src/com/android/documentsui/dirlist/DocumentsAdapter.java

/*
 * Copyright (C) 2015 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.documentsui.dirlist;

import static com.android.documentsui.base.DocumentInfo.getCursorString;

import android.content.Context;
import android.database.Cursor;
import android.provider.DocumentsContract.Document;

import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.android.documentsui.ActionHandler;
import com.android.documentsui.Model;
import com.android.documentsui.base.EventListener;
import com.android.documentsui.base.Features;
import com.android.documentsui.base.State;

import java.util.List;

/**
 * DocumentsAdapter provides glue between a directory Model, and RecyclerView. We've
 * abstracted this a bit in order to decompose some specialized support
 * for adding stub layout objects (@see SectionBreakDocumentsAdapter). Handling of the
 * stub layout objects was error prone when interspersed with the core mode / adapter code.
 *
 * @see ModelBackedDocumentsAdapter
 * @see DirectoryAddonsAdapter
 */
public abstract class DocumentsAdapter extends RecyclerView.Adapter<DocumentHolder> {
    // Item types used by ModelBackedDocumentsAdapter
    public static final int ITEM_TYPE_DOCUMENT = 1;
    public static final int ITEM_TYPE_DIRECTORY = 2;
    // Item types used by SectionBreakDocumentsAdapterWrapper
    public static final int ITEM_TYPE_SECTION_BREAK = Integer.MAX_VALUE;
    public static final int ITEM_TYPE_HEADER_MESSAGE = Integer.MAX_VALUE - 1;
    public static final int ITEM_TYPE_INFLATED_MESSAGE = Integer.MAX_VALUE - 2;

    public abstract int getAdapterPosition(String modelId);
    public abstract String getStableId(int adapterPosition);
    public abstract List<String> getStableIds();
    public abstract int getPosition(String id);

    abstract EventListener<Model.Update> getModelUpdateListener();

    /**
     * Returns a class that yields the span size for a particular element. This is
     * primarily useful in {@link DirectoryAddonsAdapter} where
     * we adjust sizes.
     */
    GridLayoutManager.SpanSizeLookup createSpanSizeLookup() {
        throw new UnsupportedOperationException();
    }

    static boolean isDirectory(Cursor cursor) {
        final String mimeType = getCursorString(cursor, Document.COLUMN_MIME_TYPE);
        return Document.MIME_TYPE_DIR.equals(mimeType);
    }

    boolean isDirectory(Model model, int position) {
        String modelId = getStableIds().get(position);
        Cursor cursor = model.getItem(modelId);
        return isDirectory(cursor);
    }

    /**
     * Environmental access for View adapter implementations.
     */
    interface Environment {
        Context getContext();
        Features getFeatures();
        ActionHandler getActionHandler();
        int getColumnCount();
        State getDisplayState();
        boolean isInSearchMode();
        boolean isSelected(String id);
        Model getModel();
        String getCallingAppName();
        boolean isDocumentEnabled(String mimeType, int flags);
        void initDocumentHolder(DocumentHolder holder);
        void onBindDocumentHolder(DocumentHolder holder, Cursor cursor);
    }
}