content/renderer/accessibility/renderer_accessibility_complete.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_ACCESSIBILITY_RENDERER_ACCESSIBILITY_COMPLETE_H_
   6 #define CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_COMPLETE_H_
   7
   8 #include <set>
   9 #include <vector>
  10
  11 #include "base/containers/hash_tables.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "content/public/renderer/render_view_observer.h"
  14 #include "content/renderer/accessibility/blink_ax_tree_source.h"
  15 #include "content/renderer/accessibility/renderer_accessibility.h"
  16 #include "third_party/WebKit/public/web/WebAXEnums.h"
  17 #include "third_party/WebKit/public/web/WebAXObject.h"
  18 #include "ui/accessibility/ax_node_data.h"
  19 #include "ui/accessibility/ax_tree_serializer.h"
  20
  21 namespace blink {
  22 class WebDocument;
  23 class WebNode;
  24 };
  25
  26 namespace content {
  27 class RenderViewImpl;
  28
  29 // This is the subclass of RendererAccessibility that implements
  30 // complete accessibility support for assistive technology (as opposed to
  31 // partial support - see RendererAccessibilityFocusOnly).
  32 //
  33 // This version turns on Blink's accessibility code and sends
  34 // a serialized representation of that tree whenever it changes. It also
  35 // handles requests from the browser to perform accessibility actions on
  36 // nodes in the tree (e.g., change focus, or click on a button).
  37 class CONTENT_EXPORT RendererAccessibilityComplete
  38     : public RendererAccessibility {
  39  public:
  40   explicit RendererAccessibilityComplete(RenderViewImpl* render_view);
  41   virtual ~RendererAccessibilityComplete();
  42
  43   // RenderView::Observer implementation.
  44   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  45   virtual void FocusedNodeChanged(const blink::WebNode& node) OVERRIDE;
  46   virtual void DidFinishLoad(blink::WebLocalFrame* frame) OVERRIDE;
  47
  48   // RendererAccessibility.
  49   virtual void HandleWebAccessibilityEvent(
  50       const blink::WebAXObject& obj, blink::WebAXEvent event) OVERRIDE;
  51   virtual RendererAccessibilityType GetType() OVERRIDE;
  52
  53   void HandleAXEvent(const blink::WebAXObject& obj, ui::AXEvent event);
  54
  55  protected:
  56   // Send queued events from the renderer to the browser.
  57   void SendPendingAccessibilityEvents();
  58
  59   // Check the entire accessibility tree to see if any nodes have
  60   // changed location, by comparing their locations to the cached
  61   // versions. If any have moved, send an IPC with the new locations.
  62   void SendLocationChanges();
  63
  64  private:
  65   // Handlers for messages from the browser to the renderer.
  66   void OnDoDefaultAction(int acc_obj_id);
  67   void OnEventsAck();
  68   void OnChangeScrollPosition(int acc_obj_id, int scroll_x, int scroll_y);
  69   void OnScrollToMakeVisible(int acc_obj_id, gfx::Rect subfocus);
  70   void OnScrollToPoint(int acc_obj_id, gfx::Point point);
  71   void OnSetFocus(int acc_obj_id);
  72   void OnSetTextSelection(int acc_obj_id, int start_offset, int end_offset);
  73   void OnHitTest(gfx::Point point);
  74   void OnFatalError();
  75
  76   // So we can queue up tasks to be executed later.
  77   base::WeakPtrFactory<RendererAccessibilityComplete> weak_factory_;
  78
  79   // Events from Blink are collected until they are ready to be
  80   // sent to the browser.
  81   std::vector<AccessibilityHostMsg_EventParams> pending_events_;
  82
  83   // The adapter that exposes Blink's accessibility tree to AXTreeSerializer.
  84   BlinkAXTreeSource tree_source_;
  85
  86   // The serializer that sends accessibility messages to the browser process.
  87   ui::AXTreeSerializer<blink::WebAXObject> serializer_;
  88
  89   // Current location of every object, so we can detect when it moves.
  90   base::hash_map<int, gfx::Rect> locations_;
  91
  92   // The most recently observed scroll offset of the root document element.
  93   // TODO(dmazzoni): remove once https://bugs.webkit.org/show_bug.cgi?id=73460
  94   // is fixed.
  95   gfx::Size last_scroll_offset_;
  96
  97   // Set if we are waiting for an accessibility event ack.
  98   bool ack_pending_;
  99
 100   DISALLOW_COPY_AND_ASSIGN(RendererAccessibilityComplete);
 101 };
 102
 103 #endif  // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_COMPLETE_H_
 104
 105 }  // namespace content