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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ash/keyboard/ui/keyboard_ui_model.h"
#include "base/metrics/histogram_functions.h"
namespace keyboard {
namespace {
// Returns whether a given state transition is valid.
// See the design document linked in https://crbug.com/71990.
bool IsAllowedStateTransition(KeyboardUIState from, KeyboardUIState to) {
using State = KeyboardUIState;
switch (GetStateTransitionHash(from, to)) {
// The initial ShowKeyboard scenario
// INITIAL -> LOADING -> HIDDEN -> SHOWN.
case GetStateTransitionHash(State::kInitial, State::kLoading):
case GetStateTransitionHash(State::kLoading, State::kHidden):
case GetStateTransitionHash(State::kHidden, State::kShown):
// Hide scenario
// SHOWN -> WILL_HIDE -> HIDDEN.
case GetStateTransitionHash(State::kShown, State::kWillHide):
case GetStateTransitionHash(State::kWillHide, State::kHidden):
// Focus transition scenario
// SHOWN -> WILL_HIDE -> SHOWN.
case GetStateTransitionHash(State::kWillHide, State::kShown):
// HideKeyboard can be called at anytime (for example on shutdown).
case GetStateTransitionHash(State::kShown, State::kHidden):
// Return to INITIAL when keyboard is disabled.
case GetStateTransitionHash(State::kLoading, State::kInitial):
case GetStateTransitionHash(State::kHidden, State::kInitial):
return true;
default:
return false;
}
}
} // namespace
std::string StateToStr(KeyboardUIState state) {
switch (state) {
case KeyboardUIState::kUnknown:
return "UNKNOWN";
case KeyboardUIState::kInitial:
return "INITIAL";
case KeyboardUIState::kLoading:
return "LOADING";
case KeyboardUIState::kShown:
return "SHOWN";
case KeyboardUIState::kWillHide:
return "WILL_HIDE";
case KeyboardUIState::kHidden:
return "HIDDEN";
}
}
KeyboardUIModel::KeyboardUIModel() = default;
void KeyboardUIModel::ChangeState(KeyboardUIState new_state) {
DCHECK(IsAllowedStateTransition(state_, new_state))
<< "State: " << StateToStr(state_) << " -> " << StateToStr(new_state)
<< " Unexpected transition";
if (new_state == state_)
return;
state_ = new_state;
}
} // namespace keyboard
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