1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
// 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 <vector>
#include "base/containers/hash_tables.h"
#include "base/memory/weak_ptr.h"
#include "content/common/accessibility_messages.h"
#include "content/public/renderer/render_frame_observer.h"
#include "content/renderer/accessibility/blink_ax_tree_source.h"
#include "third_party/WebKit/public/web/WebAXObject.h"
#include "ui/accessibility/ax_tree_serializer.h"
namespace blink {
class WebDocument;
class WebNode;
};
namespace content {
class RenderFrameImpl;
// The browser process implements 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 belongs to RenderFrameImpl. Accessibility is
// initialized based on the AccessibilityMode of RenderFrameImpl; 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 class implements complete accessibility support for assistive
// technology. It turns on Blink's accessibility code and sends a serialized
// representation of that tree whenever it changes. It also handles requests
// from the browser to perform accessibility actions on nodes in the tree
// (e.g., change focus, or click on a button).
class CONTENT_EXPORT RendererAccessibility : public RenderFrameObserver {
public:
explicit RendererAccessibility(RenderFrameImpl* render_frame);
~RendererAccessibility() override;
// RenderFrameObserver implementation.
bool OnMessageReceived(const IPC::Message& message) override;
// Called when an accessibility notification occurs in Blink.
void HandleWebAccessibilityEvent(const blink::WebAXObject& obj,
blink::WebAXEvent event);
// Called when a new find in page result is highlighted.
void HandleAccessibilityFindInPageResult(
int identifier,
int match_index,
const blink::WebAXObject& start_object,
int start_offset,
const blink::WebAXObject& end_object,
int end_offset);
void FocusedNodeChanged(const blink::WebNode& node);
// This can be called before deleting a RendererAccessibility instance due
// to the accessibility mode changing, as opposed to during frame destruction
// (when there'd be no point).
void DisableAccessibility();
void HandleAXEvent(const blink::WebAXObject& obj, ui::AXEvent event);
protected:
// Returns the main top-level document for this page, or NULL if there's
// no view or frame.
blink::WebDocument GetMainDocument();
// Send queued events from the renderer to the browser.
void SendPendingAccessibilityEvents();
// Check the entire accessibility tree to see if any nodes have
// changed location, by comparing their locations to the cached
// versions. If any have moved, send an IPC with the new locations.
void SendLocationChanges();
// The RenderFrameImpl that owns us.
RenderFrameImpl* render_frame_;
private:
// Handlers for messages from the browser to the renderer.
void OnDoDefaultAction(int acc_obj_id);
void OnEventsAck();
void OnFatalError();
void OnHitTest(gfx::Point point);
void OnSetAccessibilityFocus(int acc_obj_id);
void OnReset(int reset_token);
void OnScrollToMakeVisible(int acc_obj_id, gfx::Rect subfocus);
void OnScrollToPoint(int acc_obj_id, gfx::Point point);
void OnSetFocus(int acc_obj_id);
void OnSetTextSelection(int acc_obj_id, int start_offset, int end_offset);
void OnSetValue(int acc_obj_id, base::string16 value);
// Events from Blink are collected until they are ready to be
// sent to the browser.
std::vector<AccessibilityHostMsg_EventParams> pending_events_;
// The adapter that exposes Blink's accessibility tree to AXTreeSerializer.
BlinkAXTreeSource tree_source_;
// The serializer that sends accessibility messages to the browser process.
ui::AXTreeSerializer<blink::WebAXObject> serializer_;
// Current location of every object, so we can detect when it moves.
base::hash_map<int, gfx::Rect> locations_;
// The most recently observed scroll offset of the root document element.
// TODO(dmazzoni): remove once https://bugs.webkit.org/show_bug.cgi?id=73460
// is fixed.
gfx::Size last_scroll_offset_;
// Set if we are waiting for an accessibility event ack.
bool ack_pending_;
// Nonzero if the browser requested we reset the accessibility state.
// We need to return this token in the next IPC.
int reset_token_;
// So we can queue up tasks to be executed later.
base::WeakPtrFactory<RendererAccessibility> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(RendererAccessibility);
};
} // namespace content
#endif // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_H_
|
