326 lines
13 KiB
C
326 lines
13 KiB
C
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/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2020 - Raw Material Software Limited
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JUCE is an open source library subject to commercial or open-source
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licensing.
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By using JUCE, you agree to the terms of both the JUCE 6 End-User License
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Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
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End User License Agreement: www.juce.com/juce-6-licence
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Privacy Policy: www.juce.com/juce-privacy-policy
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Or: You may also use this code under the terms of the GPL v3 (see
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www.gnu.org/licenses).
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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class AccessibilityNativeHandle;
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/** Base class for accessible Components.
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This class wraps a Component and provides methods that allow an accessibility client,
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such as VoiceOver on macOS, or Narrator on Windows, to control it.
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It handles hierarchical navigation, properties, state, and various interfaces.
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@tags{Accessibility}
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*/
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class JUCE_API AccessibilityHandler
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{
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public:
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/** Utility struct which holds one or more accessibility interfaces.
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The main purpose of this class is to provide convenience constructors from each
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of the four types of accessibility interface.
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*/
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struct JUCE_API Interfaces
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{
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Interfaces() = default;
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Interfaces (std::unique_ptr<AccessibilityValueInterface> ptr) : value (std::move (ptr)) {}
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Interfaces (std::unique_ptr<AccessibilityTextInterface> ptr) : text (std::move (ptr)) {}
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Interfaces (std::unique_ptr<AccessibilityTableInterface> ptr) : table (std::move (ptr)) {}
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Interfaces (std::unique_ptr<AccessibilityCellInterface> ptr) : cell (std::move (ptr)) {}
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Interfaces (std::unique_ptr<AccessibilityValueInterface> valueIn,
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std::unique_ptr<AccessibilityTextInterface> textIn,
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std::unique_ptr<AccessibilityTableInterface> tableIn,
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std::unique_ptr<AccessibilityCellInterface> cellIn)
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: value (std::move (valueIn)),
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text (std::move (textIn)),
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table (std::move (tableIn)),
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cell (std::move (cellIn))
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{
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}
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std::unique_ptr<AccessibilityValueInterface> value;
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std::unique_ptr<AccessibilityTextInterface> text;
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std::unique_ptr<AccessibilityTableInterface> table;
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std::unique_ptr<AccessibilityCellInterface> cell;
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};
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/** Constructor.
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This will create a AccessibilityHandler which wraps the provided Component and makes
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it visible to accessibility clients. You must also specify a role for the UI element
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from the `AccessibilityRole` list which best describes it.
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To enable users to interact with the UI element you should provide the set of supported
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actions and their associated callbacks via the `accessibilityActions` parameter.
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For UI elements that support more complex interaction the value, text, table, and cell
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interfaces should be implemented as required and passed as the final argument of this
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constructor. See the documentation of these classes for more information about the
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types of control they represent and which methods need to be implemented.
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*/
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AccessibilityHandler (Component& componentToWrap,
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AccessibilityRole accessibilityRole,
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AccessibilityActions actions = {},
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Interfaces interfaces = {});
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/** Destructor. */
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virtual ~AccessibilityHandler();
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//==============================================================================
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/** Returns the Component that this handler represents. */
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const Component& getComponent() const noexcept { return component; }
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/** Returns the Component that this handler represents. */
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Component& getComponent() noexcept { return component; }
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//==============================================================================
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/** The type of UI element that this accessibility handler represents.
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@see AccessibilityRole
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*/
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AccessibilityRole getRole() const noexcept { return role; }
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/** The title of the UI element.
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This will be read out by the system and should be concise, preferably matching
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the visible title of the UI element (if any). For example, this might be the
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text of a button or a simple label.
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The default implementation will call `Component::getTitle()`, but you can override
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this to return a different string if required.
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If neither a name nor a description is provided then the UI element may be
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ignored by accessibility clients.
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This must be a localised string.
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*/
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virtual String getTitle() const { return component.getTitle(); }
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/** A short description of the UI element.
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This may be read out by the system. It should not include the type of the UI
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element and should ideally be a single word, for example "Open" for a button
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that opens a window.
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The default implementation will call `Component::getDescription()`, but you
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can override this to return a different string if required.
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If neither a name nor a description is provided then the UI element may be
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ignored by accessibility clients.
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This must be a localised string.
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*/
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virtual String getDescription() const { return component.getDescription(); }
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/** Some help text for the UI element (if required).
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This may be read out by the system. This string functions in a similar way to
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a tooltip, for example "Click to open window." for a button which opens a window.
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The default implementation will call `Component::getHelpText()`, but you can
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override this to return a different string if required.
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This must be a localised string.
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*/
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virtual String getHelp() const { return component.getHelpText(); }
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/** Returns the current state of the UI element.
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The default implementation of this method will set the focusable flag and, if
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this UI element is currently focused, will also set the focused flag.
