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      1 /*
      2  * Copyright (C) 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.documentsui.dirlist;
     18 
     19 import android.annotation.Nullable;
     20 import android.view.KeyEvent;
     21 import android.view.View;
     22 
     23 /**
     24  * A class that manages focus and keyboard driven navigation in the activity.
     25  */
     26 public interface FocusHandler extends View.OnFocusChangeListener {
     27 
     28     /**
     29      * Handles navigation (setting focus, adjusting selection if needed) arising from incoming key
     30      * events.
     31      *
     32      * @param doc The DocumentHolder receiving the key event.
     33      * @param keyCode
     34      * @param event
     35      * @return Whether the event was handled.
     36      */
     37     boolean handleKey(DocumentHolder doc, int keyCode, KeyEvent event);
     38 
     39     @Override
     40     void onFocusChange(View v, boolean hasFocus);
     41 
     42     void onLayoutCompleted();
     43 
     44     void focusDocument(String modelId);
     45 
     46     /**
     47      * Requests focus on the the directory list. Will specifically
     48      * attempt to focus the item in the directory list that last had focus.
     49      * Scrolls to that item if necessary.
     50      *
     51      * <p>If focus is unsuccessful, return false.
     52      */
     53     boolean focusDirectoryList();
     54 
     55     /**
     56      * Attempts to advance the focus to the next available focus area
     57      * in the app. As of this writing, known focus areas are the sidebar
     58      * and the directory list (specifically an item in the directory list).
     59      */
     60     boolean advanceFocusArea();
     61 
     62     /**
     63      * @return The adapter position of the last focused item.
     64      */
     65     int getFocusPosition();
     66 
     67     /**
     68      * @return True if there is currently an item in focus, false otherwise.
     69      */
     70     boolean hasFocusedItem();
     71 
     72     /**
     73      * If there is an item which has focus, the focus is removed.
     74      */
     75     void clearFocus();
     76 
     77     /**
     78      * @return The modelId of the last focused item. If no item is focused, this should return null.
     79      */
     80     @Nullable String getFocusModelId();
     81 }
     82