Move icons example to manual test
Change-Id: I08f44448f96a61f780c21d628954879c7b28dce3
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit c3fd8e911e
)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
@ -1,805 +0,0 @@
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// Copyright (C) 2016 The Qt Company Ltd.
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// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
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/*!
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\example widgets/icons
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\title Icons Example
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\ingroup examples-widgets
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\brief The Icons example shows how QIcon can generate pixmaps reflecting
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an icon's state, mode and size.
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These pixmaps are generated from the set of pixmaps made available to the
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icon, and are used by Qt widgets to show an icon representing a particular
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action.
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\image icons-example.png Screenshot of the Icons example
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Contents:
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\tableofcontents
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\section1 QIcon Overview
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The QIcon class provides scalable icons in different modes and
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states. An icon's state and mode are depending on the intended use
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of the icon. Qt currently defines four modes:
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\table
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\header \li Mode \li Description
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\row
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\li QIcon::Normal
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\li Display the pixmap when the user is not interacting with the
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icon, but the functionality represented by the icon is
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available.
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\row
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\li QIcon::Active
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\li Display the pixmap when the functionality represented by the
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icon is available and the user is interacting with the icon,
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for example, moving the mouse over it or clicking it.
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\row
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\li QIcon::Disabled
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\li Display the pixmap when the functionality represented by
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the icon is not available.
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\row
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\li QIcon::Selected
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\li Display the pixmap when the icon is selected.
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\endtable
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QIcon's states are QIcon::On and QIcon::Off, which will display
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the pixmap when the widget is in the respective state. The most
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common usage of QIcon's states are when displaying checkable tool
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buttons or menu entries (see QAbstractButton::setCheckable() and
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QAction::setCheckable()). When a tool button or menu entry is
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checked, the QIcon's state is \l{QIcon::}{On}, otherwise it's
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\l{QIcon::}{Off}. You can, for example, use the QIcon's states to
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display differing pixmaps depending on whether the tool button or
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menu entry is checked or not.
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A QIcon can generate smaller, larger, active, disabled, and
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selected pixmaps from the set of pixmaps it is given. Such
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pixmaps are used by Qt widgets to show an icon representing a
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particular action.
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\section1 Overview of the Icons Application
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With the Icons application you get a preview of an icon's
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generated pixmaps reflecting its different states, modes and size.
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When an image is loaded into the application, it is converted into
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a pixmap and becomes a part of the set of pixmaps available to the
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icon. An image can be excluded from this set by checking off the
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related checkbox. The application provides a sub directory
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containing sets of images explicitly designed to illustrate how Qt
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renders an icon in different modes and states.
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The application allows you to manipulate the icon size with some
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predefined sizes and a spin box. The predefined sizes are style
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dependent, but most of the styles have the same values. Only the
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\macos style differs by using 32 pixels instead of 16 pixels
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for toolbar buttons. You can navigate between the available styles
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using the \uicontrol View menu.
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\image icons-view-menu.png Screenshot of the View menu
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The \uicontrol View menu also provide the option to make the application
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guess the icon state and mode from an image's file name. The \uicontrol
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File menu provide the options of adding an image and removing all
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images. These last options are also available through a context
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menu that appears if you press the right mouse button within the
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table of image files. In addition, the \uicontrol File menu provide an
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\uicontrol Exit option, and the \uicontrol Help menu provide information about
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the example and about Qt.
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\image icons_find_normal.png Screenshot of the Find Files
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The screenshot above shows the application with one image file
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loaded. The \uicontrol {Guess Image Mode/State} is enabled and the
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style is Plastique.
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When QIcon is provided with only one available pixmap, that
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pixmap is used for all the states and modes. In this case the
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pixmap's icon mode is set to normal, and the generated pixmaps
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for the normal and active modes will look the same. But in
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disabled and selected mode, Qt will generate a slightly different
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pixmap.
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The next screenshot shows the application with an additional file
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loaded, providing QIcon with two available pixmaps. Note that the
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new image file's mode is set to disabled. When rendering the \uicontrol
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Disabled mode pixmaps, Qt will now use the new image. We can see
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the difference: The generated disabled pixmap in the first
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screenshot is slightly darker than the pixmap with the originally
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set disabled mode in the second screenshot.
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\image icons_find_normal_disabled.png Screenshot of the Find Files
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When Qt renders the icon's pixmaps it searches through the set of
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available pixmaps following a particular algorithm. The algorithm
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is documented in QIcon, but we will describe some particular cases
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below.
