overview_gesture_handler.cc revision 0f1bc08d4cfcc34181b0b5cbf065c40f687bf740 
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/shell.h"
8#include "ash/shell_delegate.h"
9#include "ash/wm/overview/window_selector_controller.h"
10#include "ui/events/event.h"
11#include "ui/events/event_constants.h"
12#include "ui/gfx/rect.h"
13#include "ui/gfx/screen.h"
14
15namespace ash {
16namespace internal {
17
18namespace {
19
20// The number of pixels from the top of the screen (a virtual bezel) to allow
21// the overview swipe down gesture to begin within. Note this does not actually
22// prevent handling of the touches so a fullscreen page which consumes these can
23// prevent entering overview with a swipe down.
24const int kTopBezelExtraPixels = 5;
25
26// The threshold before engaging overview on a three finger swipe on the
27// touchpad.
28const float kSwipeThresholdPixels = 300;
29
30}  // namespace;
31
32OverviewGestureHandler::OverviewGestureHandler()
33    : in_top_bezel_gesture_(false),
34      scroll_x_(0),
35      scroll_y_(0) {
36}
37
38OverviewGestureHandler::~OverviewGestureHandler() {
39}
40
41bool OverviewGestureHandler::ProcessScrollEvent(const ui::ScrollEvent& event) {
42  if (event.type() == ui::ET_SCROLL_FLING_START ||
43      event.type() == ui::ET_SCROLL_FLING_CANCEL ||
44      event.finger_count() != 3) {
45    scroll_x_ = scroll_y_ = 0;
46    return false;
47  }
48
49  scroll_x_ += event.x_offset();
50  scroll_y_ += event.y_offset();
51
52  // Horizontal swiping is ignored.
53  if (std::fabs(scroll_x_) >= std::fabs(scroll_y_)) {
54    scroll_x_ = scroll_y_ = 0;
55    return false;
56  }
57
58  // Only allow swipe up to enter overview, down to exit. Ignore extra swiping
59  // in the wrong direction.
60  Shell* shell = Shell::GetInstance();
61  if (shell->window_selector_controller()->IsSelecting()) {
62    if (scroll_y_ < 0)
63      scroll_x_ = scroll_y_ = 0;
64    if (scroll_y_ < kSwipeThresholdPixels)
65      return false;
66  } else {
67    if (scroll_y_ > 0)
68      scroll_x_ = scroll_y_ = 0;
69    if (scroll_y_ > -kSwipeThresholdPixels)
70      return false;
71  }
72
73  // Reset scroll amount on toggling.
74  scroll_x_ = scroll_y_ = 0;
75  shell->delegate()->RecordUserMetricsAction(UMA_TOUCHPAD_GESTURE_OVERVIEW);
76  shell->window_selector_controller()->ToggleOverview();
77  return true;
78}
79
80bool OverviewGestureHandler::ProcessGestureEvent(
81    const ui::GestureEvent& event) {
82  // Detect at the beginning of any gesture whether it begins on the top bezel.
83  if (event.type() == ui::ET_GESTURE_BEGIN &&
84      event.details().touch_points() == 1) {
85    in_top_bezel_gesture_ = !Shell::GetScreen()->GetDisplayNearestPoint(
86        event.location()).bounds().y() + kTopBezelExtraPixels >
87            event.location().y();
88    return false;
89  }
90
91  if (!in_top_bezel_gesture_ ||
92      event.type() != ui::ET_GESTURE_MULTIFINGER_SWIPE ||
93      !event.details().swipe_down() ||
94      event.details().touch_points() != 3) {
95    return false;
96  }
97
98  Shell* shell = Shell::GetInstance();
99  shell->delegate()->RecordUserMetricsAction(UMA_GESTURE_OVERVIEW);
100  shell->window_selector_controller()->ToggleOverview();
101  return true;
102}
103
104}  // namespace internal
105}  // namespace ash
106