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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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7 ** This file is part of the documentation of the Qt Toolkit. |
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24 ** In addition, as a special exception, Nokia gives you certain additional |
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37 ** |
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38 ** $QT_END_LICENSE$ |
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39 ** |
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40 ****************************************************************************/ |
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41 |
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42 /*! |
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43 \example webkit/previewer |
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44 \title Previewer Example |
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45 |
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46 The Previewer example shows how to use QtWebKit's QWebView to preview |
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47 HTML data written in a QPlainTextEdit. |
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48 |
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49 \image previewer-example.png |
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50 |
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51 \section1 The User Interface |
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52 |
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53 Before we begin, we create a user interface using \QD. Two QGroupBox |
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54 objects - the editor group box and the previewer group box are separated |
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55 by a QSplitter. In the editor group box, we have a QPlainTextEdit object, |
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56 \c plainTextEdit, and two QPushButton objects. In the previewer group box, |
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57 we have a QWebView object, \c webView. |
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58 |
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59 \image previewer-ui.png |
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60 |
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61 \section1 Previewer Class Definition |
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62 |
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63 The \c Previewer class is a subclass of both QWidget and Ui::Form. |
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64 We subclass Ui::Form in order to embed the \QD user interface form |
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65 created earlier. This method of embedding forms is known as the |
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66 \l{The Multiple Inheritance Approach}{multiple inheritance approach}. |
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67 |
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68 In our \c previewer.h file, we have a constructor and a slot, |
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69 \c on_previewButton_clicked(). |
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70 |
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71 \snippet examples/webkit/previewer/previewer.h 0 |
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72 |
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73 \section1 Previewer Class Implementation |
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74 |
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75 The \c{Previewer}'s constructor is only responsible for setting up the |
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76 user interface. |
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77 |
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78 \snippet examples/webkit/previewer/previewer.cpp 0 |
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79 |
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80 The \c on_previewButton_clicked() is a slot corresponding to the |
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81 \c{previewButton}'s \l{QPushButton::}{clicked()} signal. When the |
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82 \c previewButton is clicked, we extract the contents of \c plainTextEdit, |
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83 and then invoke the \l{QWebView::}{setHtml()} function to display our |
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84 contents as HTML. |
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85 |
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86 \snippet examples/webkit/previewer/previewer.cpp 1 |
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87 |
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88 \section1 MainWindow Class Definition |
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89 |
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90 The \c MainWindow class for the Previewer example is a subclass of |
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91 QMainWindow with a constructor and five private slots: \c open(), |
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92 \c openUrl(), \c save(), \c about() and \c updateTextEdit(). |
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93 |
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94 \snippet examples/webkit/previewer/mainwindow.h 0 |
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95 |
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96 The private objects in \c MainWindow are \c centralWidget, which is |
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97 a \c Previewer object, \c fileMenu, \c helpMenu and the QAction objects |
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98 \c openAct, \c openUrlAct, \c saveAct, \c exitAct, \c aboutAct and |
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99 \c aboutQtAct. |
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100 |
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101 \snippet examples/webkit/previewer/mainwindow.h 1 |
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102 |
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103 There are three private functions: \c createActions(), \c createMenus() |
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104 and \c setStartupText(). The \c createActions() and \c createMenus() |
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105 functions are necessary to set up the main window's actions and |
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106 assign them to the \gui File and \gui Help menus. The \c setStartupText() |
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107 function, on the other hand, displays a description about the example |
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108 in its HTML Previewer window. |
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109 |
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110 \section1 MainWindow Class Implementation |
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111 |
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112 The \c{MainWindow}'s constructor invokes \c createActions() and |
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113 \c createMenus() to set up the \gui File menu and \gui Help menu. Then, |
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114 the \c Previewer object, \c centralWidget, is set to the main window's |
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115 central widget. Also, we connect \c webView's |
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116 \l{QWebView::}{loadFinished()} signal to our \c updateTextEdit() slot. |
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117 Finally, we call the \c setStartupText() function to display the |
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118 description of the example. |
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119 |
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120 \snippet examples/webkit/previewer/mainwindow.cpp 0 |
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121 |
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122 Within the \c createActions() function, we instantiate all our private |
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123 QAction objects which we declared in \c{mainwindow.h}. We set the |
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124 short cut and status tip for these actions and connect their |
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125 \l{QAction::}{triggered()} signal to appropriate slots. |
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126 |
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127 \snippet examples/webkit/previewer/mainwindow.cpp 1 |
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128 \dots |
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129 |
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130 The \c createMenus() function instantiates the QMenu items, \c fileMenu |
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131 and \c helpMenu and adds them to the main window's |
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132 \l{QMainWindow::menuBar()}{menu bar}. |
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133 |
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134 \snippet examples/webkit/previewer/mainwindow.cpp 2 |
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135 |
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136 The example also provides an \c about() slot to describe its purpose. |
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137 |
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138 \snippet examples/webkit/previewer/mainwindow.cpp 3 |
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139 |
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140 The \c MainWindow class provides two types of \gui Open functions: |
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141 \c open() and \c openUrl(). The \c open() function opens an HTML file |
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142 with \c fileName, and reads it with QTextStream. The function then |
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143 displays the output on \c plainTextEdit. The file's name is obtained |
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144 using QFileDialog's \l{QFileDialog::}{getOpenFileName()} function. |
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145 |
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146 \snippet examples/webkit/previewer/mainwindow.cpp 4 |
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147 |
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148 The \c openUrl() function, on the other hand, displays a QInputDialog |
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149 to obtain a URL, and displays it on \c webView. |
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150 |
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151 \snippet examples/webkit/previewer/mainwindow.cpp 5 |
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152 |
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153 In order to save a HTML file, the \c save() function first extracts the |
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154 contents of \c plainTextEdit and displays a QFileDialog to obtain |
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155 \c fileName. Then, we use a QTextStream object, \c in, to write to |
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156 \c file. |
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157 |
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158 \snippet examples/webkit/previewer/mainwindow.cpp 6 |
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159 |
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160 Earlier, in \c{MainWindow}'s constructor, we connected \c{webView}'s |
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161 \l{QWebView::}{loadFinished()} signal to our private \c updateTextEdit() |
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162 slot. This slot updates the contents of \c plainTextEdit with the HTML |
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163 source of the web page's main frame, obtained using \l{QWebFrame}'s |
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164 \l{QWebFrame::}{toHtml()} function. |
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165 |
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166 \snippet examples/webkit/previewer/mainwindow.cpp 7 |
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167 |
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168 To provide a description about the Previewer example, when it starts up, |
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169 we use the \c setStartupText() function, as shown below: |
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170 |
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171 \snippet examples/webkit/previewer/mainwindow.cpp 8 |
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172 |
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173 |
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174 \section1 The \c{main()} Function |
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175 |
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176 The \c main() function instantiates a \c MainWindow object, \c mainWindow, |
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177 and displays it with the \l{QWidget::}{show()} function. |
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178 |
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179 \snippet examples/webkit/previewer/main.cpp 0 |
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180 |
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181 */ |