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*/
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virtual AccessibleState getCurrentState() const;
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/** Returns true if this UI element should be ignored by accessibility clients. */
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bool isIgnored() const;
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/** Returns true if this UI element is visible within its parent.
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This will always return true for UI elements with the AccessibleState::accessibleOffscreen
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flag set.
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*/
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bool isVisibleWithinParent() const;
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//==============================================================================
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/** Returns the set of actions that the UI element supports and the associated
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callbacks.
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*/
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const AccessibilityActions& getActions() const noexcept;
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/** Returns the value interface for this UI element, or nullptr if it is not supported.
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@see AccessibilityValueInterface
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*/
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AccessibilityValueInterface* getValueInterface() const;
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/** Returns the table interface for this UI element, or nullptr if it is not supported.
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@see AccessibilityTableInterface
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*/
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AccessibilityTableInterface* getTableInterface() const;
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/** Returns the cell interface for this UI element, or nullptr if it is not supported.
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@see AccessibilityCellInterface
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*/
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AccessibilityCellInterface* getCellInterface() const;
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/** Returns the text interface for this UI element, or nullptr if it is not supported.
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@see AccessibilityTextInterface
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*/
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AccessibilityTextInterface* getTextInterface() const;
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//==============================================================================
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/** Returns the first unignored parent of this UI element in the accessibility hierarchy,
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or nullptr if this is a root element without a parent.
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*/
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AccessibilityHandler* getParent() const;
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/** Returns the unignored children of this UI element in the accessibility hierarchy. */
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std::vector<AccessibilityHandler*> getChildren() const;
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/** Checks whether a given UI element is a child of this one in the accessibility
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hierarchy.
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*/
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bool isParentOf (const AccessibilityHandler* possibleChild) const noexcept;
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/** Returns the deepest child of this UI element in the accessibility hierarchy that
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contains the given screen point, or nullptr if there is no child at this point.
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*/
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AccessibilityHandler* getChildAt (Point<int> screenPoint);
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/** Returns the deepest UI element which currently has focus.
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This can be a child of this UI element or, if no child is focused,
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this element itself.
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Note that this can be different to the value of the Component with keyboard
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focus returned by Component::getCurrentlyFocusedComponent().
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@see hasFocus
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*/
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AccessibilityHandler* getChildFocus();
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/** Returns true if this UI element has the focus.
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@param trueIfChildFocused if this is true, this method will also return true
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if any child of this UI element in the accessibility
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hierarchy has focus
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*/
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bool hasFocus (bool trueIfChildFocused) const;
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/** Tries to give focus to this UI element.
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If the UI element is focusable and not ignored this will update the currently focused
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element, try to give keyboard focus to the Component it represents, and notify any
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listening accessibility clients that the current focus has changed.
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@see hasFocus, giveAwayFocus
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*/
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void grabFocus();
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/** If this UI element or any of its children in the accessibility hierarchy currently
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have focus, this will defocus it.
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This will also give away the keyboard focus from the Component it represents, and
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notify any listening accessibility clients that the current focus has changed.
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@see hasFocus, grabFocus
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*/
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void giveAwayFocus() const;
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//==============================================================================
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/** Used to send a notification to any observing accessibility clients that something
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has changed in the UI element.
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@see AccessibilityEvent
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*/
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void notifyAccessibilityEvent (AccessibilityEvent event) const;
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/** A priority level that can help an accessibility client determine how to handle
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an announcement request.
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Exactly what this controls is platform-specific, but generally a low priority
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announcement will be read when the screen reader is free, whereas a high priority
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announcement will interrupt the current speech.
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*/
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enum class AnnouncementPriority
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{
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low,
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medium,
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high
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};
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/** Posts an announcement to be made to the user.
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@param announcementString a localised string containing the announcement to be read out
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@param priority the appropriate priority level for the announcement
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*/
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static void postAnnouncement (const String& announcementString, AnnouncementPriority priority);
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//==============================================================================
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/** @internal */
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AccessibilityNativeHandle* getNativeImplementation() const;
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/** @internal */
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std::type_index getTypeIndex() const { return typeIndex; }
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private:
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//==============================================================================
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friend class AccessibilityNativeHandle;
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//==============================================================================
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void grabFocusInternal (bool);
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void giveAwayFocusInternal() const;
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void takeFocus();
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static AccessibilityHandler* currentlyFocusedHandler;
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//==============================================================================
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Component& component;
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std::type_index typeIndex;
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const AccessibilityRole role;
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AccessibilityActions actions;
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Interfaces interfaces;
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//==============================================================================
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class AccessibilityNativeImpl;
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std::unique_ptr<AccessibilityNativeImpl> nativeImpl;
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static std::unique_ptr<AccessibilityNativeImpl> createNativeImpl (AccessibilityHandler&);
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//==============================================================================
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AccessibilityHandler)
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};
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} // namespace juce
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