// Copyright (c) 2012 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.
#ifndef CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_
#define CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_
#include "content/common/accessibility_messages.h"
#include "content/public/renderer/render_view_observer.h"
#include "third_party/WebKit/public/web/WebAXObject.h"
namespace blink {
class WebDocument;
};
namespace content {
class RenderViewImpl;
enum RendererAccessibilityType {
// Turns on Blink accessibility and provides a full accessibility
// implementation for when assistive technology is running.
RendererAccessibilityTypeComplete,
// Does not turn on Blink accessibility. Only sends a minimal accessible tree
// to the browser whenever focus changes. This mode is currently used to
// support opening the on-screen keyboard in response to touch events on
// Windows 8 in Metro mode.
RendererAccessibilityTypeFocusOnly
};
// The browser process implement native accessibility APIs, allowing
// assistive technology (e.g., screen readers, magnifiers) to access and
// control the web contents with high-level APIs. These APIs are also used
// by automation tools, and Windows 8 uses them to determine when the
// on-screen keyboard should be shown.
//
// An instance of this class (or rather, a subclass) belongs to RenderViewImpl.
// Accessibility is initialized based on the AccessibilityMode of
// RenderViewImpl; it lazily starts as Off or EditableTextOnly depending on
// the operating system, and switches to Complete if assistive technology is
// detected or a flag is set.
//
// A tree of accessible objects is built here and sent to the browser process;
// the browser process maintains this as a tree of platform-native
// accessible objects that can be used to respond to accessibility requests
// from other processes.
//
// This base class just contains common code and will not do anything by itself.
// The two subclasses are:
//
// RendererAccessibilityComplete - turns on Blink accessibility and
// provides a full accessibility implementation for when
// assistive technology is running.
//
// RendererAccessibilityFocusOnly - does not turn on Blink
// accessibility. Only sends a minimal accessible tree to the
// browser whenever focus changes. This mode is currently used
// to support opening the on-screen keyboard in response to
// touch events on Windows 8 in Metro mode.
//
class CONTENT_EXPORT RendererAccessibility : public RenderViewObserver {
public:
explicit RendererAccessibility(RenderViewImpl* render_view);
virtual ~RendererAccessibility();
// Called when an accessibility notification occurs in Blink.
virtual void HandleWebAccessibilityEvent(
const blink::WebAXObject& obj, blink::WebAXEvent event) = 0;
// Gets the type of this RendererAccessibility object. Primarily intended for
// testing.
virtual RendererAccessibilityType GetType() = 0;
protected:
// Returns the main top-level document for this page, or NULL if there's
// no view or frame.
blink::WebDocument GetMainDocument();
#ifndef NDEBUG
const std::string AccessibilityEventToString(ui::AXEvent event);
#endif
// The RenderViewImpl that owns us.
RenderViewImpl* render_view_;
// True if verbose logging of accessibility events is on.
bool logging_;
DISALLOW_COPY_AND_ASSIGN(RendererAccessibility);
};
} // namespace content
#endif // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_