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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 <ostream>
#include <string>
#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-forward.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);
// 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_APPLE)
// Fire a platform-specific notification to announce |text|.
virtual void AnnounceText(const base::string16& text) = 0;
// Return this object's delegate.
virtual AXPlatformNodeDelegate* GetDelegate() const = 0;
// Return true if this object is equal to or a descendant of |ancestor|.
virtual bool IsDescendantOf(AXPlatformNode* ancestor) const = 0;
// Set |this| as the primary web contents for the window.
void SetIsPrimaryWebContentsForWindow(bool is_primary);
bool IsPrimaryWebContentsForWindow() const;
// Return the unique ID.
int32_t GetUniqueId() const;
// Creates a string representation of this node's data.
std::string ToString();
// Returns a string representation of the subtree of nodes rooted at this
// node.
std::string SubtreeToString();
friend std::ostream& operator<<(std::ostream& stream, AXPlatformNode& node);
virtual ~AXPlatformNode();
FRIEND_TEST_ALL_PREFIXES(AtkUtilAuraLinuxTest, KeySnooping);
// 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_;
// 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_;
bool is_primary_web_contents_for_window_ = false;
} // namespace ui