1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
<!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/tutorial.doc:580 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>TQt Tutorial - Chapter 6: Building Blocks Galore!</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>TQt Tutorial - Chapter 6: Building Blocks Galore!</h1>
<p> <center><img src="t6.png" alt="Screenshot of tutorial six"></center>
<p> This example shows how to encapsulate two widgets into a new component and
how easy it is to use many widgets. For the first time, we use a custom
widget as a child widget.
<p> <a name="main"></a>
<pre>/****************************************************************
**
** TQt tutorial 6
**
****************************************************************/
#include <<a href="qapplication-h.html">qapplication.h</a>>
#include <<a href="qpushbutton-h.html">qpushbutton.h</a>>
#include <<a href="qslider-h.html">qslider.h</a>>
#include <<a href="qlcdnumber-h.html">qlcdnumber.h</a>>
#include <<a href="qfont-h.html">qfont.h</a>>
#include <<a href="qvbox-h.html">qvbox.h</a>>
#include <<a href="qgrid-h.html">qgrid.h</a>>
class LCDRange : public <a href="qvbox.html">TQVBox</a>
{
public:
LCDRange( <a href="qwidget.html">TQWidget</a> *parent=0, const char *name=0 );
};
<a name="f554"></a>LCDRange::LCDRange( <a href="qwidget.html">TQWidget</a> *parent, const char *name )
: <a href="qvbox.html">TQVBox</a>( parent, name )
{
<a href="qlcdnumber.html">TQLCDNumber</a> *lcd = new <a href="qlcdnumber.html">TQLCDNumber</a>( 2, this, "lcd" );
<a href="qslider.html">TQSlider</a> * slider = new <a href="qslider.html">TQSlider</a>( Horizontal, this, "slider" );
slider-><a href="qrangecontrol.html#setRange">setRange</a>( 0, 99 );
slider-><a href="qslider.html#setValue">setValue</a>( 0 );
<a href="qobject.html#connect">connect</a>( slider, SIGNAL(<a href="qslider.html#valueChanged">valueChanged</a>(int)), lcd, SLOT(<a href="qlcdnumber.html#display">display</a>(int)) );
}
class MyWidget : public <a href="qvbox.html">TQVBox</a>
{
public:
MyWidget( <a href="qwidget.html">TQWidget</a> *parent=0, const char *name=0 );
};
<a name="f555"></a>MyWidget::MyWidget( <a href="qwidget.html">TQWidget</a> *parent, const char *name )
: <a href="qvbox.html">TQVBox</a>( parent, name )
{
<a href="qpushbutton.html">TQPushButton</a> *tquit = new <a href="qpushbutton.html">TQPushButton</a>( "Quit", this, "tquit" );
tquit-><a href="qwidget.html#setFont">setFont</a>( TQFont( "Times", 18, TQFont::Bold ) );
<a href="qobject.html#connect">connect</a>( tquit, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), qApp, SLOT(<a href="qapplication.html#tquit">tquit</a>()) );
<a href="qgrid.html">TQGrid</a> *grid = new <a href="qgrid.html">TQGrid</a>( 4, this );
for( int r = 0 ; r < 4 ; r++ )
for( int c = 0 ; c < 4 ; c++ )
(void)new LCDRange( grid );
}
int main( int argc, char **argv )
{
<a href="qapplication.html">TQApplication</a> a( argc, argv );
MyWidget w;
a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &w );
w.<a href="qwidget.html#show">show</a>();
return a.<a href="qapplication.html#exec">exec</a>();
}
</pre>
<p> <h2> Line-by-line Walkthrough
</h2>
<a name="1"></a><p> <pre> class LCDRange : public <a href="qvbox.html">TQVBox</a>
{
public:
LCDRange( <a href="qwidget.html">TQWidget</a> *parent=0, const char *name=0 );
};
</pre>
<p> The LCDRange widget is a widget without any API. It just has a
constructor. This sort of widget is not very useful, so we'll add some API later.
