|
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 webkit/previewer |
|
44 \title Previewer Example |
|
45 |
|
46 The Previewer example shows how to use QtWebKit's QWebView to preview |
|
47 HTML data written in a QPlainTextEdit. |
|
48 |
|
49 \image previewer-example.png |
|
50 |
|
51 \section1 The User Interface |
|
52 |
|
53 Before we begin, we create a user interface using \QD. Two QGroupBox |
|
54 objects - the editor group box and the previewer group box are separated |
|
55 by a QSplitter. In the editor group box, we have a QPlainTextEdit object, |
|
56 \c plainTextEdit, and two QPushButton objects. In the previewer group box, |
|
57 we have a QWebView object, \c webView. |
|
58 |
|
59 \image previewer-ui.png |
|
60 |
|
61 \section1 Previewer Class Definition |
|
62 |
|
63 The \c Previewer class is a subclass of both QWidget and Ui::Form. |
|
64 We subclass Ui::Form in order to embed the \QD user interface form |
|
65 created earlier. This method of embedding forms is known as the |
|
66 \l{The Multiple Inheritance Approach}{multiple inheritance approach}. |
|
67 |
|
68 In our \c previewer.h file, we have a constructor and a slot, |
|
69 \c on_previewButton_clicked(). |
|
70 |
|
71 \snippet examples/webkit/previewer/previewer.h 0 |
|
72 |
|
73 \section1 Previewer Class Implementation |
|
74 |
|
75 The \c{Previewer}'s constructor is only responsible for setting up the |
|
76 user interface. |
|
77 |
|
78 \snippet examples/webkit/previewer/previewer.cpp 0 |
|
79 |
|
80 The \c on_previewButton_clicked() is a slot corresponding to the |
|
81 \c{previewButton}'s \l{QPushButton::}{clicked()} signal. When the |
|
82 \c previewButton is clicked, we extract the contents of \c plainTextEdit, |
|
83 and then invoke the \l{QWebView::}{setHtml()} function to display our |
|
84 contents as HTML. |
|
85 |
|
86 \snippet examples/webkit/previewer/previewer.cpp 1 |
|
87 |
|
88 \section1 MainWindow Class Definition |
|
89 |
|
90 The \c MainWindow class for the Previewer example is a subclass of |
|
91 QMainWindow with a constructor and five private slots: \c open(), |
|
92 \c openUrl(), \c save(), \c about() and \c updateTextEdit(). |
|
93 |
|
94 \snippet examples/webkit/previewer/mainwindow.h 0 |
|
95 |
|
96 The private objects in \c MainWindow are \c centralWidget, which is |
|
97 a \c Previewer object, \c fileMenu, \c helpMenu and the QAction objects |
|
98 \c openAct, \c openUrlAct, \c saveAct, \c exitAct, \c aboutAct and |
|
99 \c aboutQtAct. |
|
100 |
|
101 \snippet examples/webkit/previewer/mainwindow.h 1 |
|
102 |
|
103 There are three private functions: \c createActions(), \c createMenus() |
|
104 and \c setStartupText(). The \c createActions() and \c createMenus() |
|
105 functions are necessary to set up the main window's actions and |
|
106 assign them to the \gui File and \gui Help menus. The \c setStartupText() |
|
107 function, on the other hand, displays a description about the example |
|
108 in its HTML Previewer window. |
|
109 |
|
110 \section1 MainWindow Class Implementation |
|
111 |
|
112 The \c{MainWindow}'s constructor invokes \c createActions() and |
|
113 \c createMenus() to set up the \gui File menu and \gui Help menu. Then, |
|
114 the \c Previewer object, \c centralWidget, is set to the main window's |
|
115 central widget. Also, we connect \c webView's |
|
116 \l{QWebView::}{loadFinished()} signal to our \c updateTextEdit() slot. |
|
117 Finally, we call the \c setStartupText() function to display the |
|
118 description of the example. |
|
119 |
|
120 \snippet examples/webkit/previewer/mainwindow.cpp 0 |
|
121 |
|
122 Within the \c createActions() function, we instantiate all our private |
|
123 QAction objects which we declared in \c{mainwindow.h}. We set the |
|
124 short cut and status tip for these actions and connect their |
|
125 \l{QAction::}{triggered()} signal to appropriate slots. |
|
126 |
|
127 \snippet examples/webkit/previewer/mainwindow.cpp 1 |
|
128 \dots |
|
129 |
|
130 The \c createMenus() function instantiates the QMenu items, \c fileMenu |
|
131 and \c helpMenu and adds them to the main window's |
|
132 \l{QMainWindow::menuBar()}{menu bar}. |
|
133 |
|
134 \snippet examples/webkit/previewer/mainwindow.cpp 2 |
|
135 |
|
136 The example also provides an \c about() slot to describe its purpose. |
|
137 |
|
138 \snippet examples/webkit/previewer/mainwindow.cpp 3 |
|
139 |
|
140 The \c MainWindow class provides two types of \gui Open functions: |
|
141 \c open() and \c openUrl(). The \c open() function opens an HTML file |
|
142 with \c fileName, and reads it with QTextStream. The function then |
|
143 displays the output on \c plainTextEdit. The file's name is obtained |
|
144 using QFileDialog's \l{QFileDialog::}{getOpenFileName()} function. |
|
145 |
|
146 \snippet examples/webkit/previewer/mainwindow.cpp 4 |
|
147 |
|
148 The \c openUrl() function, on the other hand, displays a QInputDialog |
|
149 to obtain a URL, and displays it on \c webView. |
|
150 |
|
151 \snippet examples/webkit/previewer/mainwindow.cpp 5 |
|
152 |
|
153 In order to save a HTML file, the \c save() function first extracts the |
|
154 contents of \c plainTextEdit and displays a QFileDialog to obtain |
|
155 \c fileName. Then, we use a QTextStream object, \c in, to write to |
|
156 \c file. |
|
157 |
|
158 \snippet examples/webkit/previewer/mainwindow.cpp 6 |
|
159 |
|
160 Earlier, in \c{MainWindow}'s constructor, we connected \c{webView}'s |
|
161 \l{QWebView::}{loadFinished()} signal to our private \c updateTextEdit() |
|
162 slot. This slot updates the contents of \c plainTextEdit with the HTML |
|
163 source of the web page's main frame, obtained using \l{QWebFrame}'s |
|
164 \l{QWebFrame::}{toHtml()} function. |
|
165 |
|
166 \snippet examples/webkit/previewer/mainwindow.cpp 7 |
|
167 |
|
168 To provide a description about the Previewer example, when it starts up, |
|
169 we use the \c setStartupText() function, as shown below: |
|
170 |
|
171 \snippet examples/webkit/previewer/mainwindow.cpp 8 |
|
172 |
|
173 |
|
174 \section1 The \c{main()} Function |
|
175 |
|
176 The \c main() function instantiates a \c MainWindow object, \c mainWindow, |
|
177 and displays it with the \l{QWidget::}{show()} function. |
|
178 |
|
179 \snippet examples/webkit/previewer/main.cpp 0 |
|
180 |
|
181 */ |