Unity UGUI 基础之 DropDown（下拉列表框）的简单使用（简单改变样式/动态下来列表的数据添加删除/列表事件监听等）

比眉伴天荒 2022-12-05 15:27 154阅读 0赞

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70][]

# Unity UGUI 基础 之 DropDown（下拉列表框） 的简单使用（简单改变样式/动态下来列表的数据添加删除/列表事件监听等） #

**目录**

Unity UGUI 基础 之 DropDown（下拉列表框） 的简单使用（简单改变样式/动态下来列表的数据添加删除/列表事件监听等）

一、简单介绍

二、DropDown  在 Unity 的样子中大概如下图（Item 背景样式简单修改）

三、DropDown 组件，及组件上的属性说明

四、DropDown 组件下某些子组件简单说明

五、注意事项

六、简单案例

七、关键代码

八、DropDown 源码

--------------------

## 一、简单介绍 ##

UGUI，是Unity自带的 GUI 系统，有别于 NGUI；使用 UGUI 也能制作出比较酷炫的效果 。

本节介绍，使用 UGUI DropDown 下拉列表的一些简单的使用说明，和使用方法，方法不唯一，欢迎指正。

> **DropDown**：控件显示当前选择的选项。一旦单击，它将打开选项列表，以便可以选择一个新选项。选择新选项后，关闭的列表再次关闭，控件将显示新选定的选项。如果用户单击控件本身或画布中的任何其他位置，列表也将关闭。

## 二、DropDown  在 Unity 的样子中大概如下图（Item 背景样式简单修改） ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 1][]

## 三、DropDown 组件，及组件上的属性说明 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 2][]

<table> 
 <tbody> 
 <tr> 
 <td> Interactable </td> 
 <td> 可交互 </td> 
 <td> 是否可点击 </td> 
 </tr> 
 <tr> 
 <td> Transition </td> 
 <td> 过渡 </td> 
 <td> 
 <ul> 
 <li> None：无 </li> 
 <li> Color Tint：颜色色彩 
 <ul> 
 <li> Target Graphic：目标图形 </li> 
 <li> Normal Color：正常颜色 </li> 
 <li> Highlighted Color：高亮颜色 </li> 
 <li> Pressed Color：按下颜色 </li> 
 <li> Selected Color：选择颜色 </li> 
 <li> Disabled Color：已禁用颜色 </li> 
 <li> Color Multiplier：色彩乘数 </li> 
 <li> Fade Duration：淡化持续时间 </li> 
 </ul></li> 
 <li> Sprite Swap：精灵交换 
 <ul> 
 <li> Target Graphic：目标图形 </li> 
 <li> Highlighted Sprite：高亮精灵 </li> 
 <li> Pressed&nbsp;Sprite：按下精灵 </li> 
 <li> Selected Sprite：选择精灵 </li> 
 <li> Disabled Sprite：已禁用精灵 </li> 
 </ul></li> 
 <li> Animation：动画 
 <ul> 
 <li> Normal Trigger：正常触发 </li> 
 <li> Highlighted&nbsp;Trigger：高亮触发 </li> 
 <li> Pressed&nbsp;Trigger：按下触发 </li> 
 <li> Selected Trigger：选择触发 </li> 
 <li> Disabled Trigger：引禁用触发 </li> 
 <li> Auto Generate Animation&nbsp;自动生成动画 </li> 
 </ul></li> 
 </ul></td> 
 </tr> 
 <tr> 
 <td> Navigation </td> 
 <td> 导航 </td> 
 <td> 
 <ul> 
 <li> None：无 </li> 
 <li> Horizontal：水平 </li> 
 <li> Vertical：垂直 </li> 
 <li> Automatic：自动 </li> 
 <li> Explicit：显式 
 <ul> 
 <li> Select On Up：向上选择 </li> 
 <li> Select On Down：向下选择 </li> 
 <li> Select On Left：向左选择 </li> 
 <li> Select On Right：向右选择 </li> 
 </ul></li> 
 <li> Visualize：可视化，把按键能够导航到的路径可视化，高亮的黄色箭头为当前按钮可导航到的目标 </li> 
 </ul></td> 
 </tr> 
 <tr> 
 <td> Template </td> 
 <td> 模板 </td> 
 <td> 下拉使用的模板样式 </td> 
 </tr> 
 <tr> 
 <td> Caption Text </td> 
 <td> 标题文本 </td> 
 <td> 当前选择的显示文本 </td> 
 </tr> 
 <tr> 
 <td> Caption Image </td> 
 <td> 标题图像 </td> 
 <td> 当前选择的显示图片 </td> 
 </tr> 
 <tr> 
 <td> Item Text </td> 
 <td> 项文本 </td> 
 <td> 下拉框选项模板里的文字，不填会导致选项列表中的每个选项不会修改模板里的文字 </td> 
 </tr> 
 <tr> 
 <td> Item Image </td> 
 <td> 项图像 </td> 
 <td> 下拉框选项模板里的图片，不填会导致选项列表中的每个选项不会修改模板里的图片 </td> 
 </tr> 
 <tr> 
 <td> Value </td> 
 <td> 值 </td> 
 <td> 当前选择的值（0开始） </td> 
 </tr> 
 <tr> 
 <td> Options </td> 
 <td> 选项 </td> 
 <td> 可选择项 </td> 
 </tr> 
 <tr> 
 <td> On Value Changed（Int32） </td> 
 <td> 值改变时（32位整数） </td> 
 <td> 值调整时触发的事件 </td> 
 </tr> 
 </tbody> 
</table>

