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java/ui/DropdownMenu.java

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/*
* 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;
/**
* DropdownMenu 类用于创建一个下拉菜单,它将菜单项显示在一个按钮的下拉菜单中。
*/
public class DropdownMenu {
/**
* 关联的按钮,点击它将显示下拉菜单。
*/
private Button mButton;
/**
* 实际的 PopupMenu用于显示菜单项。
*/
private PopupMenu mPopupMenu;
/**
* 菜单项的集合。
*/
private Menu mMenu;
/**
* DropdownMenu 的构造方法,初始化下拉菜单。
* @param context 上下文环境。
* @param button 用于触发下拉菜单显示的按钮。
* @param menuId 菜单项的布局资源 ID。
*/
public DropdownMenu(Context context, Button button, int menuId) {
mButton = button;
setButtonIcon();
mPopupMenu = new PopupMenu(context, mButton);
mMenu = mPopupMenu.getMenu();
inflateMenu(menuId);
setButtonClickListener();
}
/**
* 设置按钮的背景资源为下拉菜单的图标。
*/
private void setButtonIcon() {
mButton.setBackgroundResource(R.drawable.dropdown_icon);
}
/**
* 调用 PopupMenu 的 inflate 方法,根据 menuId 填充菜单项。
* @param menuId 菜单项的布局资源 ID。
*/
private void inflateMenu(int menuId) {
mPopupMenu.getMenuInflater().inflate(menuId, mMenu);
}
/**
* 为按钮设置点击监听器,以显示下拉菜单。
*/
private void setButtonClickListener() {
mButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
mPopupMenu.show();
}
});
}
/**
* 设置下拉菜单项点击监听器。
* @param listener 监听器接口,用于处理菜单项的点击事件。
*/
public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
if (mPopupMenu != null) {
mPopupMenu.setOnMenuItemClickListener(listener);
}
}
/**
* 根据 ID 查找菜单项。
* @param id 菜单项的 ID。
* @return 菜单项的引用,如果不存在则返回 null。
*/
public MenuItem findItem(int id) {
return mMenu.findItem(id);
}
/**
* 设置按钮的标题。
* @param title 标题文本。
*/
public void setTitle(CharSequence title) {
mButton.setText(title);
}
}