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\image icons_monkey_active.png Screenshot of the Find Files
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In the screenshot above, we have set \c monkey_on_32x32 to be an
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Active/On pixmap and \c monkey_off_64x64 to be Normal/Off. To
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render the other six mode/state combinations, QIcon uses the
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search algorithm described in the table below:
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\table 100%
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\header \li{2,1} Requested Pixmap \li {8,1} Preferred Alternatives (mode/state)
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\header \li Mode \li State \li 1 \li 2 \li 3 \li 4 \li 5 \li 6 \li 7 \li 8
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\row \li{1,2} Normal \li Off \li \b N0 \li A0 \li N1 \li A1 \li D0 \li S0 \li D1 \li S1
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\row \li On \li N1 \li \b A1 \li N0 \li A0 \li D1 \li S1 \li D0 \li S0
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\row \li{1,2} Active \li Off \li A0 \li \b N0 \li A1 \li N1 \li D0 \li S0 \li D1 \li S1
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\row \li On \li \b A1 \li N1 \li A0 \li N0 \li D1 \li S1 \li D0 \li S0
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\row \li{1,2} Disabled \li Off \li D0 \li \b {N0'} \li A0' \li D1 \li N1' \li A1' \li S0' \li S1'
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\row \li On \li D1 \li N1' \li \b {A1'} \li D0 \li N0' \li A0' \li S1' \li S0'
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\row \li{1,2} Selected \li Off \li S0 \li \b {N0''} \li A0'' \li S1 \li N1'' \li A1'' \li D0'' \li D1''
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\row \li On \li S1 \li N1'' \li \b {A1''} \li S0 \li N0'' \li A0'' \li D1'' \li D0''
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\endtable
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In the table, "0" and "1" stand for "Off" and "On", respectively.
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Single quotes indicates that QIcon generates a disabled ("grayed
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out") version of the pixmap; similarly, double quuote indicate
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that QIcon generates a selected ("blued out") version of the
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pixmap.
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The alternatives used in the screenshot above are shown in bold.
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For example, the Disabled/Off pixmap is derived by graying out
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the Normal/Off pixmap (\c monkey_off_64x64).
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In the next screenshots, we loaded the whole set of monkey
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images. By checking or unchecking file names from the image list,
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we get different results:
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\table
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\row
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\li \inlineimage icons_monkey.png Screenshot of the Monkey Files
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\li \inlineimage icons_monkey_mess.png Screenshot of the Monkey Files
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\endtable
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For any given mode/state combination, it is possible to specify
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several images at different resolutions. When rendering an
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icon, QIcon will automatically pick the most suitable image
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and scale it down if necessary. (QIcon never scales up images,
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because this rarely looks good.)
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The screenshots below shows what happens when we provide QIcon
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with three images (\c qt_extended_16x16.png, \c qt_extended_32x32.png, \c
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qt_extended_48x48.png) and try to render the QIcon at various
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resolutions:
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\table
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\row
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\li
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\li \inlineimage icons_qt_extended_8x8.png Qt Extended icon at 8 x 8
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\li \inlineimage icons_qt_extended_16x16.png Qt Extended icon at 16 x 16
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\li \inlineimage icons_qt_extended_17x17.png Qt Extended icon at 17 x 17
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\row
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\li
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\li 8 x 8
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\li \b {16 x 16}
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\li 17 x 17
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\row
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\li \inlineimage icons_qt_extended_32x32.png Qt Extended icon at 32 x 32
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\li \inlineimage icons_qt_extended_33x33.png Qt Extended icon at 33 x 33
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\li \inlineimage icons_qt_extended_48x48.png Qt Extended icon at 48 x 48
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\li \inlineimage icons_qt_extended_64x64.png Qt Extended icon at 64 x 64
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\row
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\li \b {32 x 32}
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\li 33 x 33
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\li \b {48 x 48}
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\li 64 x 64
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\endtable
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For sizes up to 16 x 16, QIcon uses \c qt_extended_16x16.png and
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scales it down if necessary. For sizes between 17 x 17 and 32 x
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32, it uses \c qt_extended_32x32.png. For sizes above 32 x 32, it uses
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\c qt_extended_48x48.png.
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\section1 Line-by-Line Walkthrough
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The Icons example consists of four classes:
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\list
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\li \c MainWindow inherits QMainWindow and is the main application
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window.
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\li \c IconPreviewArea is a custom widget that displays all
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combinations of states and modes for a given icon.
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\li \c IconSizeSpinBox is a subclass of QSpinBox that lets the
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user enter icon sizes (e.g., "48 x 48").
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\li \c ImageDelegate is a subclass of QStyledItemDelegate that
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provides comboboxes for letting the user set the mode and state
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associated with an image.
