chromecast/graphics/gestures/side_swipe_detector.cc - chromium/src.git - Git at Google

 // Copyright 2018 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "chromecast/graphics/gestures/side_swipe_detector.h"

 #include <deque>

 #include "base/auto_reset.h"
 #include "chromecast/base/chromecast_switches.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/events/event.h"
 #include "ui/events/event_rewriter.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/wm/core/coordinate_conversion.h"

 namespace chromecast {
 namespace {
 // The number of pixels from the very left or right of the screen to consider as
 // a valid origin for the left or right swipe gesture.
 constexpr int kDefaultSideGestureStartWidth = 35;

 // The number of pixels from the very top or bottom of the screen to consider as
 // a valid origin for the top or bottom swipe gesture.
 constexpr int kDefaultSideGestureStartHeight = 35;

 // The amount of time after gesture start to allow events which occur in the
 // margin to be stashed and replayed within. For example a tap event which
 // occurs inside the gesture margin will be valid as long as it occurs within
 // the time specified by this threshold.
 constexpr base::TimeDelta kGestureMarginEventsTimeLimit =
     base::Milliseconds(500);

 // Get the correct bottom gesture start height by checking both margin flags in
 // order, and then the default value if neither is set.
 int BottomGestureStartHeight() {
   return GetSwitchValueInt(
       switches::kBottomSystemGestureStartHeight,
       GetSwitchValueInt(switches::kSystemGestureStartHeight,
                         kDefaultSideGestureStartHeight));
 }

 }  // namespace

 SideSwipeDetector::SideSwipeDetector(CastGestureHandler* gesture_handler,
                                      aura::Window* root_window)
     : gesture_start_width_(GetSwitchValueInt(switches::kSystemGestureStartWidth,
                                              kDefaultSideGestureStartWidth)),
       gesture_start_height_(
           GetSwitchValueInt(switches::kSystemGestureStartHeight,
                             kDefaultSideGestureStartHeight)),
       bottom_gesture_start_height_(BottomGestureStartHeight()),
       gesture_handler_(gesture_handler),
       root_window_(root_window),
       current_swipe_(CastSideSwipeOrigin::NONE),
       current_pointer_id_(ui::kPointerIdUnknown) {
   DCHECK(gesture_handler);
   DCHECK(root_window);
   root_window_->GetHost()->GetEventSource()->AddEventRewriter(this);
 }

 SideSwipeDetector::~SideSwipeDetector() {
   root_window_->GetHost()->GetEventSource()->RemoveEventRewriter(this);
 }

 CastSideSwipeOrigin SideSwipeDetector::GetDragPosition(
     const gfx::Point& point,
     const gfx::Rect& screen_bounds) const {
   if (point.y() < (screen_bounds.y() + gesture_start_height_)) {
     return CastSideSwipeOrigin::TOP;
   }
   if (point.x() < (screen_bounds.x() + gesture_start_width_)) {
     return CastSideSwipeOrigin::LEFT;
   }
   if (point.x() >
       (screen_bounds.x() + screen_bounds.width() - gesture_start_width_)) {
     return CastSideSwipeOrigin::RIGHT;
   }
   if (point.y() > (screen_bounds.y() + screen_bounds.height() -
                    bottom_gesture_start_height_)) {
     return CastSideSwipeOrigin::BOTTOM;
   }
   return CastSideSwipeOrigin::NONE;
 }

 void SideSwipeDetector::StashEvent(const ui::TouchEvent& event) {
   // If the time since the gesture start is longer than our threshold, do not
   // stash the event (and clear the stashed events).
   if (current_swipe_time_.Elapsed() > kGestureMarginEventsTimeLimit) {
     stashed_events_.clear();
     return;
   }

   stashed_events_.push_back(event);
 }

 ui::EventDispatchDetails SideSwipeDetector::RewriteEvent(
     const ui::Event& event,
     const Continuation continuation) {
   if (!event.IsTouchEvent()) {
     return SendEvent(continuation, &event);
   }

   const ui::TouchEvent* touch_event = event.AsTouchEvent();

