chrome/android/features/start_surface/public/java/src/org/chromium/chrome/features/start_surface/StartSurface.java

// Copyright 2019 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.

package org.chromium.chrome.features.start_surface;

import org.chromium.chrome.browser.tasks.tab_management.GridTabSwitcher;

/** Interface to communicate with the start surface. */
public interface StartSurface {
    /**
     * Defines an interface to pass out tab selecting event.
     */
    interface OnTabSelectingListener extends GridTabSwitcher.OnTabSelectingListener {}

    /**
     * Set the listener to get the {@link Layout#onTabSelecting} event from the Grid Tab Switcher.
     * @param listener The {@link OnTabSelectingListener} to use.
     */
    void setOnTabSelectingListener(OnTabSelectingListener listener);

    /**
     * An observer that is notified when the StartSurface view state changes.
     */
    interface OverviewModeObserver {
        /**
         * Called when overview mode starts showing.
         */
        void startedShowing();

        /**
         * Called when overview mode finishes showing.
         */
        void finishedShowing();

        /**
         * Called when overview mode starts hiding.
         */
        void startedHiding();

        /**
         * Called when overview mode finishes hiding.
         */
        void finishedHiding();
    }

    /**
     * Interface to control the StartSurface.
     */
    interface Controller {
        /**
         * @return Whether or not the overview {@link Layout} is visible.
         */
        boolean overviewVisible();

        /**
         * @param listener Registers {@code listener} for overview mode status changes.
         */
        void addOverviewModeObserver(OverviewModeObserver listener);

        /**
         * @param listener Unregisters {@code listener} for overview mode status changes.
         */
        void removeOverviewModeObserver(OverviewModeObserver listener);

        /**
         * Hide the overview.
         * @param animate Whether we should animate while hiding.
         */
        void hideOverview(boolean animate);

        /**
         * Show the overview.
         * @param animate Whether we should animate while showing.
         */
        void showOverview(boolean animate);

        /**
         * Called by the GridTabSwitcherLayout when the system back button is pressed.
         * @return Whether or not the GridTabSwitcher consumed the event.
         */
        boolean onBackPressed();
    }

    /**
     * @return Controller implementation that can be used for controlling
     *         visibility changes.
     */
    Controller getController();

    /**
     * @return TabGridDelegate implementation that can be used to access the Tab Grid.
     */
    GridTabSwitcher.TabGridDelegate getTabGridDelegate();
}