📄 qdatasource.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- /home/reggie/tmp/qt-3.0-reggie-5401/qt-x11-commercial-3.0.5/src/kernel/qasyncio.cpp:131 --><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>QDataSource Class</title><style type="text/css"><!--h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm; }a:link { color: #004faf; text-decoration: none }a:visited { color: #672967; text-decoration: none }body { background: #ffffff; color: black; }--></style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr bgcolor="#E5E5E5"><td valign=center> <a href="index.html"><font color="#004faf">Home</font></a> | <a href="classes.html"><font color="#004faf">All Classes</font></a> | <a href="mainclasses.html"><font color="#004faf">Main Classes</font></a> | <a href="annotated.html"><font color="#004faf">Annotated</font></a> | <a href="groups.html"><font color="#004faf">Grouped Classes</font></a> | <a href="functions.html"><font color="#004faf">Functions</font></a></td><td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QDataSource Class Reference<br><small>[obsolete]</small></h1><p>The QDataSource class is an asynchronous producer of data.<a href="#details">More...</a><p><tt>#include <<a href="qasyncio-h.html">qasyncio.h</a>></tt><p>Inherits <a href="qasyncio.html">QAsyncIO</a>.<p>Inherited by <a href="qiodevicesource.html">QIODeviceSource</a>.<p><a href="qdatasource-members.html">List of all member functions.</a><h2>Public Members</h2><ul><li><div class=fn>virtual int <a href="#readyToSend"><b>readyToSend</b></a> () = 0</div></li><li><div class=fn>virtual void <a href="#sendTo"><b>sendTo</b></a> ( QDataSink *, int count ) = 0</div></li><li><div class=fn>void <a href="#maybeReady"><b>maybeReady</b></a> ()</div></li><li><div class=fn>virtual bool <a href="#rewindable"><b>rewindable</b></a> () const</div></li><li><div class=fn>virtual void <a href="#enableRewind"><b>enableRewind</b></a> ( bool on )</div></li><li><div class=fn>virtual void <a href="#rewind"><b>rewind</b></a> ()</div></li></ul><hr><a name="details"></a><h2>Detailed Description</h2><b>This class is obsolete.</b> It is provided to keep old source working. We strongly advise against using it in new code.<p> The QDataSource class is an asynchronous producer of data.<p> A data source is an object which provides data from some source in anasynchronous manner. This means that at some time not determined bythe data source, blocks of data will be taken from it for processing.The data source is able to limit the maximum size of such blocks whichit is currently able to provide.<p> <p>See also <a href="qasyncio.html">QAsyncIO</a>, <a href="qdatasink.html">QDataSink</a> and <a href="qdatapump.html">QDataPump</a>.<hr><h2>Member Function Documentation</h2><h3 class=fn>void <a name="enableRewind"></a>QDataSource::enableRewind ( bool on )<tt> [virtual]</tt></h3>If this function is called with <em>on</em> set to TRUE, and <a href="#rewindable">rewindable</a>()is TRUE, then the data source must take measures to allow the <a href="#rewind">rewind</a>()function to subsequently operate as described. If rewindable() is FALSE,the function should call <a href="#enableRewind">QDataSource::enableRewind</a>(), which aborts witha <a href="qapplication.html#qFatal">qFatal</a>() error.<p> For example, a network connection may choose to use a disk cacheof input only if rewinding is enabled before the first buffer-full ofdata is discarded, returning FALSE in rewindable() if that first bufferis discarded.<p>Reimplemented in <a href="qiodevicesource.html#enableRewind">QIODeviceSource</a>.<h3 class=fn>void <a name="maybeReady"></a>QDataSource::maybeReady ()</h3>This should be called whenever <a href="#readyToSend">readyToSend</a>() might have become non-zero.It is merely calls <a href="qasyncio.html#ready">QAsyncIO::ready</a>() if readyToSend() is non-zero.<h3 class=fn>int <a name="readyToSend"></a>QDataSource::readyToSend ()<tt> [pure virtual]</tt></h3><p> The data source should return a value indicating how much data it is readyto provide. This may be 0. If the data source knows it will never beable to provide any more data (until after a <a href="#rewind">rewind</a>()), it may return -1.<p>Reimplemented in <a href="qiodevicesource.html#readyToSend">QIODeviceSource</a>.<h3 class=fn>void <a name="rewind"></a>QDataSource::rewind ()<tt> [virtual]</tt></h3>This function rewinds the data source. This may only be called if<a href="#enableRewind">enableRewind</a>(TRUE) has been previously called.<p>Reimplemented in <a href="qiodevicesource.html#rewind">QIODeviceSource</a>.<h3 class=fn>bool <a name="rewindable"></a>QDataSource::rewindable () const<tt> [virtual]</tt></h3>This function should return TRUE if the data source can be rewound.<p> The default returns FALSE.<p>Reimplemented in <a href="qiodevicesource.html#rewindable">QIODeviceSource</a>.<h3 class=fn>void <a name="sendTo"></a>QDataSource::sendTo ( <a href="qdatasink.html">QDataSink</a> *, int count )<tt> [pure virtual]</tt></h3><p> This function is called to extract data from the source, by sendingit to the given data sink. The <em>count</em> will be no more than the amountindicated by the most recent call to <a href="#readyToSend">readyToSend</a>(). The source mustuse all the provided data, and the sink will be prepared to accept atleast this much data.<p>Reimplemented in <a href="qiodevicesource.html#sendTo">QIODeviceSource</a>.<!-- eof --><hr><p>This file is part of the <a href="index.html">Qt toolkit</a>.Copyright © 1995-2002<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center><table width=100% cellspacing=0 border=0><tr><td>Copyright © 2002 <a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a><td align=right><div align=right>Qt version 3.0.5</div></table></div></address></body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -