source: trunk/doc/src/examples/calculatorbuilder.qdoc

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1/****************************************************************************
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3** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
4** All rights reserved.
5** Contact: Nokia Corporation ([email protected])
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16** GNU Free Documentation License
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27
28/*!
29 \example designer/calculatorbuilder
30 \title Calculator Builder Example
31
32 The Calculator Builder example shows how to create a user interface from
33 a \QD form at run-time, using the QUiLoader class.
34
35 \image calculatorbuilder-example.png
36
37 We use the form created in the \l{designer/calculatorform}{Calculator Form}
38 example to show that the same user interface can be generated when the
39 application is executed or defined when the application is built.
40
41 \section1 Preparation
42
43 The \l{designer/calculatorform}{Calculator Form} example defines a user
44 interface that we can use without modification. In this example, we use a
45 \l{The Qt Resource System}{resource file} to contain the \c{calculatorform.ui}
46 file created in the previous example, but it could be stored on disk instead.
47
48 To generate a form at run time, we need to link the example against the
49 \c QtUiTools module library. The project file we use contains all the
50 necessary information to do this:
51
52 \snippet examples/designer/calculatorbuilder/calculatorbuilder.pro 0
53
54 All the other necessary files are declared as usual.
55
56 \section1 CalculatorForm Class Definition
57
58 The \c CalculatorForm class defines the widget used to host the form's
59 user interface:
60
61 \snippet examples/designer/calculatorbuilder/calculatorform.h 0
62
63 Note that we do not need to include a header file to describe the user
64 interface. We only define two public slots, using the auto-connection
65 naming convention required by \c uic, and declare private variables
66 that we will use to access widgets provided by the form after they are
67 constructed.
68
69 \section1 CalculatorForm Class Implementation
70
71 We will need to use the QUiLoader class that is provided by the
72 \c libQtUiTools library, so we first ensure that we include the header
73 file for the module:
74
75 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 0
76
77 The constructor uses a form loader object to construct the user
78 interface that we retrieve, via a QFile object, from the example's
79 resources:
80
81 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 1
82
83 By including the user interface in the example's resources, we ensure
84 that it will be present when the example is run. The \c{loader.load()}
85 function takes the user interface description contained in the file
86 and constructs the form widget as a child widget of the \c{CalculatorForm}.
87
88 We are interested in three widgets in the generated user interface:
89 two spin boxes and a label. For convenience, we retrieve pointers to
90 these widgets from the widget that was constructed by the \c FormBuilder,
91 and we record them for later use. The \c qFindChild() template function
92 allows us to query widgets in order to find named child widgets.
93
94 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 2
95
96 The widgets created by the form loader need to be connected to the
97 specially-named slots in the \c CalculatorForm object. We use Qt's
98 meta-object system to enable these connections:
99
100 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 3
101
102 The form widget is added to a layout, and the window title is set:
103
104 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 4
105
106 The two slots that modify widgets provided by the form are defined
107 in a similar way to those in the \l{designer/calculatorform}{Calculator
108 Form} example, except that we read the values from the spin boxes and
109 write the result to the output widget via the pointers we recorded in
110 the constructor:
111
112 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 5
113 \codeline
114 \snippet examples/designer/calculatorbuilder/calculatorform.cpp 7
115
116 The advantage of this approach is that we can replace the form when the
117 application is run, but we can still manipulate the widgets it contains
118 as long as they are given appropriate names.
119*/
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