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      1 // Copyright 2013 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_INPUT_INPUT_EVENT_FILTER_H_
      6 #define CONTENT_RENDERER_INPUT_INPUT_EVENT_FILTER_H_
      7 
      8 #include <queue>
      9 #include <set>
     10 
     11 #include "base/callback_forward.h"
     12 #include "base/synchronization/lock.h"
     13 #include "content/common/content_export.h"
     14 #include "content/common/input/input_event_ack_state.h"
     15 #include "content/renderer/input/input_handler_manager_client.h"
     16 #include "ipc/message_filter.h"
     17 #include "third_party/WebKit/public/web/WebInputEvent.h"
     18 
     19 namespace base {
     20 class MessageLoopProxy;
     21 class SingleThreadTaskRunner;
     22 }
     23 
     24 namespace IPC {
     25 class Listener;
     26 class Sender;
     27 }
     28 
     29 // This class can be used to intercept InputMsg_HandleInputEvent messages
     30 // and have them be delivered to a target thread.  Input events are filtered
     31 // based on routing_id (see AddRoute and RemoveRoute).
     32 //
     33 // The user of this class provides an instance of InputEventFilter::Handler,
     34 // which will be passed WebInputEvents on the target thread.
     35 //
     36 
     37 namespace content {
     38 
     39 class CONTENT_EXPORT InputEventFilter : public InputHandlerManagerClient,
     40                                         public IPC::MessageFilter {
     41  public:
     42   InputEventFilter(
     43       IPC::Listener* main_listener,
     44       const scoped_refptr<base::SingleThreadTaskRunner>& main_task_runner,
     45       const scoped_refptr<base::MessageLoopProxy>& target_loop);
     46 
     47   // The |handler| is invoked on the thread associated with |target_loop| to
     48   // handle input events matching the filtered routes.
     49   //
     50   // If INPUT_EVENT_ACK_STATE_NOT_CONSUMED is returned by the handler,
     51   // the original InputMsg_HandleInputEvent message will be delivered to
     52   // |main_listener| on the main thread.  (The "main thread" in this context is
     53   // the thread where the InputEventFilter was constructed.)  The responsibility
     54   // is left to the eventual handler to deliver the corresponding
     55   // InputHostMsg_HandleInputEvent_ACK.
     56   //
     57   virtual void SetBoundHandler(const Handler& handler) OVERRIDE;
     58   virtual void DidAddInputHandler(int routing_id,
     59                                   cc::InputHandler* input_handler) OVERRIDE;
     60   virtual void DidRemoveInputHandler(int routing_id) OVERRIDE;
     61   virtual void DidOverscroll(int routing_id,
     62                              const DidOverscrollParams& params) OVERRIDE;
     63   virtual void DidStopFlinging(int routing_id) OVERRIDE;
     64 
     65   // IPC::MessageFilter methods:
     66   virtual void OnFilterAdded(IPC::Sender* sender) OVERRIDE;
     67   virtual void OnFilterRemoved() OVERRIDE;
     68   virtual void OnChannelClosing() OVERRIDE;
     69   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
     70 
     71  private:
     72   virtual ~InputEventFilter();
     73 
     74   void ForwardToMainListener(const IPC::Message& message);
     75   void ForwardToHandler(const IPC::Message& message);
     76   void SendMessage(scoped_ptr<IPC::Message> message);
     77   void SendMessageOnIOThread(scoped_ptr<IPC::Message> message);
     78 
     79   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
     80   IPC::Listener* main_listener_;
     81 
     82   // The sender_ only gets invoked on the thread corresponding to io_loop_.
     83   scoped_refptr<base::MessageLoopProxy> io_loop_;
     84   IPC::Sender* sender_;
     85 
     86   // The handler_ only gets Run on the thread corresponding to target_loop_.
     87   scoped_refptr<base::MessageLoopProxy> target_loop_;
     88   Handler handler_;
     89 
     90   // Protects access to routes_.
     91   base::Lock routes_lock_;
     92 
     93   // Indicates the routing_ids for which input events should be filtered.
     94   std::set<int> routes_;
     95 
     96   // Specifies whether overscroll notifications are forwarded to the host.
     97   bool overscroll_notifications_enabled_;
     98 
     99   // Used to intercept overscroll notifications while an event is being
    100   // dispatched.  If the event causes overscroll, the overscroll metadata can be
    101   // bundled in the event ack, saving an IPC.  Note that we must continue
    102   // supporting overscroll IPC notifications due to fling animation updates.
    103   scoped_ptr<DidOverscrollParams>* current_overscroll_params_;
    104 };
    105 
    106 }  // namespace content
    107 
    108 #endif  // CONTENT_RENDERER_INPUT_INPUT_EVENT_FILTER_H_
    109