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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 #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/coordinate_conversion.h"
     10 #include "ash/wm/overview/window_selector_controller.h"
     11 #include "ui/aura/window.h"
     12 #include "ui/events/event.h"
     13 #include "ui/events/event_constants.h"
     14 #include "ui/gfx/rect.h"
     15 #include "ui/gfx/screen.h"
     16 
     17 namespace ash {
     18 namespace {
     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.
     24 const int kTopBezelExtraPixels = 5;
     25 
     26 // The threshold before engaging overview on a three finger swipe on the
     27 // touchpad.
     28 const float kSwipeThresholdPixels = 300;
     29 
     30 }  // namespace;
     31 
     32 OverviewGestureHandler::OverviewGestureHandler()
     33     : in_top_bezel_gesture_(false),
     34       scroll_x_(0),
     35       scroll_y_(0) {
     36 }
     37 
     38 OverviewGestureHandler::~OverviewGestureHandler() {
     39 }
     40 
     41 bool 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->metrics()->RecordUserMetricsAction(UMA_TOUCHPAD_GESTURE_OVERVIEW);
     76   shell->window_selector_controller()->ToggleOverview();
     77   return true;
     78 }
     79 
     80 bool 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     gfx::Point point_in_screen(event.location());
     86     aura::Window* target = static_cast<aura::Window*>(event.target());
     87     wm::ConvertPointToScreen(target, &point_in_screen);
     88     in_top_bezel_gesture_ = !Shell::GetScreen()->GetDisplayNearestPoint(
     89         point_in_screen).bounds().y() + kTopBezelExtraPixels >
     90             point_in_screen.y();
     91     return false;
     92   }
     93 
     94   if (!in_top_bezel_gesture_ ||
     95       event.type() != ui::ET_GESTURE_SWIPE ||
     96       !event.details().swipe_down() ||
     97       event.details().touch_points() != 3) {
     98     return false;
     99   }
    100 
    101   Shell* shell = Shell::GetInstance();
    102   shell->metrics()->RecordUserMetricsAction(UMA_GESTURE_OVERVIEW);
    103   shell->window_selector_controller()->ToggleOverview();
    104   return true;
    105 }
    106 
    107 }  // namespace ash
    108