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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/callback.h"
#include "base/lazy_instance.h"
#include "base/observer_list.h"
#include "build/build_config.h"
#include "ui/accessibility/ax_enums.mojom.h"
#include "ui/accessibility/ax_export.h"
#include "ui/accessibility/ax_mode.h"
#include "ui/accessibility/ax_mode_observer.h"
#include "ui/gfx/native_widget_types.h"
namespace ui {
class AXPlatformNodeDelegate;
// AXPlatformNode is the abstract base class for an implementation of
// native accessibility APIs on supported platforms (e.g. Windows, Mac OS X).
// An object that wants to be accessible can derive from AXPlatformNodeDelegate
// and then call AXPlatformNode::Create. The delegate implementation should
// own the AXPlatformNode instance (or otherwise manage its lifecycle).
class AX_EXPORT AXPlatformNode {
using NativeWindowHandlerCallback =
// Create an appropriate platform-specific instance. The delegate owns the
// AXPlatformNode instance (or manages its lifecycle in some other way).
static AXPlatformNode* Create(AXPlatformNodeDelegate* delegate);
// Cast a gfx::NativeViewAccessible to an AXPlatformNode if it is one,
// or return nullptr if it's not an instance of this class.
static AXPlatformNode* FromNativeViewAccessible(
gfx::NativeViewAccessible accessible);
// Return the AXPlatformNode at the root of the tree for a native window.
static AXPlatformNode* FromNativeWindow(gfx::NativeWindow native_window);
// Provide a function that returns the AXPlatformNode at the root of the
// tree for a native window.
static void RegisterNativeWindowHandler(NativeWindowHandlerCallback handler);
// Register and unregister to receive notifications about AXMode changes
// for this node.
static void AddAXModeObserver(AXModeObserver* observer);
static void RemoveAXModeObserver(AXModeObserver* observer);
// Convenience method to get the current accessibility mode.
static AXMode GetAccessibilityMode() { return ax_mode_; }
// Helper static function to notify all global observers about
// the addition of an AXMode flag.
static void NotifyAddAXModeFlags(AXMode mode_flags);
// Must be called by native suggestion code when there are suggestions which
// could be presented in a popup, even if the popup is not presently visible.
// The availability of the popup changes the interactions that will occur
// (down arrow will move the focus into the suggestion popup). An example of a
// suggestion popup is seen in the Autofill feature.
// TODO( Remove this once the autofill state works.
static void OnInputSuggestionsAvailable();
// Must be called when the system goes from a state of having an available
// suggestion popup to none available. If the suggestion popup is still
// available but just hidden, this method should not be called.
// TODO( Remove this once the autofill state works.
static void OnInputSuggestionsUnavailable();
// TODO( Remove this once the autofill state works.
static bool HasInputSuggestions();
// Return the focused object in any UI popup overlaying content, or null.
static gfx::NativeViewAccessible GetPopupFocusOverride();
// Set the focused object withn any UI popup overlaying content, or null.
// The focus override is the perceived focus within the popup, and it changes
// each time a user navigates to a new item within the popup.
static void SetPopupFocusOverride(gfx::NativeViewAccessible focus_override);
// Call Destroy rather than deleting this, because the subclass may
// use reference counting.
virtual void Destroy();
// Get the platform-specific accessible object type for this instance.
// On some platforms this is just a type cast, on others it may be a
// wrapper object or handle.
virtual gfx::NativeViewAccessible GetNativeViewAccessible() = 0;
// Fire a platform-specific notification that an event has occurred on
// this object.
virtual void NotifyAccessibilityEvent(ax::mojom::Event event_type) = 0;
#if defined(OS_MACOSX)
// Fire a platform-specific notification to announce |text|.
virtual void AnnounceText(base::string16& text) = 0;
// Return this object's delegate.
virtual AXPlatformNodeDelegate* GetDelegate() const = 0;
// Return the unique ID
int32_t GetUniqueId() const;
virtual ~AXPlatformNode();
// Global ObserverList for AXMode changes.
static base::LazyInstance<
base::ObserverList<AXModeObserver>::Unchecked>::Leaky ax_mode_observers_;
static base::LazyInstance<NativeWindowHandlerCallback>::Leaky
static AXMode ax_mode_;
static bool has_input_suggestions_;
// This allows UI menu popups like to act as if they are focused in the
// exposed platform accessibility API, even though actual focus remains in
// underlying content.
static gfx::NativeViewAccessible popup_focus_override_;
} // namespace ui