ash/wm/gestures/overview_gesture_handler.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/wm/gestures/overview_gesture_handler.h"
   6
   7 #include "ash/metrics/user_metrics_recorder.h"
   8 #include "ash/shell.h"
   9 #include "ash/wm/overview/window_selector_controller.h"
  10 #include "ui/events/event.h"
  11 #include "ui/events/event_constants.h"
  12
  13 namespace ash {
  14 namespace {
  15
  16 // The threshold before engaging overview on a three finger swipe on the
  17 // touchpad.
  18 const float kSwipeThresholdPixels = 300;
  19
  20 }  // namespace;
  21
  22 OverviewGestureHandler::OverviewGestureHandler() : scroll_x_(0), scroll_y_(0) {}
  23
  24 OverviewGestureHandler::~OverviewGestureHandler() {
  25 }
  26
  27 bool OverviewGestureHandler::ProcessScrollEvent(const ui::ScrollEvent& event) {
  28   if (event.type() == ui::ET_SCROLL_FLING_START ||
  29       event.type() == ui::ET_SCROLL_FLING_CANCEL ||
  30       event.finger_count() != 3) {
  31     scroll_x_ = scroll_y_ = 0;
  32     return false;
  33   }
  34
  35   scroll_x_ += event.x_offset();
  36   scroll_y_ += event.y_offset();
  37
  38   // Horizontal swiping is ignored.
  39   if (std::fabs(scroll_x_) >= std::fabs(scroll_y_)) {
  40     scroll_x_ = scroll_y_ = 0;
  41     return false;
  42   }
  43
  44   // Only allow swipe up to enter overview, down to exit. Ignore extra swiping
  45   // in the wrong direction.
  46   Shell* shell = Shell::GetInstance();
  47   if (shell->window_selector_controller()->IsSelecting()) {
  48     if (scroll_y_ < 0)
  49       scroll_x_ = scroll_y_ = 0;
  50     if (scroll_y_ < kSwipeThresholdPixels)
  51       return false;
  52   } else {
  53     if (scroll_y_ > 0)
  54       scroll_x_ = scroll_y_ = 0;
  55     if (scroll_y_ > -kSwipeThresholdPixels)
  56       return false;
  57   }
  58
  59   // Reset scroll amount on toggling.
  60   scroll_x_ = scroll_y_ = 0;
  61   shell->metrics()->RecordUserMetricsAction(UMA_TOUCHPAD_GESTURE_OVERVIEW);
  62   shell->window_selector_controller()->ToggleOverview();
  63   return true;
  64 }
  65
  66 }  // namespace ash