   // Touch events come through in screen pixels, but untransformed. This is the
   // raw coordinate not yet mapped to the root window's coordinate system or the
   // screen. Convert it into the root window's coordinate system, in DIP which
   // is what the rest of this class expects.
   gfx::Point touch_location = touch_event->root_location();
   root_window_->GetHost()->ConvertPixelsToDIP(&touch_location);
   gfx::Rect screen_bounds = display::Screen::GetScreen()
                                 ->GetDisplayNearestPoint(touch_location)
                                 .bounds();
   CastSideSwipeOrigin side_swipe_origin =
       GetDragPosition(touch_location, screen_bounds);

   // A located event has occurred inside the margin. It might be the start of
   // our gesture, or a touch that we need to squash.
   if (current_swipe_ == CastSideSwipeOrigin::NONE &&
       side_swipe_origin != CastSideSwipeOrigin::NONE) {
     // Check to see if we have any potential consumers of events on this side.
     // If not, we can continue on without consuming it.
     if (!gesture_handler_->CanHandleSwipe(side_swipe_origin)) {
       return SendEvent(continuation, &event);
     }

     // Detect the beginning of a system gesture swipe.
     if (touch_event->type() != ui::EventType::kTouchPressed) {
       return SendEvent(continuation, &event);
     }

     current_swipe_ = side_swipe_origin;
     current_pointer_id_ = touch_event->pointer_details().id;

     // Let the subscribers know about the gesture begin.
     gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::BEGIN,
                                       side_swipe_origin, touch_location);

     DVLOG(1) << "side swipe gesture begin @ " << touch_location.ToString();
     current_swipe_time_ = base::ElapsedTimer();

     // Stash a copy of the event should we decide to reconstitute it later if we
     // decide that this isn't in fact a side swipe.
     StashEvent(*touch_event);

     // Avoid corrupt gesture state caused by a missing kGestureScrollEnd event
     // as we potentially transition between web views.
     root_window_->CleanupGestureState();

     // And then stop the original event from propagating.
     return DiscardEvent(continuation);
   }

   // If no swipe in progress, just move on.
   if (current_swipe_ == CastSideSwipeOrigin::NONE) {
     return SendEvent(continuation, &event);
   }

   // If the finger involved is not the one we're looking for, discard it.
   if (touch_event->pointer_details().id != current_pointer_id_) {
     return DiscardEvent(continuation);
   }

   // A swipe is in progress, or has completed, so stop propagation of underlying
   // gesture/touch events, after stashing a copy of the original event.
   StashEvent(*touch_event);

   // The finger has lifted, which means the end of the gesture, or if the finger
   // hasn't travelled far enough, replay the original events.
   if (touch_event->type() == ui::EventType::kTouchReleased) {
     DVLOG(1) << "gesture release; time since press: "
              << current_swipe_time_.Elapsed().InMilliseconds() << "ms @ "
              << touch_location.ToString();
     gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::END, current_swipe_,
                                       touch_location);
     current_swipe_ = CastSideSwipeOrigin::NONE;
     current_pointer_id_ = ui::kPointerIdUnknown;

     // If the finger is still inside the touch margin at release, this is not
     // really a side swipe. Stream out events we stashed for later retrieval.
     if (side_swipe_origin != CastSideSwipeOrigin::NONE &&
         !stashed_events_.empty()) {
       ui::EventDispatchDetails details;
       for (const auto& it : stashed_events_) {
         details = SendEvent(continuation, &it);
         if (details.dispatcher_destroyed)
           break;
       }
       stashed_events_.clear();
       return details;
     }

     // Otherwise, clear them.
     stashed_events_.clear();
     return DiscardEvent(continuation);
   }

   // The system gesture is ongoing...
   gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::CONTINUE,
                                     current_swipe_, touch_location);
   DVLOG(1) << "gesture continue; time since press: "
            << current_swipe_time_.Elapsed().InMilliseconds() << "ms @ "
            << touch_location.ToString();

   return DiscardEvent(continuation);
 }

 }  // namespace chromecast
	// Copyright 2018 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "chromecast/graphics/gestures/side_swipe_detector.h"

