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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include "ui/display/display.h"
#include "ui/events/gesture_detection/gesture_detection_export.h"
#include "ui/events/gesture_detection/gesture_detector.h"
#include "ui/events/gesture_detection/gesture_event_data.h"
#include "ui/events/gesture_detection/gesture_touch_uma_histogram.h"
#include "ui/events/gesture_detection/scale_gesture_detector.h"
#include "ui/events/gesture_detection/snap_scroll_controller.h"
namespace ui {
class GESTURE_DETECTION_EXPORT GestureProviderClient {
virtual ~GestureProviderClient() {}
virtual void OnGestureEvent(const GestureEventData& gesture) = 0;
// Supporting double tap events requires adding some extra delay before
// sending single-tap events in order to determine whether its a potential
// double tap or not. This delay may be undesirable in many UI components and
// should be avoided if not needed.
// Returns true if the client wants to receive double tap gesture events.
virtual bool RequiresDoubleTapGestureEvents() const;
// Given a stream of |MotionEvent|'s, provides gesture detection and gesture
// event dispatch.
class GESTURE_DETECTION_EXPORT GestureProvider {
Config(const Config& other);
display::Display display;
GestureDetector::Config gesture_detector_config;
ScaleGestureDetector::Config scale_gesture_detector_config;
// Whether double-tap detection is supported by the platform. If disabled,
// there will be no delay before tap events. Defaults to true.
bool double_tap_support_for_platform_enabled;
// If |gesture_begin_end_types_enabled| is true, fire an ET_GESTURE_BEGIN
// event for every added touch point, and an ET_GESTURE_END event for every
// removed touch point. This requires one ACTION_CANCEL event to be sent per
// touch point, which only occurs on Aura. Defaults to false.
bool gesture_begin_end_types_enabled;
// The min and max size (both length and width, in dips) of the generated
// bounding box for all gesture types. This is useful for touch streams
// that may report zero or unreasonably small or large touch sizes.
// Note that these bounds are only applied for touch or unknown tool types;
// mouse and stylus-derived gestures will not be affected.
// Both values default to 0 (disabled).
float min_gesture_bounds_length;
float max_gesture_bounds_length;
GestureProvider(const Config& config, GestureProviderClient* client);
// Handle the incoming MotionEvent, returning false if the event could not
// be handled.
bool OnTouchEvent(const MotionEvent& event);
// Reset any active gesture detection, including detection of timeout-based
// events (e.g., double-tap or delayed tap) for which the pointer has already
// been released.
void ResetDetection();
// Update whether multi-touch pinch zoom is supported by the platform.
void SetMultiTouchZoomSupportEnabled(bool enabled);
// Update whether double-tap gestures are supported by the platform.
void SetDoubleTapSupportForPlatformEnabled(bool enabled);
// Update whether double-tap gesture detection should be suppressed, e.g.,
// if the page scale is fixed or the page has a mobile viewport. This disables
// the tap delay, allowing rapid and responsive single-tap gestures.
void SetDoubleTapSupportForPageEnabled(bool enabled);
// Whether a scroll gesture is in-progress.
bool IsScrollInProgress() const;
// Whether a pinch gesture is in-progress (i.e. a pinch update has been
// forwarded and detection is still active).
bool IsPinchInProgress() const;
// Whether a double-tap gesture is in-progress (either double-tap or
// double-tap drag zoom).
bool IsDoubleTapInProgress() const;
// May be NULL if there is no currently active touch sequence.
const ui::MotionEvent* current_down_event() const {
return current_down_event_.get();
bool CanHandle(const MotionEvent& event) const;
void OnTouchEventHandlingBegin(const MotionEvent& event);
void OnTouchEventHandlingEnd(const MotionEvent& event);
void UpdateDoubleTapDetectionSupport();
class GestureListenerImpl;
std::unique_ptr<GestureListenerImpl> gesture_listener_;
std::unique_ptr<MotionEvent> current_down_event_;
// Logs information on touch and gesture events.
GestureTouchUMAHistogram uma_histogram_;
// Whether double-tap gesture detection is currently supported.
bool double_tap_support_for_page_;
bool double_tap_support_for_platform_;
const bool gesture_begin_end_types_enabled_;
} // namespace ui