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\endlist
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We will start by reviewing the \c IconPreviewArea class before we
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take a look at the \c MainWindow class. Finally, we will review the
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\c IconSizeSpinBox and \c ImageDelegate classes.
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\section2 IconPreviewArea Class Definition
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An \c IconPreviewArea widget consists of a group box containing a grid of
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QLabel widgets displaying headers and pixmaps.
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\image icons_preview_area.png Screenshot of IconPreviewArea.
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\snippet widgets/icons/iconpreviewarea.h 0
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The \c IconPreviewArea class inherits QWidget. It displays the
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generated pixmaps corresponding to an icon's possible states and
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modes at a given size.
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\snippet widgets/icons/iconpreviewarea.cpp 42
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We would like the table columns to be in the order QIcon::Normal,
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QIcon::Active, QIcon::Disabled, QIcon::Selected and the rows in the order
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QIcon::Off, QIcon::On, which does not match the enumeration. The above code
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provides arrays allowing to map from enumeration value to row/column
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(by using QList::indexOf()) and back by using the array index and lists
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of the matching strings. Qt's containers can be easily populated by
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using C++ 11 initializer lists.
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We need two public functions to set the current icon and the
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icon's size. In addition the class has three private functions: We
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use the \c createHeaderLabel() and \c createPixmapLabel()
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functions when constructing the preview area, and we need the \c
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updatePixmapLabels() function to update the preview area when
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the icon or the icon's size has changed.
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The \c NumModes and \c NumStates constants reflect \l{QIcon}'s
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number of currently defined modes and states.
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\section2 IconPreviewArea Class Implementation
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\snippet widgets/icons/iconpreviewarea.cpp 0
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In the constructor we create the labels displaying the headers and
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the icon's generated pixmaps, and add them to a grid layout.
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When creating the header labels, we make sure the enums \c
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NumModes and \c NumStates defined in the \c .h file, correspond
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with the number of labels that we create. Then if the enums at
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some point are changed, the \c Q_ASSERT() macro will alert that this
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part of the \c .cpp file needs to be updated as well.
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If the application is built in debug mode, the \c Q_ASSERT()
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macro will expand to
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\code
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if (!condition)
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qFatal("ASSERT: "condition" in file ...");
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\endcode
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In release mode, the macro simply disappear. The mode can be set
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in the application's \c .pro file. One way to do so is to add an
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option to \c qmake when building the application:
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\code
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qmake "CONFIG += debug" icons.pro
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\endcode
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or
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\code
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qmake "CONFIG += release" icons.pro
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\endcode
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Another approach is to add this line directly to the \c .pro
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file.
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\snippet widgets/icons/iconpreviewarea.cpp 1
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\codeline
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\snippet widgets/icons/iconpreviewarea.cpp 2
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The public \c setIcon() and \c setSize() functions change the icon
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or the icon size, and make sure that the generated pixmaps are
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updated.
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\snippet widgets/icons/iconpreviewarea.cpp 3
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\codeline
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\snippet widgets/icons/iconpreviewarea.cpp 4
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We use the \c createHeaderLabel() and \c createPixmapLabel()
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functions to create the preview area's labels displaying the
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headers and the icon's generated pixmaps. Both functions return
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the QLabel that is created.
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\snippet widgets/icons/iconpreviewarea.cpp 5
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We use the private \c updatePixmapLabel() function to update the
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generated pixmaps displayed in the preview area.
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For each mode, and for each state, we retrieve a pixmap using the
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QIcon::pixmap() function, which generates a pixmap corresponding
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to the given state, mode and size. We pass the QWindows instance
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obtained by calling QWidget::windowHandle() on the top level
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widget (QWidget::nativeParentWidget()) in order to retrieve
|
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the pixmap that matches best.
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We format a tooltip displaying size, actual size and device pixel
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ratio.
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\section2 MainWindow Class Definition
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The \c MainWindow widget consists of three main elements: an
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images group box, an icon size group box and a preview area.
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\image icons-example.png Screenshot of the Icons example
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\snippet widgets/icons/mainwindow.h 0
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The MainWindow class inherits from QMainWindow. We reimplement the
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constructor, and declare several private slots:
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\list
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\li The \c about() slot simply provides information about the example.
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\li The \c changeStyle() slot changes the application's GUI style and
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adjust the style dependent size options.
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\li The \c changeSize() slot changes the size of the preview area's icon.
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\li The \c changeIcon() slot updates the set of pixmaps available to the
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icon displayed in the preview area.
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\li The \c addSampleImages() slot allows the user to load a new image
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from the samples provided into the application.
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\li The \c addOtherImages() slot allows the user to load a new image from
|
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the directory obtained by calling
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QStandardPaths::standardLocations(QStandardPaths::PicturesLocation).
