|
|
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|
|
|
|
<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/tutorial2.doc:969 -->
|
|
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
|
|
|
|
<title>File Handling</title>
|
|
|
|
|
<style type="text/css"><!--
|
|
|
|
|
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>File Handling</h1>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
<p> (Extracts from <tt>chartform_files.cpp</tt>.)
|
|
|
|
|
<p> <h2> Reading Chart Data
|
|
|
|
|
</h2>
|
|
|
|
|
<a name="1"></a><p>
|
|
|
|
|
|
|
|
|
|
<pre> void ChartForm::load( const <a href="tqstring.html">TQString</a>& filename )
|
|
|
|
|
{
|
|
|
|
|
<a href="ntqfile.html">TQFile</a> file( filename );
|
|
|
|
|
if ( !file.<a href="ntqfile.html#open">open</a>( <a href="ntqfile.html#open">IO_ReadOnly</a> ) ) {
|
|
|
|
|
<a href="ntqmainwindow.html#statusBar">statusBar</a>()->message( TQString( "Failed to load \'%1\'" ).
|
|
|
|
|
arg( filename ), 2000 );
|
|
|
|
|
return;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
init(); // Make sure we have colours
|
|
|
|
|
m_filename = filename;
|
|
|
|
|
<a href="tqtextstream.html">TQTextStream</a> ts( &file );
|
|
|
|
|
Element element;
|
|
|
|
|
int errors = 0;
|
|
|
|
|
int i = 0;
|
|
|
|
|
<a name="x2592"></a> while ( !ts.<a href="tqtextstream.html#eof">eof</a>() ) {
|
|
|
|
|
ts >> element;
|
|
|
|
|
if ( element.isValid() )
|
|
|
|
|
m_elements[i++] = element;
|
|
|
|
|
</pre><pre> <a name="x2590"></a> file.<a href="ntqfile.html#close">close</a>();
|
|
|
|
|
</pre>
|
|
|
|
|
<p> <pre> <a href="tqwidget.html#setCaption">setCaption</a>( TQString( "Chart -- %1" ).arg( filename ) );
|
|
|
|
|
updateRecentFiles( filename );
|
|
|
|
|
|
|
|
|
|
drawElements();
|
|
|
|
|
m_changed = FALSE;
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
<p> Loading a data set is very easy. We open the file and create a text
|
|
|
|
|
stream. While there's data to read we stream an element into <tt>element</tt> and if it is valid we insert it into the <tt>m_elements</tt> vector.
|
|
|
|
|
All the detail is handled by the <tt>Element</tt> class. Then we close
|
|
|
|
|
the file and update the caption and the recent files list. Finally we
|
|
|
|
|
draw the chart and mark it as unchanged.
|
|
|
|
|
<p> <h2> Writing Chart Data
|
|
|
|
|
</h2>
|
|
|
|
|
<a name="2"></a><p> <pre> void ChartForm::fileSave()
|
|
|
|
|
{
|
|
|
|
|
</pre><pre> <a href="ntqfile.html">TQFile</a> file( m_filename );
|
|
|
|
|
<a name="x2591"></a> if ( !file.<a href="ntqfile.html#open">open</a>( <a href="ntqfile.html#open">IO_WriteOnly</a> ) ) {
|
|
|
|
|
<a href="ntqmainwindow.html#statusBar">statusBar</a>()->message( TQString( "Failed to save \'%1\'" ).
|
|
|
|
|
arg( m_filename ), 2000 );
|
|
|
|
|
return;
|
|
|
|
|
}
|
|
|
|
|
<a href="tqtextstream.html">TQTextStream</a> ts( &file );
|
|
|
|
|
for ( int i = 0; i < MAX_ELEMENTS; ++i )
|
|
|
|
|
if ( m_elements[i].isValid() )
|
|
|
|
|
ts << m_elements[i];
|
|
|
|
|
|
|
|
|
|
file.<a href="ntqfile.html#close">close</a>();
|
|
|
|
|
|
|
|
|
|
<a href="tqwidget.html#setCaption">setCaption</a>( TQString( "Chart -- %1" ).arg( m_filename ) );
|
|
|
|
|
<a href="ntqmainwindow.html#statusBar">statusBar</a>()->message( TQString( "Saved \'%1\'" ).arg( m_filename ), 2000 );
|
|
|
|
|
m_changed = FALSE;
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
<p> Saving data is equally easy. We open the file and create a text
|
|
|
|
|
stream. We then stream every valid element to the text stream. All the
|
|
|
|
|
detail is handled by the <tt>Element</tt> class.
|
|
|
|
|
<p> <p align="right">
|
|
|
|
|
<a href="tutorial2-06.html">« Canvas Control</a> |
|
|
|
|
|
<a href="tutorial2.html">Contents</a> |
|
|
|
|
|
<a href="tutorial2-08.html">Taking Data »</a>
|
|
|
|
|
</p>
|
|
|
|
|
<p>
|
|
|
|
|
<!-- eof -->
|
|
|
|
|
<p><address><hr><div align=center>
|
|
|
|
|
<table width=100% cellspacing=0 border=0><tr>
|
|
|
|
|
<td>Copyright © 2007
|
|
|
|
|
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
|
|
|
|
|
<td align=right><div align=right>TQt 3.3.8</div>
|
|
|
|
|
</table></div></address></body>
|
|
|
|
|
</html>
|
