| 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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| 19 | ** Foundation and appearing in the file included in the packaging of this
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| 20 | ** file.
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| 21 | **
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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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| 25 | **
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| 26 | ****************************************************************************/
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| 27 |
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| 28 | /*!
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| 29 | \example painting/imagecomposition
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| 30 | \title Image Composition Example
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| 31 |
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| 32 | The Image Composition example lets the user combine images
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| 33 | together using any composition mode supported by QPainter, described
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| 34 | in detail in \l{QPainter#Composition Modes}{Composition Modes}.
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| 35 |
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| 36 | \image imagecomposition-example.png
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| 37 |
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| 38 | \section1 Setting Up The Resource File
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| 39 |
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| 40 | The Image Composition example requires two source images,
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| 41 | \e butterfly.png and \e checker.png that are embedded within
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| 42 | \e imagecomposition.qrc. The file contains the following code:
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| 43 |
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| 44 | \quotefile examples/painting/imagecomposition/imagecomposition.qrc
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| 45 |
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| 46 | For more information on resource files, see \l{The Qt Resource System}.
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| 47 |
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| 48 | \section1 ImageComposer Class Definition
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| 49 |
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| 50 | The \c ImageComposer class is a subclass of QWidget that implements three
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| 51 | private slots, \c chooseSource(), \c chooseDestination(), and
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| 52 | \c recalculateResult().
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| 53 |
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| 54 | \snippet examples/painting/imagecomposition/imagecomposer.h 0
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| 55 |
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| 56 | In addition, \c ImageComposer consists of five private functions,
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| 57 | \c addOp(), \c chooseImage(), \c loadImage(), \c currentMode(), and
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| 58 | \c imagePos(), as well as private instances of QToolButton, QComboBox,
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| 59 | QLabel, and QImage.
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| 60 |
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| 61 | \snippet examples/painting/imagecomposition/imagecomposer.h 1
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| 62 |
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| 63 | \section1 ImageComposer Class Implementation
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| 64 |
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| 65 | We declare a QSize object, \c resultSize, as a static constant with width
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| 66 | and height equal to 200.
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| 67 |
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| 68 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 0
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| 69 |
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| 70 | Within the constructor, we instantiate a QToolButton object,
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| 71 | \c sourceButton and set its \l{QAbstractButton::setIconSize()}{iconSize}
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| 72 | property to \c resultSize. The \c operatorComboBox is instantiated and
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| 73 | then populated using the \c addOp() function. This function accepts a
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| 74 | QPainter::CompositionMode, \a mode, and a QString, \a name, representing
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| 75 | the name of the composition mode.
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| 76 |
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| 77 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 1
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| 78 |
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| 79 | The \c destinationButton is instantiated and its
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| 80 | \l{QAbstractButton::setIconSize()}{iconSize} property is set to
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| 81 | \c resultSize as well. The \l{QLabel}s \c equalLabel and \c resultLabel
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| 82 | are created and \c{resultLabel}'s \l{QWidget::setMinimumWidth()}
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| 83 | {minimumWidth} is set.
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| 84 |
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| 85 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 2
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| 86 |
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| 87 | We connect the following signals to their corresponding slots:
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| 88 | \list
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| 89 | \o \c{sourceButton}'s \l{QPushButton::clicked()}{clicked()} signal is
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| 90 | connected to \c chooseSource(),
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| 91 | \o \c{operatorComboBox}'s \l{QComboBox::activated()}{activated()}
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| 92 | signal is connected to \c recalculateResult(), and
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| 93 | \o \c{destinationButton}'s \l{QToolButton::clicked()}{clicked()} signal
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| 94 | is connected to \c chooseDestination().
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| 95 | \endlist
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| 96 |
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| 97 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 3
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| 98 |
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| 99 | A QGridLayout, \c mainLayout, is used to place all the widgets. Note
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| 100 | that \c{mainLayout}'s \l{QLayout::setSizeConstraint()}{sizeConstraint}
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| 101 | property is set to QLayout::SetFixedSize, which means that
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| 102 | \c{ImageComposer}'s size cannot be resized at all.
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| 103 |
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| 104 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 4
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| 105 |
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| 106 | We create a QImage, \c resultImage, and we invoke \c loadImage() twice
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| 107 | to load both the image files in our \e imagecomposition.qrc file. Then,
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| 108 | we set the \l{QWidget::setWindowTitle()}{windowTitle} property to
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| 109 | "Image Composition".
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| 110 |
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| 111 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 5
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| 112 |
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| 113 | The \c chooseSource() and \c chooseDestination() functions are
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| 114 | convenience functions that invoke \c chooseImage() with specific
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| 115 | parameters.
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| 116 |
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| 117 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 6
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| 118 | \codeline
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| 119 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 7
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| 120 |
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| 121 | The \c chooseImage() function loads an image of the user's choice,
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| 122 | depending on the \a title, \a image, and \a button.
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| 123 |
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| 124 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 10
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| 125 |
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| 126 | The \c recalculateResult() function is used to calculate amd display the
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| 127 | result of combining the two images together with the user's choice of
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| 128 | composition mode.
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| 129 |
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| 130 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 8
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| 131 |
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| 132 | The \c addOp() function adds an item to the \c operatorComboBox using
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| 133 | \l{QComboBox}'s \l{QComboBox::addItem()}{addItem} function. This function
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| 134 | accepts a QPainter::CompositionMode, \a mode, and a QString, \a name. The
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| 135 | rectangle is filled with Qt::Transparent and both the \c sourceImage and
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| 136 | \c destinationImage are painted, before displaying it on \c resultLabel.
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| 137 |
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| 138 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 9
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| 139 |
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| 140 | The \c loadImage() function paints a transparent background using
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| 141 | \l{QPainter::fillRect()}{fillRect()} and draws \c image in a
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| 142 | centralized position using \l{QPainter::drawImage()}{drawImage()}.
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| 143 | This \c image is then set as the \c{button}'s icon.
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| 144 |
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| 145 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 11
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| 146 |
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| 147 | The \c currentMode() function returns the composition mode currently
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| 148 | selected in \c operatorComboBox.
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| 149 |
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| 150 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 12
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| 151 |
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| 152 | We use the \c imagePos() function to ensure that images loaded onto the
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| 153 | QToolButton objects, \c sourceButton and \c destinationButton, are
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| 154 | centralized.
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| 155 |
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| 156 | \snippet examples/painting/imagecomposition/imagecomposer.cpp 13
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| 157 |
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| 158 | \section1 The \c main() Function
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| 159 |
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| 160 | The \c main() function instantiates QApplication and \c ImageComposer
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| 161 | and invokes its \l{QWidget::show()}{show()} function.
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| 162 |
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| 163 | \snippet examples/painting/imagecomposition/main.cpp 0
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| 164 |
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| 165 | */
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