ash/keyboard_uma_event_filter.cc

   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 #include "ash/keyboard_uma_event_filter.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "ui/events/event.h"
   9
  10 namespace {
  11
  12 // This threshold is used to drop keystrokes that are more than some time apart.
  13 // These keystrokes are dropped to avoid recording outliers, as well as pauses
  14 // between actual segments of typing.
  15 const int kKeystrokeThresholdInSeconds = 5;
  16
  17 }
  18
  19 namespace ash {
  20
  21 KeyboardUMAEventFilter::KeyboardUMAEventFilter() {}
  22
  23 KeyboardUMAEventFilter::~KeyboardUMAEventFilter() {}
  24
  25 void KeyboardUMAEventFilter::OnKeyEvent(ui::KeyEvent* event) {
  26   // This is a rough approximation, so assume that each key release is the
  27   // result of a typed key.
  28   if (event->type() != ui::ET_KEY_RELEASED)
  29     return;
  30
  31   // Reset the timer on non-character keystrokes.
  32   if (!isprint(event->GetCharacter())) {
  33     last_keystroke_time_ = base::TimeDelta();
  34     return;
  35   }
  36
  37   if (last_keystroke_time_.ToInternalValue() == 0) {
  38     last_keystroke_time_ = event->time_stamp();
  39     return;
  40   }
  41
  42   base::TimeDelta delta = event->time_stamp() - last_keystroke_time_;
  43   if (delta < base::TimeDelta::FromSeconds(kKeystrokeThresholdInSeconds))
  44     UMA_HISTOGRAM_TIMES("Keyboard.KeystrokeDeltas", delta);
  45
  46   last_keystroke_time_ = event->time_stamp();
  47 }
  48
  49 }  // namespace ash