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<HTML><HEAD><!-- This HTML file has been created by texi2html 1.54 from gdk.texi on 24 Febuary 1999 --><TITLE>GDK</TITLE></HEAD><BODY><H1>The General Drawing Kit</H1><H2>Version 1.0</H2><H2>May 1996</H2><ADDRESS>by Peter Mattis</ADDRESS><P><P><HR><P><H1><A NAME="SEC1" HREF="gdk_toc.html#TOC1">Copying</A></H1><P>GDK is <STRONG>free</STRONG>; this means that everyone is free to use it and freeto redestribute it on a free basis. GDK is not in the public domain; itis copyrighted and there are restrictions on its distribution, but theserestrictions are designed to permit everything that a good cooperatingcitizen would want to do. What is not allowed is to try to preventothers from further sharing any version of GDK that they might get fromyou.</P><P>Specifically, we want to make sure that you have the right to give awaycopies of GDK, that you receive source code or else can get it if youwant it, that you can change GDK or use pieces of it in new freeprograms, and that you know you can do these things.</P><P>To make sure that everyone has such rights, we have to forbid you todeprive anyone else of these rights. For example, if you distributecopies of GDK, you must give the recipients all the rights that youhave. You must make sure that they, too, receive or can get the sourcecode. And you must tell them their rights.</P><P>Also, for my own protection, we must make certain that everyone findsout that there is no warranty for GDK. If GDK is modified by someoneelse and passed on, we want their recipients to know that what they haveis not what we distributed, so that any problems introduced by otherswill no reflect on our reputation.</P><P>The precise conditions of the licenses for GDK are found in the GeneralPublic Licenses that accompanies it.</P><H1><A NAME="SEC2" HREF="gdk_toc.html#TOC2">What is GDK?</A></H1><P><A NAME="IDX1"></A></P><P>GDK is designed as a wrapper library that lies on top of Xlib. Itperforms many common and desired operations for a programmer insteadof the programmer having to explicitly ask for such functionality fromXlib directly. For example, GDK provides a common interface to bothregular and shared memory XImage types. By doing so, an applicationcan nearly transparently use the fastest image type available. GDKalso provides routines for determining the best available color depthand the best available visual which is not always the default visualfor a screen.</P><H1><A NAME="SEC3" HREF="gdk_toc.html#TOC3">Initialization and exit</A></H1><P><A NAME="IDX2"></A><A NAME="IDX3"></A></P><P>Initializing GDK is easy. Simply call <CODE>gdk_init</CODE> passing in the<VAR>argc</VAR> and <VAR>argv</VAR> parameters. Exit is similarly easy. Justcall <CODE>gdk_exit</CODE>.</P><P><DL><DT><U>Function:</U> void <B>gdk_init</B> <I>(int *<VAR>argc</VAR>, char ***<VAR>argv</VAR>)</I><DD><A NAME="IDX4"></A>Initializes the GDK library. The arguments <VAR>argc</VAR> and <VAR>argv</VAR>are scanned and any arguments that GDK recognizes are handled andremoved. The <VAR>argc</VAR> and <VAR>argv</VAR> parameters are the valuespassed to <CODE>main</CODE> upon program invocation.</DL></P><P><DL><DT><U>Function:</U> void <B>gdk_exit</B> <I>(int <VAR>errorcode</VAR>)</I><DD><A NAME="IDX5"></A>Exit GDK and perform any necessary cleanup. <CODE>gdk_exit</CODE> will callthe systems <CODE>exit</CODE> function passing <VAR>errorcode</VAR> as theparameter.</DL></P><PRE>intmain (int argc, char *argv[]){ /* Initialize GDK. */ gdk_init (&argc, &argv); /* Exit from GDK...this call will never return. */ gdk_exit (0); /* Keep compiler from issuing a warning */ return 0;}</PRE><H1><A NAME="SEC4" HREF="gdk_toc.html#TOC4">Event handling</A></H1><P><A NAME="IDX6"></A></P><P>Events are the means by which GDK lets the programmer know of userinteraction. An event is normally a button or key press or some otherindirect user action, such as a the mouse cursor entering or leaving awindow.</P><P>There exist only a few functions for getting events and eventinformation. These are <CODE>gdk_events_pending</CODE>,<CODE>gdk_event_get</CODE>, <CODE>gdk_events_record</CODE> and<CODE>gdk_events_playback</CODE>. The latter two functions are useful forautomatic testing of a software package and should normally not beneeded in a program.</P><P><DL><DT><U>Function:</U> gint <B>gdk_events_pending</B> <I>(void)</I><DD><A NAME="IDX7"></A>Returns the number of events pending on the event queue.