Notes/src/ui/NotesListAdapter.java

/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * 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 net.micode.notes.ui;

import android.content.Context;
import android.database.Cursor;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;

import net.micode.notes.data.Notes;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;


public class NotesListAdapter extends CursorAdapter {//Adapter作为Activity和ListView之间的适配器，将Cursor数据转换为ListView可以理解的视图格式
    private static final String TAG = "NotesListAdapter"; // 日志标签
    private Context mContext; // 上下文对象
    private HashMap<Integer, Boolean> mSelectedIndex; // 选中项索引映射
    private int mNotesCount; // 笔记数量（排除文件夹）
    private boolean mChoiceMode; // 是否处于选择模式

    public static class AppWidgetAttribute { // 小部件属性类，用于存储小部件的ID和类型
        public int widgetId; // 小部件ID
        public int widgetType; // 小部件类型
    };

    public NotesListAdapter(Context context) { // 构造函数，创建NotesListAdapter实例
        super(context, null);
        mSelectedIndex = new HashMap<Integer, Boolean>(); // 初始化选中项映射
        mContext = context;
        mNotesCount = 0;
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return new NotesListItem(context); // 创建新的NotesListItem
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        if (view instanceof NotesListItem) {
            NoteItemData itemData = new NoteItemData(context, cursor); // 创建数据模型
            ((NotesListItem) view).bind(context, itemData, mChoiceMode, // 绑定数据到视图
                    isSelectedItem(cursor.getPosition()));
        }
    }

    public void setCheckedItem(final int position, final boolean checked) {
        mSelectedIndex.put(position, checked); // 更新选中状态
        notifyDataSetChanged(); // 通知数据变化，刷新UI
    }

    public boolean isInChoiceMode() {
        return mChoiceMode; // 检查是否处于选择模式
    }

    public void setChoiceMode(boolean mode) {
        mSelectedIndex.clear(); // 清除之前的选中状态
        mChoiceMode = mode; // 更新模式标志
    }

    public void selectAll(boolean checked) {
        Cursor cursor = getCursor();
        for (int i = 0; i < getCount(); i++) {
            if (cursor.moveToPosition(i)) {
                if (NoteItemData.getNoteType(cursor) == Notes.TYPE_NOTE) { // 只处理普通笔记，跳过文件夹
                    setCheckedItem(i, checked); // 设置选中状态
                }
            }
        }
    }

    public HashSet<Long> getSelectedItemIds() {// 获取选中项的ID集合
        HashSet<Long> itemSet = new HashSet<Long>();
        for (Integer position : mSelectedIndex.keySet()) {
            if (mSelectedIndex.get(position) == true) {
                Long id = getItemId(position); // 获取选中项的ID
                if (id == Notes.ID_ROOT_FOLDER) {
                    Log.d(TAG, "Wrong item id, should not happen");
                } else {
                    itemSet.add(id); // 添加到集合
                }
            }
        }
        return itemSet;
    }

    public HashSet<AppWidgetAttribute> getSelectedWidget() {// 获取选中项的小部件属性集合
        HashSet<AppWidgetAttribute> itemSet = new HashSet<AppWidgetAttribute>();
        for (Integer position : mSelectedIndex.keySet()) {
            if (mSelectedIndex.get(position) == true) {
                Cursor c = (Cursor) getItem(position);
                if (c != null) {
                    AppWidgetAttribute widget = new AppWidgetAttribute();
                    NoteItemData item = new NoteItemData(mContext, c);
                    widget.widgetId = item.getWidgetId(); // 获取小部件ID
                    widget.widgetType = item.getWidgetType(); // 获取小部件类型
                    itemSet.add(widget);
                    // Don't close cursor here, only the adapter could close it
                } else {
                    Log.e(TAG, "Invalid cursor");
                    return null;
                }
            }
        }
        return itemSet;
    }

    public int getSelectedCount() {// 获取选中项数量
        Collection<Boolean> values = mSelectedIndex.values();
        if (null == values) {
            return 0;
        }
        Iterator<Boolean> iter = values.iterator();
        int count = 0;
        while (iter.hasNext()) {
            if (true == iter.next()) {
                count++;
            }
        }
        return count; // 返回选中项数量
    }

    public boolean isAllSelected() {// 检查是否所有笔记都被选中
        int checkedCount = getSelectedCount();
        return (checkedCount != 0 && checkedCount == mNotesCount); 
    }

    public boolean isSelectedItem(final int position) {// 检查指定位置的项是否被选中
        if (null == mSelectedIndex.get(position)) {
            return false;
        }
        return mSelectedIndex.get(position); // 检查指定位置的项是否被选中
    }

    @Override
    protected void onContentChanged() {
        super.onContentChanged();
        calcNotesCount(); // 当内容变化时，重新计算笔记数量
    }

    @Override
    public void changeCursor(Cursor cursor) {
        super.changeCursor(cursor);
        calcNotesCount(); // 当游标变化时，重新计算笔记数量
    }

    private void calcNotesCount() {// 计算普通笔记的数量
        mNotesCount = 0;
        for (int i = 0; i < getCount(); i++) {
            Cursor c = (Cursor) getItem(i);
            if (c != null) {
                if (NoteItemData.getNoteType(c) == Notes.TYPE_NOTE) { // 只统计普通笔记，排除文件夹
                    mNotesCount++;
                }
            } else {
                Log.e(TAG, "Invalid cursor");
                return;
            }
        }
    }
}