src/com/android/launcher3/statemanager/BaseState.java

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.launcher3.statemanager;

import android.content.Context;

import com.android.launcher3.DeviceProfile;
import com.android.launcher3.views.ActivityContext;

/**
 * Interface representing a state of a StatefulActivity
 */
public interface BaseState<T extends BaseState> {

    // Flag to indicate that Launcher is non-interactive in this state
    int FLAG_NON_INTERACTIVE = 1 << 0;
    int FLAG_DISABLE_RESTORE = 1 << 1;

    static int getFlag(int index) {
        // reserve few spots to base flags
        return 1 << (index + 2);
    }

    /**
     * @return How long the animation to this state should take (or from this state to NORMAL).
     */
    <DEVICE_PROFILE_CONTEXT extends Context & ActivityContext>
    int getTransitionDuration(DEVICE_PROFILE_CONTEXT context, boolean isToState);

    /**
     * Returns the state to go back to from this state
     */
    T getHistoryForState(T previousState);

    /**
     * @return true if the state can be persisted across activity restarts.
     */
    default boolean shouldDisableRestore() {
        return hasFlag(FLAG_DISABLE_RESTORE);
    }

    /**
     * Returns if the state has the provided flag
     */
    boolean hasFlag(int flagMask);

    /**
     * For this state, whether tasks should layout as a grid rather than a list.
     */
    default boolean displayOverviewTasksAsGrid(DeviceProfile deviceProfile) {
        return false;
    }

    /**
     * For this state, whether tasks should show the thumbnail splash.
     */
    default boolean showTaskThumbnailSplash() {
        return false;
    }

    /**
     * For this state, whether member variables and other forms of data state should be preserved
     * or wiped when the state is reapplied. (See {@link StateManager#reapplyState()})
     */
    default boolean shouldPreserveDataStateOnReapply() {
        return false;
    }
}