</DL></P><P><DL><DT><U>Function:</U> gint <B>gdk_event_get</B> <I>(GdkEvent *<VAR>event</VAR>)</I><DD><A NAME="IDX8"></A>Return the next available event in the <VAR>event</VAR>structure. <CODE>gdk_event_get</CODE> will return <CODE>TRUE</CODE> on success and<CODE>FALSE</CODE> on failure. Success and failure is determined by whetheran event arrived before the timeout period expired.</DL></P><P><DL><DT><U>Function:</U> void <B>gdk_events_record</B> <I>(char *<VAR>filename</VAR>)</I><DD><A NAME="IDX9"></A>Turn on recording of events. User events and certain system events willbe saved in the file named by the variable <VAR>filename</VAR>. This streamof events can later be played back and "should" produce the sameresults as when the original events were handled. However, theprogrammer does need to be careful in that the state of the program mustbe the same when <CODE>gdk_events_record</CODE> is called and when<CODE>gdk_events_playback</CODE> is called. For this reason,<CODE>gdk_events_record</CODE> is normally not called directly, but is insteadinvoked indirectly by specifying the "-record" command line option.</DL></P><P><DL><DT><U>Function:</U> void <B>gdk_events_playback</B> <I>(char *<VAR>filename</VAR>)</I><DD><A NAME="IDX10"></A>Start playback of events from a file. (See the above description of<CODE>gdk_events_record</CODE>). Normally this function is not called directlybut is invoked by the "-playback" command line option.</DL></P><P><DL><DT><U>Function:</U> void <B>gdk_events_stop</B> <I>(void)</I><DD><A NAME="IDX11"></A>Stop recording and playback of events.</DL></P><PRE>voidhandle_event (){ GdkEvent event; if (gdk_event_get (&event)) { switch (event.type) { ... } }}</PRE><H1><A NAME="SEC5" HREF="gdk_toc.html#TOC5">Understanding and using visuals</A></H1><P><A NAME="IDX12"></A></P><H1><A NAME="SEC6" HREF="gdk_toc.html#TOC6">Creating and using windows</A></H1><P><A NAME="IDX13"></A></P><H1><A NAME="SEC7" HREF="gdk_toc.html#TOC7">Creating and modifying GCs</A></H1><P><A NAME="IDX14"></A><A NAME="IDX15"></A></P><H1><A NAME="SEC8" HREF="gdk_toc.html#TOC8">Creating pixmaps</A></H1><P><A NAME="IDX16"></A></P><H1><A NAME="SEC9" HREF="gdk_toc.html#TOC9">Creating images</A></H1><P><A NAME="IDX17"></A></P><H1><A NAME="SEC10" HREF="gdk_toc.html#TOC10">Specifying color</A></H1><P><A NAME="IDX18"></A></P><H1><A NAME="SEC11" HREF="gdk_toc.html#TOC11">Creating Fonts</A></H1><P><A NAME="IDX19"></A></P><H1><A NAME="SEC12" HREF="gdk_toc.html#TOC12">Drawing Commands</A></H1><P><A NAME="IDX20"></A></P><H1><A NAME="SEC13" HREF="gdk_toc.html#TOC13">Using extended devices</A></H1><P><A NAME="IDX21"></A><A NAME="IDX22"></A><A NAME="IDX23"></A></P><H1><A NAME="SEC14" HREF="gdk_toc.html#TOC14">Other stuff</A></H1><P><A NAME="IDX24"></A><A NAME="IDX25"></A><A NAME="IDX26"></A></P><H1><A NAME="SEC15" HREF="gdk_toc.html#TOC15">Using GDK</A></H1><P><A NAME="IDX27"></A></P><H1><A NAME="SEC16" HREF="gdk_toc.html#TOC16">Variable Index</A></H1><P><H2>g</H2><DIR><LI><A HREF="gdk.html#IDX8">gdk_event_get</A><LI><A HREF="gdk.html#IDX7">gdk_events_pending</A><LI><A HREF="gdk.html#IDX10">gdk_events_playback</A><LI><A HREF="gdk.html#IDX9">gdk_events_record</A><LI><A HREF="gdk.html#IDX11">gdk_events_stop</A><LI><A HREF="gdk.html#IDX5">gdk_exit</A><LI><A HREF="gdk.html#IDX4">gdk_init</A></DIR></P><H1><A NAME="SEC17" HREF="gdk_toc.html#TOC17">Concept Index</A></H1><P><H2>c</H2><DIR><LI><A HREF="gdk.html#IDX18">Color</A><LI><A HREF="gdk.html#IDX23">Controlling extended devices</A></DIR><H2>d</H2><DIR><LI><A HREF="gdk.html#IDX25">Debugging</A><LI><A HREF="gdk.html#IDX20">Drawing</A></DIR><H2>e</H2><DIR><LI><A HREF="gdk.html#IDX6">Events</A><LI><A HREF="gdk.html#IDX27">Examples</A><LI><A HREF="gdk.html#IDX3">Exit</A></DIR><H2>f</H2><DIR><LI><A HREF="gdk.html#IDX19">Fonts</A></DIR><H2>g</H2><DIR><LI><A HREF="gdk.html#IDX15">GC</A><LI><A HREF="gdk.html#IDX14">Graphics Contexts</A></DIR><H2>i</H2><DIR><LI><A HREF="gdk.html#IDX17">Images</A><LI><A HREF="gdk.html#IDX2">Initialization</A></DIR><H2>m</H2><DIR><LI><A HREF="gdk.html#IDX26">Miscellaneous</A></DIR><H2>o</H2><DIR><LI><A HREF="gdk.html#IDX1">Overview</A>, <A HREF="gdk.html#IDX21">Overview</A></DIR><H2>p</H2><DIR><LI><A HREF="gdk.html#IDX16">Pixmaps</A></DIR><H2>t</H2><DIR><LI><A HREF="gdk.html#IDX24">Timers</A></DIR><H2>u</H2><DIR><LI><A HREF="gdk.html#IDX22">Using extended device capabilities</A></DIR><H2>v</H2><DIR><LI><A HREF="gdk.html#IDX12">Visuals</A></DIR><H2>w</H2><DIR><LI><A HREF="gdk.html#IDX13">Windows</A></DIR></P><P><HR><P>This document was generated on 24 Febuary 1999 using the<A HREF="http://wwwcn.cern.ch/dci/texi2html/">texi2html</A>translator version 1.54.</P></BODY></HTML>⌨️ 快捷键说明
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