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40 ****************************************************************************/ |
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41 |
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42 /*! |
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43 \example designer/calculatorform |
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44 \title Calculator Form Example |
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45 |
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46 The Calculator Form Example shows how to use a form created with |
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47 \QD in an application by using the user interface information from |
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48 a QWidget subclass. We use \l{Using a Designer UI File in Your Application} |
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49 {uic's auto-connection} feature to automatically connect signals |
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50 from widgets on the form to slots in our code. |
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51 |
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52 \image calculatorform-example.png Screenshot of the Calculator Form example |
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53 |
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54 The example presents two spin boxes that are used to input integer values |
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55 and a label that shows their sum. Whenever either of the spin boxes are |
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56 updated, the signal-slot connections between the widgets and the form |
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57 ensure that the label is also updated. |
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58 |
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59 \section1 Preparation |
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60 |
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61 The user interface for this example is designed completely using \QD. The |
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62 result is a UI file describing the form, the widgets used, any signal-slot |
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63 connections between them, and other standard user interface properties. |
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64 |
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65 To ensure that the example can use this file, we need to include a \c FORMS |
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66 declaration in the example's project file: |
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67 |
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68 \snippet examples/designer/calculatorform/calculatorform.pro 1 |
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69 |
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70 When the project is built, \c uic will create a header file that lets us |
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71 construct the form. |
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72 |
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73 \section1 CalculatorForm Class Definition |
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74 |
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75 The \c CalculatorForm class uses the user interface described in the |
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76 \c calculatorform.ui file. To access the form and its contents, we need |
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77 to include the \c ui_calculatorform.h header file created by \c uic |
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78 during the build process: |
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79 |
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80 \snippet examples/designer/calculatorform/calculatorform.h 0 |
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81 |
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82 We define the \c CalculatorForm class by subclassing QWidget because the |
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83 form itself is based on QWidget: |
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84 |
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85 \snippet examples/designer/calculatorform/calculatorform.h 1 |
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86 |
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87 Apart from the constructor, the class contains two private slots that |
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88 are named according to the auto-connection naming convention required |
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89 by \c uic. |
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90 The private \c ui member variable refers to the form, and is used to |
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91 access the contents of the user interface. |
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92 |
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93 \section1 CalculatorForm Class Implementation |
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94 |
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95 The constructor simply calls the base class's constructor and |
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96 sets up the form's user interface. |
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97 |
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98 \snippet examples/designer/calculatorform/calculatorform.cpp 0 |
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99 |
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100 The user interface is set up with the \c setupUI() function. We pass |
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101 \c this as the argument to this function to use the \c CalculatorForm |
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102 widget itself as the container for the user interface. |
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103 |
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104 To automatically connect signals from the spin boxes defined in the |
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105 user interface, we use the naming convention that indicates which |
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106 widgets and their signals in the user interface should be connected |
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107 to each slot. The first slot is called whenever the spin box called |
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108 "inputSpinBox1" in the user interface emits the |
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109 \l{QSpinBox::valueChanged()}{valueChanged()} signal: |
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110 |
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111 \snippet examples/designer/calculatorform/calculatorform.cpp 1 |
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112 |
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113 When this occurs, we use the value supplied by the signal to update the |
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114 output label by setting its new text directly. We access the output label |
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115 and the other spin box via the class's private \c ui variable. |
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116 |
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117 The second slot is called whenever the second spin box, called |
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118 "inputSpinBox2", emits the \l{QSpinBox::valueChanged()}{valueChanged()} |
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119 signal: |
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120 |
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121 \snippet examples/designer/calculatorform/calculatorform.cpp 2 |
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122 |
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123 In this case, the value from the first spin box is read and combined |
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124 with the value supplied by the signal. Again, the output label is |
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125 updated directly via the \c ui variable. |
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126 */ |