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      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(RenderFrameImpl* render_frame);
     41   virtual ~RendererAccessibilityComplete();
     42 
     43   // RenderFrameObserver implementation.
     44   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
     45 
     46   // RendererAccessibility.
     47   virtual void HandleWebAccessibilityEvent(
     48       const blink::WebAXObject& obj, blink::WebAXEvent event) OVERRIDE;
     49   virtual RendererAccessibilityType GetType() OVERRIDE;
     50   virtual void FocusedNodeChanged(const blink::WebNode& node) OVERRIDE;
     51 
     52   void HandleAXEvent(const blink::WebAXObject& obj, ui::AXEvent event);
     53 
     54  protected:
     55   // Send queued events from the renderer to the browser.
     56   void SendPendingAccessibilityEvents();
     57 
     58   // Check the entire accessibility tree to see if any nodes have
     59   // changed location, by comparing their locations to the cached
     60   // versions. If any have moved, send an IPC with the new locations.
     61   void SendLocationChanges();
     62 
     63  private:
     64   // Handlers for messages from the browser to the renderer.
     65   void OnDoDefaultAction(int acc_obj_id);
     66   void OnEventsAck();
     67   void OnChangeScrollPosition(int acc_obj_id, int scroll_x, int scroll_y);
     68   void OnScrollToMakeVisible(int acc_obj_id, gfx::Rect subfocus);
     69   void OnScrollToPoint(int acc_obj_id, gfx::Point point);
     70   void OnSetFocus(int acc_obj_id);
     71   void OnSetTextSelection(int acc_obj_id, int start_offset, int end_offset);
     72   void OnHitTest(gfx::Point point);
     73   void OnReset(int reset_token);
     74   void OnFatalError();
     75 
     76   // Events from Blink are collected until they are ready to be
     77   // sent to the browser.
     78   std::vector<AccessibilityHostMsg_EventParams> pending_events_;
     79 
     80   // The adapter that exposes Blink's accessibility tree to AXTreeSerializer.
     81   BlinkAXTreeSource tree_source_;
     82 
     83   // The serializer that sends accessibility messages to the browser process.
     84   ui::AXTreeSerializer<blink::WebAXObject> serializer_;
     85 
     86   // Current location of every object, so we can detect when it moves.
     87   base::hash_map<int, gfx::Rect> locations_;
     88 
     89   // The most recently observed scroll offset of the root document element.
     90   // TODO(dmazzoni): remove once https://bugs.webkit.org/show_bug.cgi?id=73460
     91   // is fixed.
     92   gfx::Size last_scroll_offset_;
     93 
     94   // Set if we are waiting for an accessibility event ack.
     95   bool ack_pending_;
     96 
     97   // Nonzero if the browser requested we reset the accessibility state.
     98   // We need to return this token in the next IPC.
     99   int reset_token_;
    100 
    101   // So we can queue up tasks to be executed later.
    102   base::WeakPtrFactory<RendererAccessibilityComplete> weak_factory_;
    103 
    104   DISALLOW_COPY_AND_ASSIGN(RendererAccessibilityComplete);
    105 };
    106 
    107 #endif  // CONTENT_RENDERER_ACCESSIBILITY_RENDERER_ACCESSIBILITY_COMPLETE_H_
    108 
    109 }  // namespace content
    110