blob: 0bb8e7c90a64fc304080cae573a8a577f2280fe6 [file] [log] [blame]
// 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 "ash/ash_export.h"
#include "base/macros.h"
#include "ui/events/event_handler.h"
namespace ui {
class KeyEvent;
namespace ash {
// This class is used to implement action when a user press and hold the key.
// When a user just pressed and released a key, normal pressed event gets
// generated upon release.
class ASH_EXPORT KeyHoldDetector : public ui::EventHandler {
class Delegate {
virtual ~Delegate() {}
// If this return false, the event handler does not process
// the event at all.
virtual bool ShouldProcessEvent(const ui::KeyEvent* event) const = 0;
// This should return true if the event should start the state transition.
virtual bool IsStartEvent(const ui::KeyEvent* event) const = 0;
// Whether to stop event propagation after processing.
virtual bool ShouldStopEventPropagation() const = 0;
// Called when the key is held.
virtual void OnKeyHold(const ui::KeyEvent* event) = 0;
// Called when the key is release after hold.
virtual void OnKeyUnhold(const ui::KeyEvent* event) = 0;
explicit KeyHoldDetector(std::unique_ptr<Delegate> delegate);
~KeyHoldDetector() override;
// ui::EventHandler overrides:
void OnKeyEvent(ui::KeyEvent* key_event) override;
// A state to keep track of one click and click and hold operation.
// One click:
// INITIAL --(first press)--> PRESSED --(release)--> INITIAL[SEND PRESS]
// Click and hold:
// INITIAL --(first press)--> PRESSED --(press)-->
// HOLD[OnKeyHold] --(press)--> HOLD[OnKeyHold] --(release)-->
// INITIAL[OnKeyUnhold]
enum State { INITIAL, PRESSED, HOLD };
State state_;
std::unique_ptr<Delegate> delegate_;
} // namespace ash