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      1 /*
      2  * Copyright (C) 2017 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 package com.android.documentsui.dirlist;
     17 
     18 import android.view.KeyEvent;
     19 
     20 import com.android.documentsui.base.Events;
     21 import com.android.documentsui.selection.ItemDetailsLookup;
     22 import com.android.documentsui.selection.MotionInputHandler;
     23 import com.android.documentsui.selection.SelectionHelper;
     24 import com.android.documentsui.selection.ItemDetailsLookup.ItemDetails;
     25 import com.android.documentsui.selection.MotionInputHandler.Callbacks;
     26 import com.android.documentsui.selection.SelectionHelper.SelectionPredicate;
     27 
     28 import javax.annotation.Nullable;
     29 
     30 /**
     31  * Class that handles keyboard events on RecyclerView items. The input handler
     32  * must be attached directly to a RecyclerView item since, unlike DOM, events
     33  * don't appear bubble up.
     34  */
     35 public final class KeyInputHandler extends KeyboardEventListener {
     36 
     37     private final SelectionHelper mSelectionHelper;
     38     private final SelectionPredicate mSelectionPredicate;
     39     private final Callbacks mCallbacks;
     40 
     41     public KeyInputHandler(
     42             SelectionHelper selectionHelper,
     43             SelectionPredicate selectionPredicate,
     44             Callbacks callbacks) {
     45 
     46         mSelectionHelper = selectionHelper;
     47         mSelectionPredicate = selectionPredicate;
     48         mCallbacks = callbacks;
     49     }
     50 
     51     @Override
     52     public boolean onKey(@Nullable ItemDetails details, int keyCode, KeyEvent event) {
     53         // Only handle key-down events. This is simpler, consistent with most other UIs, and
     54         // enables the handling of repeated key events from holding down a key.
     55         if (event.getAction() != KeyEvent.ACTION_DOWN) {
     56             return false;
     57         }
     58 
     59         // Ignore tab key events.  Those should be handled by the top-level key handler.
     60         if (keyCode == KeyEvent.KEYCODE_TAB) {
     61             return false;
     62         }
     63 
     64         // Ignore events sent to Addon Holders.
     65         if (details != null) {
     66             int itemType = details.getItemViewType();
     67             if (itemType == DocumentsAdapter.ITEM_TYPE_HEADER_MESSAGE
     68                     || itemType == DocumentsAdapter.ITEM_TYPE_INFLATED_MESSAGE
     69                     || itemType == DocumentsAdapter.ITEM_TYPE_SECTION_BREAK) {
     70                 return false;
     71             }
     72         }
     73 
     74         if (mCallbacks.onFocusItem(details, keyCode, event)) {
     75             // Handle range selection adjustments. Extending the selection will adjust the
     76             // bounds of the in-progress range selection. Each time an unshifted navigation
     77             // event is received, the range selection is restarted.
     78             if (shouldExtendSelection(details, event)) {
     79                 if (!mSelectionHelper.isRangeActive()) {
     80                     // Start a range selection if one isn't active
     81                     mSelectionHelper.startRange(details.getPosition());
     82                 }
     83                 mSelectionHelper.extendRange(details.getPosition());
     84             } else {
     85                 mSelectionHelper.endRange();
     86                 mSelectionHelper.clearSelection();
     87             }
     88             return true;
     89         }
     90 
     91         // we don't yet have a mechanism to handle opening/previewing multiple documents at once
     92         if (mSelectionHelper.getSelection().size() > 1) {
     93             return false;
     94         }
     95 
     96         return mCallbacks.onItemActivated(details, event);
     97     }
     98 
     99     private boolean shouldExtendSelection(ItemDetails item, KeyEvent event) {
    100         if (!Events.isNavigationKeyCode(event.getKeyCode()) || !event.isShiftPressed()) {
    101             return false;
    102         }
    103 
    104         return mSelectionPredicate.canSetStateForId(item.getStableId(), true);
    105     }
    106 
    107     public static abstract class Callbacks extends MotionInputHandler.Callbacks {
    108         public abstract boolean isInteractiveItem(ItemDetails item, KeyEvent e);
    109         public abstract boolean onItemActivated(ItemDetails item, KeyEvent e);
    110         public boolean onFocusItem(ItemDetails details, int keyCode, KeyEvent event) {
    111             return true;
    112         }
    113     }
    114 }