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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
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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 dialogs/extension |
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44 \title Extension Example |
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45 |
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46 The Extension example shows how to add an extension to a QDialog |
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47 using the QAbstractButton::toggled() signal and the |
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48 QWidget::setVisible() slot. |
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49 |
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50 \image extension-example.png Screenshot of the Extension example |
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51 |
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52 The Extension application is a dialog that allows the user to |
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53 perform a simple search as well as a more advanced search. |
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54 |
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55 The simple search has two options: \gui {Match case} and \gui |
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56 {Search from start}. The advanced search options include the |
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57 possibilities to search for \gui {Whole words}, \gui {Search |
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58 backward} and \gui {Search selection}. Only the simple search is |
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59 visible when the application starts. The advanced search options |
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60 are located in the application's extension part, and can be made |
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61 visible by pressing the \gui More button: |
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62 |
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63 \image extension_more.png Screenshot of the Extension example |
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64 |
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65 \section1 FindDialog Class Definition |
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66 |
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67 The \c FindDialog class inherits QDialog. The QDialog class is the |
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68 base class of dialog windows. A dialog window is a top-level |
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69 window mostly used for short-term tasks and brief communications |
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70 with the user. |
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71 |
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72 \snippet examples/dialogs/extension/finddialog.h 0 |
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73 |
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74 The \c FindDialog widget is the main application widget, and |
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75 displays the application's search options and controlling |
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76 buttons. |
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77 |
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78 In addition to a constructor, we declare the several child |
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79 widgets: We need a QLineEdit with an associated QLabel to let the |
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80 user type a word to search for, we need several \l |
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81 {QCheckBox}{QCheckBox}es to facilitate the search options, and we |
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82 need three \l {QPushButton}{QPushButton}s: the \gui Find button to |
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83 start a search and the \gui More button to enable an advanced search. |
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84 Finally, we need a QWidget representing the application's extension |
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85 part. |
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86 |
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87 \section1 FindDialog Class Implementation |
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88 |
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89 In the constructor we first create the standard child widgets for |
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90 the simple search: the QLineEdit with the associated QLabel, two |
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91 of the \l {QCheckBox}{QCheckBox}es and all the \l |
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92 {QPushButton}{QPushButton}s. |
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93 |
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94 \snippet examples/dialogs/extension/finddialog.cpp 0 |
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95 |
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96 We give the options and buttons a shortcut key using the & |
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97 character. In the \gui {Find what} option's case, we also need to |
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98 use the QLabel::setBuddy() function to make the shortcut key work |
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99 as expected; then, when the user presses the shortcut key |
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100 indicated by the label, the keyboard focus is transferred to the |
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101 label's buddy widget, the QLineEdit. |
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102 |
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103 We set the \gui Find button's default property to true, using the |
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104 QPushButton::setDefault() function. Then the push button will be |
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105 pressed if the user presses the Enter (or Return) key. Note that a |
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106 QDialog can only have one default button. |
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107 |
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108 \snippet examples/dialogs/extension/finddialog.cpp 2 |
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109 |
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110 Then we create the extension widget, and the \l |
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111 {QCheckBox}{QCheckBox}es associated with the advanced search |
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112 options. |
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113 |
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114 \snippet examples/dialogs/extension/finddialog.cpp 3 |
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115 |
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116 Now that the extension widget is created, we can connect the \gui |
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117 More button's \l{QAbstractButton::toggled()}{toggled()} signal to |
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118 the extension widget's \l{QWidget::setVisible()}{setVisible()} slot. |
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119 |
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120 The QAbstractButton::toggled() signal is emitted whenever a |
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121 checkable button changes its state. The signal's argument is true |
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122 if the button is checked, or false if the button is unchecked. The |
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123 QWidget::setVisible() slot sets the widget's visible status. If |
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124 the status is true the widget is shown, otherwise the widget is |
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125 hidden. |
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126 |
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127 Since we made the \gui More button checkable when we created it, |
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128 the connection makes sure that the extension widget is shown |
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129 depending on the state of \gui More button. |
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130 |
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131 We also put the check boxes associated with the advanced |
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132 search options into a layout we install on the extension widget. |
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133 |
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134 \snippet examples/dialogs/extension/finddialog.cpp 4 |
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135 |
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136 Before we create the main layout, we create several child layouts |
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137 for the widgets: First we allign the QLabel ans its buddy, the |
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138 QLineEdit, using a QHBoxLayout. Then we vertically allign the |
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139 QLabel and QLineEdit with the check boxes associated with the |
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140 simple search, using a QVBoxLayout. We also create a QVBoxLayout |
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141 for the buttons. In the end we lay out the two latter layouts and |
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142 the extension widget using a QGridLayout. |
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143 |
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144 \snippet examples/dialogs/extension/finddialog.cpp 5 |
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145 |
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146 Finally, we hide the extension widget using the QWidget::hide() |
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147 function, making the application only show the simple search |
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148 options when it starts. When the user wants to access the advanced |
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149 search options, the dialog only needs to change the visibility of |
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150 the extension widget. Qt's layout management takes care of the |
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151 dialog's appearance. |
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152 */ |