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\li The \c screenChanged() updates the display in the \uicontrol{High DPI}
|
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group box to correctly display the parameters of the current screen
|
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the window is located on.
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\endlist
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In addition we declare several private functions to simplify the
|
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constructor.
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\section2 MainWindow Class Implementation
|
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|
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\snippet widgets/icons/mainwindow.cpp 0
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|
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In the constructor we first create the main window's central
|
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widget and its child widgets, and put them in a grid layout. Then
|
||||
we create the menus with their associated entries and actions.
|
||||
|
||||
We set the window title and determine the current style for the
|
||||
application. We also enable the icon size spin box by clicking the
|
||||
associated radio button, making the current value of the spin box
|
||||
the icon's initial size.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 1
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||||
|
||||
The \c about() slot displays a message box using the static
|
||||
QMessageBox::about() function. In this example it displays a
|
||||
simple box with information about the example.
|
||||
|
||||
The \c about() function looks for a suitable icon in four
|
||||
locations: It prefers its parent's icon if that exists. If it
|
||||
doesn't, the function tries the top-level widget containing
|
||||
parent, and if that fails, it tries the active window. As a last
|
||||
resort it uses the QMessageBox's Information icon.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 2
|
||||
|
||||
In the \c changeStyle() slot we first check the slot's
|
||||
parameter. If it is false we immediately return, otherwise we find
|
||||
out which style to change to, i.e. which action that triggered the
|
||||
slot, using the QObject::sender() function.
|
||||
|
||||
This function returns the sender as a QObject pointer. Since we
|
||||
know that the sender is a QAction object, we can safely cast the
|
||||
QObject. We could have used a C-style cast or a C++ \c
|
||||
static_cast(), but as a defensive programming technique we use a
|
||||
\l qobject_cast(). The advantage is that if the object has the
|
||||
wrong type, a null pointer is returned. Crashes due to null
|
||||
pointers are much easier to diagnose than crashes due to unsafe
|
||||
casts.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 3
|
||||
\snippet widgets/icons/mainwindow.cpp 4
|
||||
|
||||
Once we have the action, we extract the style name using
|
||||
QAction::data(). Then we create a QStyle object using the static
|
||||
QStyleFactory::create() function.
|
||||
|
||||
Although we can assume that the style is supported by the
|
||||
QStyleFactory: To be on the safe side, we use the \c Q_ASSERT()
|
||||
macro to check if the created style is valid before we use the
|
||||
QApplication::setStyle() function to set the application's GUI
|
||||
style to the new style. QApplication will automatically delete
|
||||
the style object when a new style is set or when the application
|
||||
exits.
|
||||
|
||||
The predefined icon size options provided in the application are
|
||||
style dependent, so we need to update the labels in the icon size
|
||||
group box and in the end call the \c changeSize() slot to update
|
||||
the icon's size.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 5
|
||||
|
||||
The \c changeSize() slot sets the size for the preview area's
|
||||
icon.
|
||||
|
||||
It is invoked by the QButtonGroup whose members are radio buttons for
|
||||
controlling the icon size. In \c createIconSizeGroupBox(), each button is
|
||||
assigned a QStyle::PixelMetric value as an id, which is passed as a
|
||||
parameter to the slot.
|
||||
|
||||
The special value \c OtherSize indicates that the spin box is
|
||||
enabled. If it is, we extract the extent of the new size from the
|
||||
box. If it's not, we query the style for the metric. Then we create
|
||||
a QSize object based on the extent, and use that object to set the
|
||||
size of the preview area's icon.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 12
|
||||
|
||||
The function \c addImages() is called by the slot addSampleImages()
|
||||
passing the samples directory, or by the slot addOtherImages()
|
||||
passing the directory obtained by querying
|
||||
QStandardPaths::standardLocations().
|
||||
|
||||
The first thing we do is to show a file dialog to the user.
|
||||
We initialize it to show the filters returned by
|
||||
QImageReader::supportedMimeTypes().
|
||||
|
||||
For each of the files the file dialog returns, we add a row to the
|
||||
table widget. The table widget is listing the images the user has
|
||||
loaded into the application.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 13
|
||||
|
||||
We retrieve the image name using the QFileInfo::baseName()
|
||||
function that returns the base name of the file without the path,
|
||||
and create the first table widget item in the row.
|
||||
We check if a high resolution version of the image exists (identified by
|
||||
the suffix \c @2x on the base name) and display that along with the size
|
||||
in the tooltip.
