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taskmenu.qdoc
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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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\class QDesignerTaskMenuExtension
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\brief The QDesignerTaskMenuExtension class allows you to add custom
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menu entries to \QD's task menu.
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\inmodule QtDesigner
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QDesignerTaskMenuExtension provides an interface for creating
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custom task menu extensions. It is typically used to create task
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menu entries that are specific to a plugin in \QD.
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\QD uses the QDesignerTaskMenuExtension to feed its task
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menu. Whenever a task menu is requested, \QD will query
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for the selected widget's task menu extension.
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\image taskmenuextension-example.webp
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A task menu extension is a collection of QActions. The actions
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appear as entries in the task menu when the plugin with the
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specified extension is selected. The image above shows the custom
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\gui {Edit State...} action which appears in addition to \QD's
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default task menu entries: \gui Cut, \gui Copy, \gui Paste etc.
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To create a custom task menu extension, your extension class must
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inherit from both QObject and QDesignerTaskMenuExtension. For
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example:
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\snippet plugins/doc_src_qtdesigner.cpp 9
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Since we are implementing an interface, we must ensure that it
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is made known to the meta-object system using the Q_INTERFACES()
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macro. This enables \QD to use the qobject_cast() function to
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query for supported interfaces using nothing but a QObject
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pointer.
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You must reimplement the taskActions() function to return a list
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of actions that will be included in \QD task menu. Optionally, you
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can reimplement the preferredEditAction() function to set the
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action that is invoked when selecting your plugin and pressing
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\key F2. The preferred edit action must be one of the actions
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returned by taskActions() and, if it's not defined, pressing the
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\key F2 key will simply be ignored.
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In \QD, extensions are not created until they are required. A
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task menu extension, for example, is created when you click the
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right mouse button over a widget in \QD's workspace. For that
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reason you must also construct an extension factory, using either
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QExtensionFactory or a subclass, and register it using \QD's
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\l {QExtensionManager}{extension manager}.
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When a task menu extension is required, \QD's \l
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{QExtensionManager}{extension manager} will run through all its
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registered factories calling QExtensionFactory::createExtension()
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for each until it finds one that is able to create a task menu
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extension for the selected widget. This factory will then make an
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instance of the extension.
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There are four available types of extensions in \QD:
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QDesignerContainerExtension, QDesignerMemberSheetExtension,
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QDesignerPropertySheetExtension, and QDesignerTaskMenuExtension.
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\QD's behavior is the same whether the requested extension is
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associated with a container, a member sheet, a property sheet or a
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task menu.
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The QExtensionFactory class provides a standard extension factory,
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and can also be used as an interface for custom extension
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factories. You can either create a new QExtensionFactory and
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reimplement the QExtensionFactory::createExtension() function. For
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example:
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\snippet plugins/doc_src_qtdesigner.cpp 10
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Or you can use an existing factory, expanding the
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QExtensionFactory::createExtension() function to make the factory
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able to create a task menu extension as well. For example:
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\snippet plugins/doc_src_qtdesigner.cpp 11
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For a complete example using the QDesignerTaskMenuExtension class,
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see the \l {taskmenuextension}{Task Menu Extension
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example}. The example shows how to create a custom widget plugin
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for \QD, and how to use the QDesignerTaskMenuExtension
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class to add custom items to \QD's task menu.
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\sa QExtensionFactory, QExtensionManager, {Creating Custom Widget
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Extensions}
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*/
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/*!
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\fn QDesignerTaskMenuExtension::~QDesignerTaskMenuExtension()
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Destroys the task menu extension.
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*/
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/*!
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\fn QAction *QDesignerTaskMenuExtension::preferredEditAction() const
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Returns the action that is invoked when selecting a plugin with
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the specified extension and pressing \key F2.
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The action must be one of the actions returned by taskActions().
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*/
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/*!
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\fn QList<QAction*> QDesignerTaskMenuExtension::taskActions() const
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Returns the task menu extension as a list of actions which will be
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included in \QD's task menu when a plugin with the specified
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extension is selected.
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The function must be reimplemented to add actions to the list.
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*/
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