content/browser/renderer_host/input/tap_suppression_controller.h

   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_BROWSER_RENDERER_HOST_INPUT_TAP_SUPPRESSION_CONTROLLER_H_
   6 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_TAP_SUPPRESSION_CONTROLLER_H_
   7
   8 #include "base/time/time.h"
   9 #include "base/timer/timer.h"
  10 #include "content/common/content_export.h"
  11
  12 namespace content {
  13
  14 class TapSuppressionControllerClient;
  15
  16 // The core controller for suppression of taps (touchpad or touchscreen)
  17 // immediately following a GestureFlingCancel event (caused by the same tap).
  18 // Only taps of sufficient speed and within a specified time window after a
  19 // GestureFlingCancel are suppressed.
  20 class CONTENT_EXPORT TapSuppressionController {
  21  public:
  22   struct CONTENT_EXPORT Config {
  23     Config();
  24
  25     // Defaults to false, in which case no suppression is performed.
  26     bool enabled;
  27
  28     // The maximum time allowed between a GestureFlingCancel and its
  29     // corresponding tap down.
  30     base::TimeDelta max_cancel_to_down_time;
  31
  32     // The maximum time allowed between a single tap's down and up events.
  33     base::TimeDelta max_tap_gap_time;
  34   };
  35
  36   TapSuppressionController(TapSuppressionControllerClient* client,
  37                            const Config& config);
  38   virtual ~TapSuppressionController();
  39
  40   // Should be called whenever a GestureFlingCancel event is received.
  41   void GestureFlingCancel();
  42
  43   // Should be called whenever an ACK for a GestureFlingCancel event is
  44   // received. |processed| is true when the GestureFlingCancel actually stopped
  45   // a fling and therefore should suppress the forwarding of the following tap.
  46   void GestureFlingCancelAck(bool processed);
  47
  48   // Should be called whenever a tap down (touchpad or touchscreen) is received.
  49   // Returns true if the tap down should be deferred. The caller is responsible
  50   // for keeping the event for later release, if needed.
  51   bool ShouldDeferTapDown();
  52
  53   // Should be called whenever a tap ending event is received. Returns true if
  54   // the tap event should be suppressed.
  55   bool ShouldSuppressTapEnd();
  56
  57  protected:
  58   virtual base::TimeTicks Now();
  59   virtual void StartTapDownTimer(const base::TimeDelta& delay);
  60   virtual void StopTapDownTimer();
  61   void TapDownTimerExpired();
  62
  63  private:
  64   friend class MockTapSuppressionController;
  65
  66   enum State {
  67     DISABLED,
  68     NOTHING,
  69     GFC_IN_PROGRESS,
  70     TAP_DOWN_STASHED,
  71     LAST_CANCEL_STOPPED_FLING,
  72   };
  73
  74   TapSuppressionControllerClient* client_;
  75   base::OneShotTimer<TapSuppressionController> tap_down_timer_;
  76   State state_;
  77
  78   base::TimeDelta max_cancel_to_down_time_;
  79   base::TimeDelta max_tap_gap_time_;
  80
  81   // TODO(rjkroege): During debugging, the event times did not prove reliable.
  82   // Replace the use of base::TimeTicks with an accurate event time when they
  83   // become available post http://crbug.com/119556.
  84   base::TimeTicks fling_cancel_time_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(TapSuppressionController);
  87 };
  88
  89 }  // namespace content
  90
  91 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_TAP_SUPPRESSION_CONTROLLER_H_