|
||||
|
||||
We add the file's complete name to the item's data. Since an item can
|
||||
hold several information pieces, we need to assign the file name a role
|
||||
that will distinguish it from other data. This role can be Qt::UserRole
|
||||
or any value above it.
|
||||
|
||||
We also make sure that the item is not editable by removing the
|
||||
Qt::ItemIsEditable flag. Table items are editable by default.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 15
|
||||
|
||||
Then we create the second and third items in the row making the
|
||||
default mode Normal and the default state Off. But if the \uicontrol
|
||||
{Guess Image Mode/State} option is checked, and the file name
|
||||
contains "_act", "_dis", or "_sel", the modes are changed to
|
||||
Active, Disabled, or Selected. And if the file name contains
|
||||
"_on", the state is changed to On. The sample files in the
|
||||
example's \c images subdirectory respect this naming convention.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 18
|
||||
|
||||
In the end we add the items to the associated row, and use the
|
||||
QTableWidget::openPersistentEditor() function to create
|
||||
comboboxes for the mode and state columns of the items.
|
||||
|
||||
Due to the connection between the table widget's \l
|
||||
{QTableWidget::itemChanged()}{itemChanged()} signal and the \c
|
||||
changeIcon() slot, the new image is automatically converted into a
|
||||
pixmap and made part of the set of pixmaps available to the icon
|
||||
in the preview area. So, corresponding to this fact, we need to
|
||||
make sure that the new image's check box is enabled.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 6
|
||||
|
||||
The \c changeIcon() slot is called when the user alters the set
|
||||
of images listed in the QTableWidget, to update the QIcon object
|
||||
rendered by the \c IconPreviewArea.
|
||||
|
||||
We first create a QIcon object, and then we run through the
|
||||
QTableWidget, which lists the images the user has loaded into the
|
||||
application.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 8
|
||||
|
||||
We also extract the image file's name using the
|
||||
QTableWidgetItem::data() function. This function takes a
|
||||
Qt::DataItemRole as an argument to retrieve the right data
|
||||
(remember that an item can hold several pieces of information)
|
||||
and returns it as a QVariant. Then we use the
|
||||
QVariant::toString() function to get the file name as a QString.
|
||||
|
||||
To create a pixmap from the file, we need to first create an
|
||||
image and then convert this image into a pixmap using
|
||||
QPixmap::fromImage(). Once we have the final pixmap, we add it,
|
||||
with its associated mode and state, to the QIcon's set of
|
||||
available pixmaps.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 11
|
||||
|
||||
After running through the entire list of images, we change the
|
||||
icon of the preview area to the one we just created.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 20
|
||||
|
||||
In the \c removeAllImages() slot, we simply set the table widget's
|
||||
row count to zero, automatically removing all the images the user
|
||||
has loaded into the application. Then we update the set of pixmaps
|
||||
available to the preview area's icon using the \c changeIcon()
|
||||
slot.
|
||||
|
||||
\image icons_images_groupbox.png Screenshot of the images group box
|
||||
|
||||
The \c createImagesGroupBox() function is implemented to simplify
|
||||
the constructor. The main purpose of the function is to create a
|
||||
QTableWidget that will keep track of the images the user has
|
||||
loaded into the application.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 21
|
||||
|
||||
First we create a group box that will contain the table widget.
|
||||
Then we create a QTableWidget and customize it to suit our
|
||||
purposes.
|
||||
|
||||
We call QAbstractItemView::setSelectionMode() to prevent the user
|
||||
from selecting items.
|
||||
|
||||
The QAbstractItemView::setItemDelegate() call sets the item
|
||||
delegate for the table widget. We create a \c ImageDelegate that
|
||||
we make the item delegate for our view.
|
||||
|
||||
The QStyledItemDelegate class can be used to provide an editor for an item view
|
||||
class that is subclassed from QAbstractItemView. Using a delegate
|
||||
for this purpose allows the editing mechanism to be customized and
|
||||
developed independently from the model and view.
|
||||
|
||||
In this example we derive \c ImageDelegate from QStyledItemDelegate.
|
||||
QStyledItemDelegate usually provides line editors, while our subclass
|
||||
\c ImageDelegate, provides comboboxes for the mode and state
|
||||
fields.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 22
|
||||
|
||||
Then we customize the QTableWidget's horizontal header, and hide
|
||||
the vertical header.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 24
|
||||
|
||||
At the end, we connect the QTableWidget::itemChanged() signal to
|
||||
the \c changeIcon() slot to ensure that the preview area is in
|
||||
sync with the image table.
