|
1 /**************************************************************************** |
|
2 ** |
|
3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
|
4 ** All rights reserved. |
|
5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
|
6 ** |
|
7 ** This file is part of the documentation of the Qt Toolkit. |
|
8 ** |
|
9 ** $QT_BEGIN_LICENSE:LGPL$ |
|
10 ** No Commercial Usage |
|
11 ** This file contains pre-release code and may not be distributed. |
|
12 ** You may use this file in accordance with the terms and conditions |
|
13 ** contained in the Technology Preview License Agreement accompanying |
|
14 ** this package. |
|
15 ** |
|
16 ** GNU Lesser General Public License Usage |
|
17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
|
18 ** General Public License version 2.1 as published by the Free Software |
|
19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
|
20 ** packaging of this file. Please review the following information to |
|
21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
|
22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
|
23 ** |
|
24 ** In addition, as a special exception, Nokia gives you certain additional |
|
25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
|
26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
|
27 ** |
|
28 ** If you have questions regarding the use of this file, please contact |
|
29 ** Nokia at qt-info@nokia.com. |
|
30 ** |
|
31 ** |
|
32 ** |
|
33 ** |
|
34 ** |
|
35 ** |
|
36 ** |
|
37 ** |
|
38 ** $QT_END_LICENSE$ |
|
39 ** |
|
40 ****************************************************************************/ |
|
41 |
|
42 /*! |
|
43 \example widgets/digitalclock |
|
44 \title Digital Clock Example |
|
45 |
|
46 The Digital Clock example shows how to use QLCDNumber to display a |
|
47 number with LCD-like digits. |
|
48 |
|
49 \image digitalclock-example.png Screenshot of the Digital Clock example |
|
50 |
|
51 This example also demonstrates how QTimer can be used to update a widget |
|
52 at regular intervals. |
|
53 |
|
54 \section1 DigitalClock Class Definition |
|
55 |
|
56 The \c DigitalClock class provides a clock widget showing the time with |
|
57 hours and minutes separated by a blinking colon. We subclass QLCDNumber |
|
58 and implement a private slot called \c showTime() to update the clock |
|
59 display: |
|
60 |
|
61 \snippet examples/widgets/digitalclock/digitalclock.h 0 |
|
62 |
|
63 \section1 DigitalClock Class Implementation |
|
64 |
|
65 \snippet examples/widgets/digitalclock/digitalclock.cpp 0 |
|
66 |
|
67 In the constructor, we first change the look of the LCD numbers. The |
|
68 QLCDNumber::Filled style produces raised segments filled with the |
|
69 foreground color (typically black). We also set up a one-second timer |
|
70 to keep track of the current time, and we connect |
|
71 its \l{QTimer::timeout()}{timeout()} signal to the private \c showTime() slot |
|
72 so that the display is updated every second. Then, we |
|
73 call the \c showTime() slot; without this call, there would be a one-second |
|
74 delay at startup before the time is shown. |
|
75 |
|
76 \snippet examples/widgets/digitalclock/digitalclock.cpp 1 |
|
77 \snippet examples/widgets/digitalclock/digitalclock.cpp 2 |
|
78 |
|
79 The \c showTime() slot is called whenever the clock display needs |
|
80 to be updated. |
|
81 |
|
82 The current time is converted into a string with the format "hh:mm". |
|
83 When QTime::second() is a even number, the colon in the string is |
|
84 replaced with a space. This makes the colon appear and vanish every |
|
85 other second. |
|
86 |
|
87 Finally, we call QLCDNumber::display() to update the widget. |
|
88 */ |