minimum L of all characters in the string.The rbearing member is set to the maximum R.<P>For fonts defined with linear indexing rather than 2-byte matrix indexing,each <A HREF="./#XChar2b">XChar2b</A> structure is interpreted as a 16-bit number with byte1 as the most-significant byte.If the font has no defined default character,undefined characters in the string are taken to have all zero metrics.<H2>See also</H2><B><A HREF="XQueryTextExtents.html">XQueryTextExtents()</A></B>,<B><A HREF="XQueryTextExtents16.html">XQueryTextExtents16()</A></B>,<B><A HREF="XTextExtents16.html">XTextExtents16()</A></B>,"<A HREF="computing-logical-extent.html">Computing Logical Extents</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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