|
||||
|
||||
\image icons_size_groupbox.png Screenshot of the icon size group box
|
||||
|
||||
The \c createIconSizeGroupBox() function is called from the
|
||||
constructor. It creates the widgets controlling the size of the
|
||||
preview area's icon.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 26
|
||||
|
||||
First we create a group box that will contain all the widgets;
|
||||
then we create the radio buttons and the spin box. We add the
|
||||
radio buttons to an instance of QButtonGroup, using the value
|
||||
of the QStyle::PixelMetric they represent as an integer id.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 40
|
||||
|
||||
We introduce an enumeration constant \c OtherSize to represent
|
||||
a custom size.
|
||||
|
||||
The spin box is not a regular QSpinBox but an \c IconSizeSpinBox.
|
||||
The \c IconSizeSpinBox class inherits QSpinBox and reimplements
|
||||
two functions: QSpinBox::textFromValue() and
|
||||
QSpinBox::valueFromText(). The \c IconSizeSpinBox is designed to
|
||||
handle icon sizes, e.g., "32 x 32", instead of plain integer
|
||||
values.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 27
|
||||
|
||||
Then we connect all of the radio buttons
|
||||
\l{QRadioButton::toggled()}{toggled()} signals and the spin box's
|
||||
\l {QSpinBox::valueChanged()}{valueChanged()} signal to the \c
|
||||
changeSize() slot to make sure that the size of the preview
|
||||
area's icon is updated whenever the user changes the icon size.
|
||||
In the end we put the widgets in a layout that we install on the
|
||||
group box.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 28
|
||||
|
||||
In the \c createActions() function we create and customize all the
|
||||
actions needed to implement the functionality associated with the
|
||||
menu entries in the application.
|
||||
|
||||
In particular we create the \c styleActionGroup based on the
|
||||
currently available GUI styles using
|
||||
QStyleFactory. QStyleFactory::keys() returns a list of valid keys,
|
||||
typically including "windows" and "fusion". Depending on the platform,
|
||||
"windowsvista" and "macos" may be available.
|
||||
|
||||
We create one action for each key, and adds the action to the
|
||||
action group. Also, for each action, we call QAction::setData()
|
||||
with the style name. We will retrieve it later using
|
||||
QAction::data().
|
||||
|
||||
As we go along, we create the \uicontrol File, \uicontrol View and
|
||||
\uicontrol Help menus and add the actions to them.
|
||||
|
||||
The QMenu class provides a menu widget for use in menu bars,
|
||||
context menus, and other popup menus. We put each menu in the
|
||||
application's menu bar, which we retrieve using
|
||||
QMainWindow::menuBar().
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 30
|
||||
|
||||
QWidgets have a \l{QWidget::contextMenuPolicy}{contextMenuPolicy}
|
||||
property that controls how the widget should behave when the user
|
||||
requests a context menu (e.g., by right-clicking). We set the
|
||||
QTableWidget's context menu policy to Qt::ActionsContextMenu,
|
||||
meaning that the \l{QAction}s associated with the widget should
|
||||
appear in its context menu.
|
||||
|
||||
Then we add the \uicontrol{Add Image} and \uicontrol{Remove All Images}
|
||||
actions to the table widget. They will then appear in the table
|
||||
widget's context menu.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 31
|
||||
|
||||
In the \c checkCurrentStyle() function we go through the group of
|
||||
style actions, looking for the current GUI style.
|
||||
|
||||
For each action, we first extract the style name using
|
||||
QAction::data(). Since this is only a QStyleFactory key (e.g.,
|
||||
"macos"), we cannot compare it directly to the current
|
||||
style's class name. We need to create a QStyle object using the
|
||||
static QStyleFactory::create() function and compare the class
|
||||
name of the created QStyle object with that of the current style.
|
||||
As soon as we are done with a QStyle candidate, we delete it.
|
||||
|
||||
For all QObject subclasses that use the \c Q_OBJECT macro, the
|
||||
class name of an object is available through its
|
||||
\l{QObject::metaObject()}{meta-object}.
|
||||
|
||||
We can assume that the style is supported by
|
||||
QStyleFactory, but to be on the safe side we use the \c
|
||||
Q_ASSERT() macro to make sure that QStyleFactory::create()
|
||||
returned a valid pointer.
|
||||
|
||||
\snippet widgets/icons/mainwindow.cpp 44
|
||||
|
||||
We overload the show() function to set up the updating of the
|
||||
current screen in \c screenChanged(). After calling QWidget::show(),
|
||||
the QWindow associated with the QWidget is created and we can
|
||||
connect to its QWindow::screenChanged() signal.
