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      1 /*
      2  * Copyright (C) 2015 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 static com.android.documentsui.base.DocumentInfo.getCursorString;
     20 
     21 import android.content.Context;
     22 import android.database.Cursor;
     23 import android.provider.DocumentsContract.Document;
     24 import android.support.v7.widget.GridLayoutManager;
     25 import android.support.v7.widget.RecyclerView;
     26 
     27 import com.android.documentsui.ActionHandler;
     28 import com.android.documentsui.Model;
     29 import com.android.documentsui.base.EventListener;
     30 import com.android.documentsui.base.Features;
     31 import com.android.documentsui.base.State;
     32 
     33 import java.util.List;
     34 
     35 /**
     36  * DocumentsAdapter provides glue between a directory Model, and RecylcerView. We've
     37  * abstracted this a bit in order to decompose some specialized support
     38  * for adding dummy layout objects (@see SectionBreakDocumentsAdapter). Handling of the
     39  * dummy layout objects was error prone when interspersed with the core mode / adapter code.
     40  *
     41  * @see ModelBackedDocumentsAdapter
     42  * @see DirectoryAddonsAdapter
     43  */
     44 public abstract class DocumentsAdapter
     45         extends RecyclerView.Adapter<DocumentHolder> {
     46     // Item types used by ModelBackedDocumentsAdapter
     47     public static final int ITEM_TYPE_DOCUMENT = 1;
     48     public static final int ITEM_TYPE_DIRECTORY = 2;
     49     // Item types used by SectionBreakDocumentsAdapterWrapper
     50     public static final int ITEM_TYPE_SECTION_BREAK = Integer.MAX_VALUE;
     51     public static final int ITEM_TYPE_HEADER_MESSAGE = Integer.MAX_VALUE - 1;
     52     public static final int ITEM_TYPE_INFLATED_MESSAGE = Integer.MAX_VALUE - 2;
     53 
     54     // Payloads for notifyItemChange to distinguish between selection and other events.
     55     static final String SELECTION_CHANGED_MARKER = "Selection-Changed";
     56 
     57     /**
     58      * Returns a list of model IDs of items currently in the adapter.
     59      *
     60      * @return A list of Model IDs.
     61      */
     62     public abstract List<String> getModelIds();
     63 
     64     /**
     65      * Triggers item-change notifications by stable ID (as opposed to position).
     66      * Passing an unrecognized ID will result in a warning in logcat, but no other error.
     67      */
     68     public abstract void onItemSelectionChanged(String id);
     69 
     70     /**
     71      * @return The model ID of the item at the given adapter position.
     72      */
     73     public abstract String getModelId(int position);
     74 
     75     abstract EventListener<Model.Update> getModelUpdateListener();
     76 
     77     /**
     78      * Returns a class that yields the span size for a particular element. This is
     79      * primarily useful in {@link DirectoryAddonsAdapter} where
     80      * we adjust sizes.
     81      */
     82     GridLayoutManager.SpanSizeLookup createSpanSizeLookup() {
     83         throw new UnsupportedOperationException();
     84     }
     85 
     86     public boolean hasModelIds() {
     87         return !getModelIds().isEmpty();
     88     }
     89 
     90     static boolean isDirectory(Cursor cursor) {
     91         final String mimeType = getCursorString(cursor, Document.COLUMN_MIME_TYPE);
     92         return Document.MIME_TYPE_DIR.equals(mimeType);
     93     }
     94 
     95     boolean isDirectory(Model model, int position) {
     96         String modelId = getModelIds().get(position);
     97         Cursor cursor = model.getItem(modelId);
     98         return isDirectory(cursor);
     99     }
    100 
    101     /**
    102      * Environmental access for View adapter implementations.
    103      */
    104     interface Environment {
    105         Context getContext();
    106         Features getFeatures();
    107         ActionHandler getActionHandler();
    108         int getColumnCount();
    109         State getDisplayState();
    110         boolean isInSearchMode();
    111         boolean isSelected(String id);
    112         Model getModel();
    113         boolean isDocumentEnabled(String mimeType, int flags);
    114         void initDocumentHolder(DocumentHolder holder);
    115         void onBindDocumentHolder(DocumentHolder holder, Cursor cursor);
    116     }
    117 }
    118