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40 ****************************************************************************/ |
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41 |
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42 /*! |
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43 \example itemviews/simplewidgetmapper |
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44 \title Simple Widget Mapper Example |
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45 |
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46 The Simple Widget Mapper example shows how to use a widget mapper to display |
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47 data from a model in a collection of widgets. |
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48 |
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49 \image simplewidgetmapper-example.png |
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50 |
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51 The QDataWidgetMapper class allows information obtained from a |
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52 \l{Model Classes}{model} to be viewed and edited in a collection of |
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53 widgets instead of in an \l{View Classes}{item view}. |
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54 Any model derived from QAbstractItemModel can be used as the source of |
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55 data and almost any input widget can be used to display it. |
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56 |
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57 The example itself is very simple: we create \c Window, a QWidget subclass |
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58 that we use to hold the widgets used to present the data, and show it. The |
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59 \c Window class will provide buttons that the user can click to show |
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60 different records from the model. |
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61 |
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62 \section1 Window Class Definition |
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63 |
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64 The class provides a constructor, a slot to keep the buttons up to date, |
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65 and a private function to set up the model: |
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66 |
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67 \snippet examples/itemviews/simplewidgetmapper/window.h Window definition |
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68 |
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69 In addition to the QDataWidgetMapper object and the controls used to make |
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70 up the user interface, we use a QStandardItemModel to hold our data. |
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71 We could use a custom model, but this standard implementation is sufficient |
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72 for our purposes. |
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73 |
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74 \section1 Window Class Implementation |
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75 |
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76 The constructor of the \c Window class can be explained in three parts. |
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77 In the first part, we set up the widgets used for the user interface: |
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78 |
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79 \snippet examples/itemviews/simplewidgetmapper/window.cpp Set up widgets |
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80 |
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81 We also set up the buddy relationships between various labels and the |
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82 corresponding input widgets. |
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83 |
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84 Next, we set up the widget mapper, relating each input widget to a column |
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85 in the model specified by the call to \l{QDataWidgetMapper::}{setModel()}: |
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86 |
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87 \snippet examples/itemviews/simplewidgetmapper/window.cpp Set up the mapper |
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88 |
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89 We also connect the mapper to the \gui{Next} and \gui{Previous} buttons |
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90 via its \l{QDataWidgetMapper::}{toNext()} and |
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91 \l{QDataWidgetMapper::}{toPrevious()} slots. The mapper's |
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92 \l{QDataWidgetMapper::}{currentIndexChanged()} signal is connected to the |
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93 \c{updateButtons()} slot in the window which we'll show later. |
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94 |
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95 In the final part of the constructor, we set up the layout, placing each |
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96 of the widgets in a grid (we could also use a QFormLayout for this): |
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97 |
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98 \snippet examples/itemviews/simplewidgetmapper/window.cpp Set up the layout |
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99 |
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100 Lastly, we set the window title and initialize the mapper by setting it to |
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101 refer to the first row in the model. |
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102 |
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103 The model is initialized in the window's \c{setupModel()} function. Here, |
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104 we create a standard model with 5 rows and 3 columns, and we insert some |
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105 sample names, addresses and ages into each row: |
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106 |
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107 \snippet examples/itemviews/simplewidgetmapper/window.cpp Set up the model |
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108 |
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109 As a result, each row can be treated like a record in a database, and the |
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110 widget mapper will read the data from each row, using the column numbers |
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111 specified earlier to access the correct data for each widget. This is |
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112 shown in the following diagram: |
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113 |
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114 \image widgetmapper-simple-mapping.png |
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115 |
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116 Since the user can navigate using the buttons in the user interface, the |
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117 example is fully-functional at this point, but to make it a bit more |
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118 user-friendly, we implement the \c{updateButtons()} slot to show when the |
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119 user is viewing the first or last records: |
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120 |
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121 \snippet examples/itemviews/simplewidgetmapper/window.cpp Slot for updating the buttons |
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122 |
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123 If the mapper is referring to the first row in the model, the \gui{Previous} |
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124 button is disabled. Similarly, the \gui{Next} button is disabled if the |
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125 mapper reaches the last row in the model. |
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126 |
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127 \section1 More Complex Mappings |
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128 |
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129 The QDataWidgetMapper class makes it easy to relate information from a |
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130 model to widgets in a user interface. However, it is sometimes necessary |
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131 to use input widgets which offer choices to the user, such as QComboBox, |
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132 in conjunction with a widget mapper. |
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133 |
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134 In these situations, although the mapping to input widgets remains simple, |
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135 more work needs to be done to expose additional data to the widget mapper. |
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136 This is covered by the \l{Combo Widget Mapper Example}{Combo Widget Mapper} |
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137 and \l{SQL Widget Mapper Example}{SQL Widget Mapper} |
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138 examples. |
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139 */ |