|
||||
|
||||
\section2 IconSizeSpinBox Class Definition
|
||||
|
||||
\snippet widgets/icons/iconsizespinbox.h 0
|
||||
|
||||
The \c IconSizeSpinBox class is a subclass of QSpinBox. A plain
|
||||
QSpinBox can only handle integers. But since we want to display
|
||||
the spin box's values in a more sophisticated way, we need to
|
||||
subclass QSpinBox and reimplement the QSpinBox::textFromValue()
|
||||
and QSpinBox::valueFromText() functions.
|
||||
|
||||
\image icons_size_spinbox.png Screenshot of the icon size spinbox
|
||||
|
||||
\section2 IconSizeSpinBox Class Implementation
|
||||
|
||||
\snippet widgets/icons/iconsizespinbox.cpp 0
|
||||
|
||||
The constructor is trivial.
|
||||
|
||||
\snippet widgets/icons/iconsizespinbox.cpp 2
|
||||
|
||||
QSpinBox::textFromValue() is used by the spin box whenever it
|
||||
needs to display a value. The default implementation returns a
|
||||
base 10 representation of the \c value parameter.
|
||||
|
||||
Our reimplementation returns a QString of the form "32 x 32".
|
||||
|
||||
\snippet widgets/icons/iconsizespinbox.cpp 1
|
||||
|
||||
The QSpinBox::valueFromText() function is used by the spin box
|
||||
whenever it needs to interpret text typed in by the user. Since
|
||||
we reimplement the \c textFromValue() function we also need to
|
||||
reimplement the \c valueFromText() function to interpret the
|
||||
parameter text and return the associated int value.
|
||||
|
||||
We parse the text using a regular expression (a QRegularExpression). We
|
||||
define an expression that matches one or several digits,
|
||||
optionally followed by whitespace, an "x" or the times symbol,
|
||||
whitespace and one or several digits again.
|
||||
|
||||
The first digits of the regular expression are captured using
|
||||
parentheses. This enables us to use the QRegularExpressionMatch::captured()
|
||||
or QRegularExpressionMatch::capturedTexts() functions to extract the matched
|
||||
characters. If the first and second numbers of the spin box value
|
||||
differ (e.g., "16 x 24"), we use the first number.
|
||||
|
||||
When the user presses \uicontrol Enter, QSpinBox first calls
|
||||
QSpinBox::valueFromText() to interpret the text typed by the
|
||||
user, then QSpinBox::textFromValue() to present it in a canonical
|
||||
format (e.g., "16 x 16").
|
||||
|
||||
\section2 ImageDelegate Class Definition
|
||||
|
||||
\snippet widgets/icons/imagedelegate.h 0
|
||||
|
||||
The \c ImageDelegate class is a subclass of QStyledItemDelegate. The
|
||||
QStyledItemDelegate class provides display and editing facilities for
|
||||
data items from a model. A single QStyledItemDelegate object is
|
||||
responsible for all items displayed in a item view (in our case,
|
||||
a QTableWidget).
|
||||
|
||||
A QStyledItemDelegate can be used to provide an editor for an item view
|
||||
class that is subclassed from QAbstractItemView. Using a delegate
|
||||
for this purpose allows the editing mechanism to be customized and
|
||||
developed independently from the model and view.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.h 1
|
||||
|
||||
The default implementation of QStyledItemDelegate creates a QLineEdit.
|
||||
Since we want the editor to be a QComboBox, we need to subclass
|
||||
QStyledItemDelegate and reimplement the QStyledItemDelegate::createEditor(),
|
||||
QStyledItemDelegate::setEditorData() and QStyledItemDelegate::setModelData()
|
||||
functions.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.h 2
|
||||
|
||||
The \c emitCommitData() slot is used to emit the
|
||||
QImageDelegate::commitData() signal with the appropriate
|
||||
argument.
|
||||
|
||||
\section2 ImageDelegate Class Implementation
|
||||
|
||||
\snippet widgets/icons/imagedelegate.cpp 0
|
||||
|
||||
The constructor is trivial.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.cpp 1
|
||||
|
||||
The default QStyledItemDelegate::createEditor() implementation returns
|
||||
the widget used to edit the item specified by the model and item
|
||||
index for editing. The parent widget and style option are used to
|
||||
control the appearance of the editor widget.
|
||||
|
||||
Our reimplementation creates and populates a combobox instead of
|
||||
the default line edit. The contents of the combobox depends on
|
||||
the column in the table for which the editor is requested. Column
|
||||
1 contains the QIcon modes, whereas column 2 contains the QIcon
|
||||
states.
