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40 ****************************************************************************/ |
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41 |
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42 /*! |
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43 \example designer/calculatorbuilder |
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44 \title Calculator Builder Example |
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45 |
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46 The Calculator Builder example shows how to create a user interface from |
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47 a \QD form at run-time, using the QUiLoader class. |
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48 |
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49 \image calculatorbuilder-example.png |
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50 |
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51 We use the form created in the \l{designer/calculatorform}{Calculator Form} |
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52 example to show that the same user interface can be generated when the |
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53 application is executed or defined when the application is built. |
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54 |
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55 \section1 Preparation |
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56 |
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57 The \l{designer/calculatorform}{Calculator Form} example defines a user |
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58 interface that we can use without modification. In this example, we use a |
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59 \l{The Qt Resource System}{resource file} to contain the \c{calculatorform.ui} |
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60 file created in the previous example, but it could be stored on disk instead. |
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61 |
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62 To generate a form at run time, we need to link the example against the |
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63 \c QtUiTools module library. The project file we use contains all the |
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64 necessary information to do this: |
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65 |
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66 \snippet examples/designer/calculatorbuilder/calculatorbuilder.pro 0 |
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67 |
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68 All the other necessary files are declared as usual. |
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69 |
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70 \section1 CalculatorForm Class Definition |
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71 |
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72 The \c CalculatorForm class defines the widget used to host the form's |
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73 user interface: |
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74 |
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75 \snippet examples/designer/calculatorbuilder/calculatorform.h 0 |
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76 |
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77 Note that we do not need to include a header file to describe the user |
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78 interface. We only define two public slots, using the auto-connection |
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79 naming convention required by \c uic, and declare private variables |
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80 that we will use to access widgets provided by the form after they are |
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81 constructed. |
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82 |
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83 \section1 CalculatorForm Class Implementation |
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84 |
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85 We will need to use the QUiLoader class that is provided by the |
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86 \c libQtUiTools library, so we first ensure that we include the header |
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87 file for the module: |
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88 |
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89 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 0 |
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90 |
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91 The constructor uses a form loader object to construct the user |
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92 interface that we retrieve, via a QFile object, from the example's |
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93 resources: |
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94 |
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95 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 1 |
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96 |
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97 By including the user interface in the example's resources, we ensure |
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98 that it will be present when the example is run. The \c{loader.load()} |
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99 function takes the user interface description contained in the file |
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100 and constructs the form widget as a child widget of the \c{CalculatorForm}. |
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101 |
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102 We are interested in three widgets in the generated user interface: |
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103 two spin boxes and a label. For convenience, we retrieve pointers to |
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104 these widgets from the widget that was constructed by the \c FormBuilder, |
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105 and we record them for later use. The \c qFindChild() template function |
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106 allows us to query widgets in order to find named child widgets. |
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107 |
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108 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 2 |
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109 |
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110 The widgets created by the form loader need to be connected to the |
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111 specially-named slots in the \c CalculatorForm object. We use Qt's |
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112 meta-object system to enable these connections: |
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113 |
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114 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 3 |
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115 |
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116 The form widget is added to a layout, and the window title is set: |
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117 |
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118 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 4 |
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119 |
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120 The two slots that modify widgets provided by the form are defined |
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121 in a similar way to those in the \l{designer/calculatorform}{Calculator |
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122 Form} example, except that we read the values from the spin boxes and |
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123 write the result to the output widget via the pointers we recorded in |
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124 the constructor: |
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125 |
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126 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 5 |
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127 \codeline |
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128 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 7 |
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129 |
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130 The advantage of this approach is that we can replace the form when the |
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131 application is run, but we can still manipulate the widgets it contains |
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132 as long as they are given appropriate names. |
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133 */ |