<p> <pre> LCDRange::LCDRange( <a href="qwidget.html">TQWidget</a> *parent, const char *name )
: <a href="qvbox.html">TQVBox</a>( parent, name )
{
<a href="qlcdnumber.html">TQLCDNumber</a> *lcd = new <a href="qlcdnumber.html">TQLCDNumber</a>( 2, this, "lcd" );
<a href="qslider.html">TQSlider</a> * slider = new <a href="qslider.html">TQSlider</a>( Horizontal, this, "slider" );
<a name="x2325"></a> slider-><a href="qrangecontrol.html#setRange">setRange</a>( 0, 99 );
<a name="x2326"></a> slider-><a href="qslider.html#setValue">setValue</a>( 0 );
<a name="x2327"></a><a name="x2324"></a> <a href="qobject.html#connect">connect</a>( slider, SIGNAL(<a href="qslider.html#valueChanged">valueChanged</a>(int)), lcd, SLOT(<a href="qlcdnumber.html#display">display</a>(int)) );
}
</pre>
<p> This is lifted straight from the
<a href="tutorial1-05.html#constructor">MyWidget constructor</a> in Chapter 5.
The only differences are that the button is left out and the class
is renamed.
<p> <pre> class MyWidget : public <a href="qvbox.html">TQVBox</a>
{
public:
MyWidget( <a href="qwidget.html">TQWidget</a> *parent=0, const char *name=0 );
};
</pre>
<p> MyWidget, too, contains no API except a constructor.
<p> <pre> MyWidget::MyWidget( <a href="qwidget.html">TQWidget</a> *parent, const char *name )
: <a href="qvbox.html">TQVBox</a>( parent, name )
{
<a href="qpushbutton.html">TQPushButton</a> *tquit = new <a href="qpushbutton.html">TQPushButton</a>( "Quit", this, "tquit" );
<a name="x2328"></a> tquit-><a href="qwidget.html#setFont">setFont</a>( TQFont( "Times", 18, TQFont::Bold ) );
<a name="x2321"></a> <a href="qobject.html#connect">connect</a>( tquit, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), qApp, SLOT(<a href="qapplication.html#tquit">tquit</a>()) );
</pre>
<p> The push button that used to be in what is now LCDRange has been
separated so that we can have one "Quit" button and many LCDRange
objects.
<p> <pre> <a href="qgrid.html">TQGrid</a> *grid = new <a href="qgrid.html">TQGrid</a>( 4, this );
</pre>
<p> We create a <a href="qgrid.html">TQGrid</a> object with four columns. The TQGRid widget
automatically arranges its children in rows and columns; you can
specify the number of rows or of columns, and TQGrid will discover its
new children and fit them into the grid.
<p> <pre> for( int r = 0 ; r < 4 ; r++ )
for( int c = 0 ; c < 4 ; c++ )
(void)new LCDRange( grid );
</pre>
<p> Four columns, four rows.
<p> We create 4*4 LCDRanges, all of which are children of the grid object.
The TQGrid widget will arrange them.
<p> <pre> }
</pre>
<p> That's all.
<p> <h2> Behavior
</h2>
<a name="2"></a><p> This program shows how easy it is to use many widgets at a time. Each
one behaves like the slider and LCD number in the previous
chapter. Again, the difference lies in the implementation.
<p> (See <a href="tutorial1-01.html#compiling">Compiling</a> for how to create a
makefile and build the application.)
<p> <h2> Exercises
</h2>
<a name="3"></a><p> Initialize each slider with a different/random value on startup.
<p> The source contains three occurrences of "4". What happens if you
change the one in the <a href="qgrid.html">TQGrid</a> constructor call? What about the other
two? Why is this?
<p> You're now ready for <a href="tutorial1-07.html">Chapter 7.</a>
<p> [<a href="tutorial1-05.html">Previous tutorial</a>]
[<a href="tutorial1-07.html">Next tutorial</a>]
[<a href="tutorial.html">Main tutorial page</a>]
<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>
|