	#include <deque>

	#include "base/auto_reset.h"
	#include "chromecast/base/chromecast_switches.h"
	#include "ui/aura/window.h"
	#include "ui/aura/window_event_dispatcher.h"
	#include "ui/aura/window_tree_host.h"
	#include "ui/display/display.h"
	#include "ui/display/screen.h"
	#include "ui/events/event.h"
	#include "ui/events/event_rewriter.h"
	#include "ui/gfx/geometry/point.h"
	#include "ui/gfx/geometry/rect.h"
	#include "ui/wm/core/coordinate_conversion.h"

	namespace chromecast {
	namespace {
	// The number of pixels from the very left or right of the screen to consider as
	// a valid origin for the left or right swipe gesture.
	constexpr int kDefaultSideGestureStartWidth = 35;

	// The number of pixels from the very top or bottom of the screen to consider as
	// a valid origin for the top or bottom swipe gesture.
	constexpr int kDefaultSideGestureStartHeight = 35;

	// The amount of time after gesture start to allow events which occur in the
	// margin to be stashed and replayed within. For example a tap event which
	// occurs inside the gesture margin will be valid as long as it occurs within
	// the time specified by this threshold.
	constexpr base::TimeDelta kGestureMarginEventsTimeLimit =
	base::Milliseconds(500);

	// Get the correct bottom gesture start height by checking both margin flags in
	// order, and then the default value if neither is set.
	int BottomGestureStartHeight() {
	return GetSwitchValueInt(
	switches::kBottomSystemGestureStartHeight,
	GetSwitchValueInt(switches::kSystemGestureStartHeight,
	kDefaultSideGestureStartHeight));
	}

	} // namespace

	SideSwipeDetector::SideSwipeDetector(CastGestureHandler* gesture_handler,
	aura::Window* root_window)
	: gesture_start_width_(GetSwitchValueInt(switches::kSystemGestureStartWidth,
	kDefaultSideGestureStartWidth)),
	gesture_start_height_(
	GetSwitchValueInt(switches::kSystemGestureStartHeight,
	kDefaultSideGestureStartHeight)),
	bottom_gesture_start_height_(BottomGestureStartHeight()),
	gesture_handler_(gesture_handler),
	root_window_(root_window),
	current_swipe_(CastSideSwipeOrigin::NONE),
	current_pointer_id_(ui::kPointerIdUnknown) {
	DCHECK(gesture_handler);
	DCHECK(root_window);
	root_window_->GetHost()->GetEventSource()->AddEventRewriter(this);
	}

	SideSwipeDetector::~SideSwipeDetector() {
	root_window_->GetHost()->GetEventSource()->RemoveEventRewriter(this);
	}

	CastSideSwipeOrigin SideSwipeDetector::GetDragPosition(
	const gfx::Point& point,
	const gfx::Rect& screen_bounds) const {
	if (point.y() < (screen_bounds.y() + gesture_start_height_)) {
	return CastSideSwipeOrigin::TOP;
	}
	if (point.x() < (screen_bounds.x() + gesture_start_width_)) {
	return CastSideSwipeOrigin::LEFT;
	}
	if (point.x() >
	(screen_bounds.x() + screen_bounds.width() - gesture_start_width_)) {
	return CastSideSwipeOrigin::RIGHT;
	}
	if (point.y() > (screen_bounds.y() + screen_bounds.height() -
	bottom_gesture_start_height_)) {
	return CastSideSwipeOrigin::BOTTOM;
	}
	return CastSideSwipeOrigin::NONE;
	}

	void SideSwipeDetector::StashEvent(const ui::TouchEvent& event) {
	// If the time since the gesture start is longer than our threshold, do not
	// stash the event (and clear the stashed events).
	if (current_swipe_time_.Elapsed() > kGestureMarginEventsTimeLimit) {
	stashed_events_.clear();
	return;
	}

	stashed_events_.push_back(event);
	}

	ui::EventDispatchDetails SideSwipeDetector::RewriteEvent(
	const ui::Event& event,
	const Continuation continuation) {
	if (!event.IsTouchEvent()) {
	return SendEvent(continuation, &event);
	}

	const ui::TouchEvent* touch_event = event.AsTouchEvent();

