1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_ 6 #define CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_ 7 8 #include "content/common/accessibility_messages.h" 9 #include "content/public/renderer/render_frame_observer.h" 10 #include "third_party/WebKit/public/web/WebAXObject.h" 11 12 namespace blink { 13 class WebDocument; 14 }; 15 16 namespace content { 17 class RenderFrameImpl; 18 19 enum RendererAccessibilityType { 20 // Turns on Blink accessibility and provides a full accessibility 21 // implementation for when assistive technology is running. 22 RendererAccessibilityTypeComplete, 23 24 // Does not turn on Blink accessibility. Only sends a minimal accessible tree 25 // to the browser whenever focus changes. This mode is currently used to 26 // support opening the on-screen keyboard in response to touch events on 27 // Windows 8 in Metro mode. 28 RendererAccessibilityTypeFocusOnly 29 }; 30 31 // The browser process implement native accessibility APIs, allowing 32 // assistive technology (e.g., screen readers, magnifiers) to access and 33 // control the web contents with high-level APIs. These APIs are also used 34 // by automation tools, and Windows 8 uses them to determine when the 35 // on-screen keyboard should be shown. 36 // 37 // An instance of this class (or rather, a subclass) belongs to RenderFrameImpl. 38 // Accessibility is initialized based on the AccessibilityMode of 39 // RenderFrameImpl; it lazily starts as Off or EditableTextOnly depending on 40 // the operating system, and switches to Complete if assistive technology is 41 // detected or a flag is set. 42 // 43 // A tree of accessible objects is built here and sent to the browser process; 44 // the browser process maintains this as a tree of platform-native 45 // accessible objects that can be used to respond to accessibility requests 46 // from other processes. 47 // 48 // This base class just contains common code and will not do anything by itself. 49 // The two subclasses are: 50 // 51 // RendererAccessibilityComplete - turns on Blink accessibility and 52 // provides a full accessibility implementation for when 53 // assistive technology is running. 54 // 55 // RendererAccessibilityFocusOnly - does not turn on Blink 56 // accessibility. Only sends a minimal accessible tree to the 57 // browser whenever focus changes. This mode is currently used 58 // to support opening the on-screen keyboard in response to 59 // touch events on Windows 8 in Metro mode. 60 // 61 class CONTENT_EXPORT RendererAccessibility : public RenderFrameObserver { 62 public: 63 explicit RendererAccessibility(RenderFrameImpl* render_frame); 64 virtual ~RendererAccessibility(); 65 66 // Called when an accessibility notification occurs in Blink. 67 virtual void HandleWebAccessibilityEvent( 68 const blink::WebAXObject& obj, blink::WebAXEvent event) = 0; 69 virtual void FocusedNodeChanged(const blink::WebNode& node) = 0; 70 71 // Gets the type of this RendererAccessibility object. Primarily intended for 72 // testing. 73 virtual RendererAccessibilityType GetType() = 0; 74 75 protected: 76 // Returns the main top-level document for this page, or NULL if there's 77 // no view or frame. 78 blink::WebDocument GetMainDocument(); 79 80 // The RenderFrameImpl that owns us. 81 RenderFrameImpl* render_frame_; 82 83 DISALLOW_COPY_AND_ASSIGN(RendererAccessibility); 84 }; 85 86 } // namespace content 87 88 #endif // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_ 89
