| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation ([email protected])
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| 6 | **
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| 7 | ** This file is part of the documentation of the Qt Toolkit.
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| 8 | **
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| 9 | ** $QT_BEGIN_LICENSE:FDL$
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| 10 | ** Commercial Usage
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| 11 | ** Licensees holding valid Qt Commercial licenses may use this file in
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| 12 | ** accordance with the Qt Commercial License Agreement provided with the
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| 13 | ** Software or, alternatively, in accordance with the terms contained in a
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| 14 | ** written agreement between you and Nokia.
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| 15 | **
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| 16 | ** GNU Free Documentation License
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| 17 | ** Alternatively, this file may be used under the terms of the GNU Free
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| 18 | ** Documentation License version 1.3 as published by the Free Software
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| 20 | ** file.
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| 22 | ** If you have questions regarding the use of this file, please contact
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| 23 | ** Nokia at [email protected].
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| 24 | ** $QT_END_LICENSE$
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| 26 | ****************************************************************************/
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| 27 |
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| 28 | /*!
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| 29 | \example gestures/imagegestures
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| 30 | \title Image Gestures Example
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| 31 |
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| 32 | This example shows how to enable gestures for a widget and use gesture input
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| 33 | to perform actions.
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| 34 |
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| 35 | We use two classes to create the user interface for the application: \c MainWidget
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| 36 | and \c ImageWidget. The \c MainWidget class is simply used as a container for the
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| 37 | \c ImageWidget class, which we will configure to accept gesture input. Since we
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| 38 | are interested in the way gestures are used, we will concentrate on the
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| 39 | implementation of the \c ImageWidget class.
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| 40 |
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| 41 | \section1 ImageWidget Class Definition
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| 42 |
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| 43 | The \c ImageWidget class is a simple QWidget subclass that reimplements the general
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| 44 | QWidget::event() handler function in addition to several more specific event handlers:
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| 45 |
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| 46 | \snippet examples/gestures/imagegestures/imagewidget.h class definition begin
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| 47 | \dots
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| 48 | \snippet examples/gestures/imagegestures/imagewidget.h class definition end
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| 49 |
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| 50 | We also implement a private helper function, \c gestureEvent(), to help manage
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| 51 | gesture events delivered to the widget, and three functions to perform actions
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| 52 | based on gestures: \c panTriggered(), \c pinchTriggered() and \c swipeTriggered().
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| 53 |
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| 54 | \section1 ImageWidget Class Implementation
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| 55 |
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| 56 | In the widget's constructor, we begin by setting up various parameters that will
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| 57 | be used to control the way images are displayed.
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| 58 |
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| 59 | \snippet examples/gestures/imagegestures/imagewidget.cpp constructor
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| 60 |
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| 61 | We enable three of the standard gestures for the widget by calling QWidget::grabGesture()
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| 62 | with the types of gesture we need. These will be recognized by the application's
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| 63 | default gesture recognizer, and events will be delivered to our widget.
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| 64 |
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| 65 | Since QWidget does not define a specific event handler for gestures, the widget
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| 66 | needs to reimplement the general QWidget::event() to receive gesture events.
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| 67 |
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