	// Touch events come through in screen pixels, but untransformed. This is the
	// raw coordinate not yet mapped to the root window's coordinate system or the
	// screen. Convert it into the root window's coordinate system, in DIP which
	// is what the rest of this class expects.
	gfx::Point touch_location = touch_event->root_location();
	root_window_->GetHost()->ConvertPixelsToDIP(&touch_location);
	gfx::Rect screen_bounds = display::Screen::GetScreen()
	->GetDisplayNearestPoint(touch_location)
	.bounds();
	CastSideSwipeOrigin side_swipe_origin =
	GetDragPosition(touch_location, screen_bounds);

	// A located event has occurred inside the margin. It might be the start of
	// our gesture, or a touch that we need to squash.
	if (current_swipe_ == CastSideSwipeOrigin::NONE &&
	side_swipe_origin != CastSideSwipeOrigin::NONE) {
	// Check to see if we have any potential consumers of events on this side.
	// If not, we can continue on without consuming it.
	if (!gesture_handler_->CanHandleSwipe(side_swipe_origin)) {
	return SendEvent(continuation, &event);
	}

	// Detect the beginning of a system gesture swipe.
	if (touch_event->type() != ui::EventType::kTouchPressed) {
	return SendEvent(continuation, &event);
	}

	current_swipe_ = side_swipe_origin;
	current_pointer_id_ = touch_event->pointer_details().id;

	// Let the subscribers know about the gesture begin.
	gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::BEGIN,
	side_swipe_origin, touch_location);

	DVLOG(1) << "side swipe gesture begin @ " << touch_location.ToString();
	current_swipe_time_ = base::ElapsedTimer();

	// Stash a copy of the event should we decide to reconstitute it later if we
	// decide that this isn't in fact a side swipe.
	StashEvent(*touch_event);

	// Avoid corrupt gesture state caused by a missing kGestureScrollEnd event
	// as we potentially transition between web views.
	root_window_->CleanupGestureState();

	// And then stop the original event from propagating.
	return DiscardEvent(continuation);
	}

	// If no swipe in progress, just move on.
	if (current_swipe_ == CastSideSwipeOrigin::NONE) {
	return SendEvent(continuation, &event);
	}

	// If the finger involved is not the one we're looking for, discard it.
	if (touch_event->pointer_details().id != current_pointer_id_) {
	return DiscardEvent(continuation);
	}

	// A swipe is in progress, or has completed, so stop propagation of underlying
	// gesture/touch events, after stashing a copy of the original event.
	StashEvent(*touch_event);

	// The finger has lifted, which means the end of the gesture, or if the finger
	// hasn't travelled far enough, replay the original events.
	if (touch_event->type() == ui::EventType::kTouchReleased) {
	DVLOG(1) << "gesture release; time since press: "
	<< current_swipe_time_.Elapsed().InMilliseconds() << "ms @ "
	<< touch_location.ToString();
	gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::END, current_swipe_,
	touch_location);
	current_swipe_ = CastSideSwipeOrigin::NONE;
	current_pointer_id_ = ui::kPointerIdUnknown;

	// If the finger is still inside the touch margin at release, this is not
	// really a side swipe. Stream out events we stashed for later retrieval.
	if (side_swipe_origin != CastSideSwipeOrigin::NONE &&
	!stashed_events_.empty()) {
	ui::EventDispatchDetails details;
	for (const auto& it : stashed_events_) {
	details = SendEvent(continuation, &it);
	if (details.dispatcher_destroyed)
	break;
	}
	stashed_events_.clear();
	return details;
	}

	// Otherwise, clear them.
	stashed_events_.clear();
	return DiscardEvent(continuation);
	}

	// The system gesture is ongoing...
	gesture_handler_->HandleSideSwipe(CastSideSwipeEvent::CONTINUE,
	current_swipe_, touch_location);
	DVLOG(1) << "gesture continue; time since press: "
	<< current_swipe_time_.Elapsed().InMilliseconds() << "ms @ "
	<< touch_location.ToString();

	return DiscardEvent(continuation);
	}

	} // namespace chromecast