content/renderer/renderer_accessibility.h

   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_RENDERER_ACCESSIBILITY_H_
   6 #define CONTENT_RENDERER_RENDERER_ACCESSIBILITY_H_
   7 #pragma once
   8
   9 #include <vector>
  10
  11 #include "base/hash_tables.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "content/public/renderer/render_view_observer.h"
  14 #include "third_party/WebKit/Source/WebKit/chromium/public/WebAccessibilityNotification.h"
  15
  16 class RenderViewImpl;
  17
  18 namespace WebKit {
  19 class WebAccessibilityObject;
  20 class WebDocument;
  21 class WebNode;
  22 };
  23
  24 namespace webkit_glue {
  25 struct WebAccessibility;
  26 };
  27
  28 // RendererAccessibility belongs to the RenderView. It's responsible for
  29 // sending a serialized representation of WebKit's accessibility tree from
  30 // the renderer to the browser and sending updates whenever it changes, and
  31 // handling requests from the browser to perform accessibility actions on
  32 // nodes in the tree (e.g., change focus, or click on a button).
  33 class RendererAccessibility : public content::RenderViewObserver {
  34  public:
  35   RendererAccessibility(RenderViewImpl* render_view);
  36   virtual ~RendererAccessibility();
  37
  38   // RenderView::Observer implementation.
  39   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  40   virtual void FocusedNodeChanged(const WebKit::WebNode& node) OVERRIDE;
  41   virtual void DidFinishLoad(WebKit::WebFrame* frame) OVERRIDE;
  42
  43   // Called when an accessibility notification occurs in WebKit.
  44   virtual void PostAccessibilityNotification(
  45       const WebKit::WebAccessibilityObject& obj,
  46       WebKit::WebAccessibilityNotification notification);
  47
  48  private:
  49   // One accessibility notification from WebKit. These are queued up and
  50   // used to send tree updates and notification messages from the
  51   // renderer to the browser.
  52   struct Notification {
  53    public:
  54     // The id of the accessibility object.
  55     int32 id;
  56
  57     // The accessibility notification type.
  58     WebKit::WebAccessibilityNotification type;
  59   };
  60
  61   // In order to keep track of what nodes the browser knows about, we keep a
  62   // representation of the browser tree - just IDs and parent/child
  63   // relationships.
  64   struct BrowserTreeNode {
  65     BrowserTreeNode() : id(0) {}
  66     ~BrowserTreeNode() {}
  67     int32 id;
  68     std::vector<BrowserTreeNode*> children;
  69   };
  70
  71   // Send queued notifications from the renderer to the browser.
  72   void SendPendingAccessibilityNotifications();
  73
  74   // Update our representation of what nodes the browser has, given a
  75   // tree of nodes.
  76   void UpdateBrowserTree(const webkit_glue::WebAccessibility& renderer_node);
  77
  78   // Clear the given node and recursively delete all of its descendants
  79   // from the browser tree. (Does not delete |browser_node|).
  80   void ClearBrowserTreeNode(BrowserTreeNode* browser_node);
  81
  82   // Handlers for messages from the browser to the renderer.
  83   void OnDoDefaultAction(int acc_obj_id);
  84   void OnNotificationsAck();
  85   void OnChangeScrollPosition(int acc_obj_id, int scroll_x, int scroll_y);
  86   void OnScrollToMakeVisible(int acc_obj_id, gfx::Rect subfocus);
  87   void OnScrollToPoint(int acc_obj_id, gfx::Point point);
  88   void OnEnable();
  89   void OnSetFocus(int acc_obj_id);
  90
  91   void OnSetTextSelection(int acc_obj_id, int start_offset, int end_offset);
  92
  93   // Whether or not this notification typically needs to send
  94   // updates to its children, too.
  95   bool ShouldIncludeChildren(const Notification& notification);
  96
  97   // Returns the main top-level document for this page, or NULL if there's
  98   // no view or frame.
  99   WebKit::WebDocument GetMainDocument();
 100
 101   // So we can queue up tasks to be executed later.
 102   base::WeakPtrFactory<RendererAccessibility> weak_factory_;
 103
 104   // Notifications from WebKit are collected until they are ready to be
 105   // sent to the browser.
 106   std::vector<Notification> pending_notifications_;
 107
 108   // Our representation of the browser tree.
 109   BrowserTreeNode* browser_root_;
 110
 111   // A map from IDs to nodes in the browser tree.
 112   base::hash_map<int32, BrowserTreeNode*> browser_id_map_;
 113
 114   // The most recently observed scroll offset of the root document element.
 115   // TODO(dmazzoni): remove once https://bugs.webkit.org/show_bug.cgi?id=73460
 116   // is fixed.
 117   gfx::Size last_scroll_offset_;
 118
 119   // Set if we are waiting for an accessibility notification ack.
 120   bool ack_pending_;
 121
 122   // True if verbose logging of accessibility events is on.
 123   bool logging_;
 124
 125   DISALLOW_COPY_AND_ASSIGN(RendererAccessibility);
 126 };
 127
 128 #endif  // CONTENT_RENDERER_RENDERER_ACCESSIBILITY_H_