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6<title>How to create a large, sparse QTable</title>
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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>How to create a large, sparse QTable</h1>
33
34
35<p>
36<p> This example shows a sparse table implementation using a <a href="qintdict.html">QIntDict</a> to
37keep track of the cells that are actually in use.
38<p> <hr>
39<p> Implementation:
40<p> <pre>/****************************************************************************
41** $Id: bigtable-example.html 2051 2007-02-21 10:04:20Z chehrlic $
42**
43** Copyright (C) 1992-2007 Trolltech ASA. All rights reserved.
44**
45** This file is part of an example program for Qt. This example
46** program may be used, distributed and modified without limitation.
47**
48*****************************************************************************/
49
50#include &lt;<a href="qapplication-h.html">qapplication.h</a>&gt;
51#include &lt;<a href="qtable-h.html">qtable.h</a>&gt;
52
53// Table size
54
55const int numRows = 1000000;
56const int numCols = 1000000;
57
58class MyTable : public <a href="qtable.html">QTable</a>
59{
60public:
61 MyTable( int r, int c ) : <a href="qtable.html">QTable</a>( r, c ) {
62<a name="x1291"></a> items.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE );
63 widgets.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE );
64 setCaption( tr( "A 1 Million x 1 Million Cell Table" ) );
65 setLeftMargin( fontMetrics().width( "W999999W" ) );
66 }
67
68 void resizeData( int ) {}
69<a name="x1286"></a> <a href="qtableitem.html">QTableItem</a> *item( int r, int c ) const { return items.<a href="qintdict.html#find">find</a>( indexOf( r, c ) ); }
70<a name="x1288"></a> void setItem( int r, int c, QTableItem *i ) { items.<a href="qintdict.html#replace">replace</a>( indexOf( r, c ), i ); }
71<a name="x1287"></a> void clearCell( int r, int c ) { items.<a href="qintdict.html#remove">remove</a>( indexOf( r, c ) ); }
72 void takeItem( <a href="qtableitem.html">QTableItem</a> *item )
73 {
74 items.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( FALSE );
75<a name="x1294"></a><a name="x1293"></a> items.<a href="qintdict.html#remove">remove</a>( indexOf( item-&gt;<a href="qtableitem.html#row">row</a>(), item-&gt;<a href="qtableitem.html#col">col</a>() ) );
76 items.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE );
77 }
78 void insertWidget( int r, int c, QWidget *w ) { widgets.<a href="qintdict.html#replace">replace</a>( indexOf( r, c ), w ); }
79 <a href="qwidget.html">QWidget</a> *cellWidget( int r, int c ) const { return widgets.<a href="qintdict.html#find">find</a>( indexOf( r, c ) ); }
80 void clearCellWidget( int r, int c )
81 {
82<a name="x1289"></a> <a href="qwidget.html">QWidget</a> *w = widgets.<a href="qintdict.html#take">take</a>( indexOf( r, c ) );
83 if ( w )
84<a name="x1290"></a> w-&gt;<a href="qobject.html#deleteLater">deleteLater</a>();
85 }
86
87private:
88 <a href="qintdict.html">QIntDict</a>&lt;QTableItem&gt; items;
89 <a href="qintdict.html">QIntDict</a>&lt;QWidget&gt; widgets;
90
91};
92
93// The program starts here.
94
95int main( int argc, char **argv )
96{
97 <a href="qapplication.html">QApplication</a> app( argc, argv );
98
99 MyTable table( numRows, numCols );
100 app.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &amp;table );
101<a name="x1292"></a> table.<a href="qwidget.html#show">show</a>();
102 return app.<a href="qapplication.html#exec">exec</a>();
103}
104</pre>
105
106<p> <p>See also <a href="table-examples.html">Table Examples</a>.
107
108<!-- eof -->
109<p><address><hr><div align=center>
110<table width=100% cellspacing=0 border=0><tr>
111<td>Copyright &copy; 2007
112<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
113<td align=right><div align=right>Qt 3.3.8</div>
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