|
||||
|
||||
In addition, we connect the combobox's \l
|
||||
{QComboBox::activated()}{activated()} signal to the \c
|
||||
emitCommitData() slot to emit the
|
||||
QAbstractItemDelegate::commitData() signal whenever the user
|
||||
chooses an item using the combobox. This ensures that the rest of
|
||||
the application notices the change and updates itself.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.cpp 2
|
||||
|
||||
The QStyledItemDelegate::setEditorData() function is used by
|
||||
QTableWidget to transfer data from a QTableWidgetItem to the
|
||||
editor. The data is stored as a string; we use
|
||||
QComboBox::findText() to locate it in the combobox.
|
||||
|
||||
Delegates work in terms of models, not items. This makes it
|
||||
possible to use them with any item view class (e.g., QListView,
|
||||
QListWidget, QTreeView, etc.). The transition between model and
|
||||
items is done implicitly by QTableWidget; we don't need to worry
|
||||
about it.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.cpp 3
|
||||
|
||||
The QStyledItemDelegate::setEditorData() function is used by QTableWidget
|
||||
to transfer data back from the editor to the \l{QTableWidgetItem}.
|
||||
|
||||
\snippet widgets/icons/imagedelegate.cpp 4
|
||||
|
||||
The \c emitCommitData() slot simply emit the
|
||||
QAbstractItemDelegate::commitData() signal for the editor that
|
||||
triggered the slot. This signal must be emitted when the editor
|
||||
widget has completed editing the data, and wants to write it back
|
||||
into the model.
|
||||
|
||||
\section2 The Implementation of the Function main()
|
||||
|
||||
\snippet widgets/icons/main.cpp 45
|
||||
|
||||
We use QCommandLineParser to handle any command line options or parameters
|
||||
passed to the application. Then, we resize the main window according
|
||||
to the available screen geometry and show it.
|
||||
*/
|
@ -7,7 +7,6 @@ qt_internal_add_example(calendarwidget)
|
||||
qt_internal_add_example(charactermap)
|
||||
qt_internal_add_example(digitalclock)
|
||||
qt_internal_add_example(groupbox)
|
||||
qt_internal_add_example(icons)
|
||||
qt_internal_add_example(imageviewer)
|
||||
qt_internal_add_example(lineedits)
|
||||
if(QT_FEATURE_movie)
|
||||
|
@ -5,7 +5,6 @@ SUBDIRS = analogclock \
|
||||
charactermap \
|
||||
digitalclock \
|
||||
groupbox \
|
||||
icons \
|
||||
imageviewer \
|
||||
lineedits \
|
||||
movie \
|
||||
|
@ -41,3 +41,23 @@ setRange(minimum, maximum);
|
||||
setMinimum(minimum);
|
||||
setMaximum(maximum);
|
||||
//! [7]
|
||||
|
||||
//! [8]
|
||||
int IconSizeSpinBox::valueFromText(const QString &text) const
|
||||
{
|
||||
static const QRegularExpression regExp(tr("(\\d+)(\\s*[xx]\\s*\\d+)?"));
|
||||
Q_ASSERT(regExp.isValid());
|
||||
|
||||
const QRegularExpressionMatch match = regExp.match(text);
|
||||
if (match.isValid())
|
||||
return match.captured(1).toInt();
|
||||
return 0;
|
||||
}
|
||||
//! [8]
|
||||
|
||||
//! [9]
|
||||
QString IconSizeSpinBox::textFromValue(int value) const
|
||||
{
|
||||
return tr("%1 x %1").arg(value);
|
||||
}
|
||||
//! [9]
|
||||
|
@ -282,8 +282,7 @@ QSizeF QItemDelegatePrivate::doTextLayout(int lineWidth) const
|
||||
the style for drawing.
|
||||
|
||||
\sa {Delegate Classes}, QStyledItemDelegate, QAbstractItemDelegate,
|
||||
{Spin Box Delegate Example}, {Settings Editor Example},
|
||||
{Icons Example}
|
||||
{Spin Box Delegate Example}, {Settings Editor Example}
|
||||
*/
|
||||
|
||||
/*!
|
||||
|
@ -132,12 +132,9 @@ public:
|
||||
for a custom spin box that allows the user to enter icon sizes
|
||||
(e.g., "32 x 32"):
|
||||
|
||||
\snippet widgets/icons/iconsizespinbox.cpp 1
|
||||
\snippet code/src_gui_widgets_qspinbox.cpp 8
|
||||
\codeline
|
||||
\snippet widgets/icons/iconsizespinbox.cpp 2
|
||||
|
||||
See the \l{widgets/icons}{Icons} example for the full source
|
||||
code.
|
||||
\snippet code/src_gui_widgets_qspinbox.cpp 9
|
||||
|
||||
\sa QDoubleSpinBox, QDateTimeEdit, QSlider, {Spin Boxes Example}
|
||||
*/
|
||||
|
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