/*这段代码展示了如何在 Android 应用程序中实现一个带有弹出菜单的下拉按钮。
这个 DropdownMenu 类封装了创建一个带有菜单的按钮所需的所有步骤。 */



/*
 * 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.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.PopupMenu;
import android.widget.PopupMenu.OnMenuItemClickListener;

import net.micode.notes.R;

public class DropdownMenu {  /*定义了一个名为 DropdownMenu 的公共类*/
    private Button mButton;
    private PopupMenu mPopupMenu;
    private Menu mMenu;   /*声明了一些私有变量，分别代表按钮、弹出菜单和菜单对象。*/

    public DropdownMenu(Context context, Button button, int menuId) {
        mButton = button;
        mButton.setBackgroundResource(R.drawable.dropdown_icon);  /*构造函数初始化成员变量，设置按钮的背景图片*/
        mPopupMenu = new PopupMenu(context, mButton);
        mMenu = mPopupMenu.getMenu();
        mPopupMenu.getMenuInflater().inflate(menuId, mMenu);/*创建 PopupMenu 实例，获取菜单对象，并通过提供的菜单资源 ID 充气菜单*/
        mButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                mPopupMenu.show();
            }
        });
    }    /*为按钮设置点击监听器，点击时显示弹出菜单*/

    public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
        if (mPopupMenu != null) {
            mPopupMenu.setOnMenuItemClickListener(listener);
        }
    }   /*设置弹出菜单项点击监听器的方法，允许外部设置监听器以便处理菜单项点击事件*/

    public MenuItem findItem(int id) {
        return mMenu.findItem(id);
    }   /*提供一个方法用于根据资源 ID 查找菜单项*/

    public void setTitle(CharSequence title) {
        mButton.setText(title);
    }/*设置按钮文本的方法*/
}
  
  /*这个 DropdownMenu 类使得在应用程序中添加带有弹出菜单的按钮变得更加容易，通过构造函数传入上下文、按钮和菜单资源 ID，就可以轻松地创建和使用带有菜单的按钮。*/