## 四、DropDown 组件下某些子组件简单说明 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 3][]

Dropdown：图片，带Dropdown组件，作为选中框的底图

Label：文本，作为标题文本，当前显示的文本

Arrow：图片，作为下拉按钮

Template：生成下拉列表的模板，可以在这里修改下拉列表的显示样式

Item Background：图片，这里可修改下拉列表Item的背景设置

Item Checkmark：图片，这里可修改下拉列表Item的前面的 勾，根据需要修改

Item Label：文本，这里可修改下拉列表Item的的文本，根据需要修改

Scrollbar：滑动条

## 五、注意事项 ##

1、DropDown 通过代码设置选择的下拉选项（即是属性 vuale，而不是鼠标点击设置）的时候，也会触发 OnValueChanged 事件，跟UGUI的 Toggle 等不一样，这里需要自己处理，看情况需不需要（后面介绍处理方法，见后面代码）

## 六、简单案例 ##

使用代码，实现DropDown 的下拉列表的清空，添加等简单功能

1、效果预览

![20200911152920674.gif][]

2、场景布置如此

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 4][]

3、其中 Item Background 背景图片修改默认图片

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 5][]

4、在工程中，新建脚本，编写代码，控制 DropDown 的某些功能显示

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 6][]

5、把脚本挂载到场景中，并对应赋值

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 7][]

6、运行场景，效果如上

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQzNjEyODA_size_16_color_FFFFFF_t_70 8][]

## 七、关键代码 ##

1、DropDownTest

using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Events;
 using UnityEngine.UI;
 
 public class DropDownTest : MonoBehaviour
 {
 
 public Dropdown dropDown;
 
 // 是否是代码设置下拉 Item 值
 private bool isCodeSetItemValue = false;
 
 void Start()
 {
 // 设置监听
 SetDropDownAddListener(OnValueChange);
 SetDropDownItemValue(1);
 }
 
 /// <summary>
 /// 当点击后值改变是触发 (切换下拉选项)
 /// </summary>
 /// <param name="v">是点击的选项在OptionData下的索引值</param>
 void OnValueChange(int v)
 {
 //切换选项 时处理其他的逻辑...
 Debug.Log("点击下拉控件的索引是..." + v);
 }
 
 private void Update()
 {
 if (Input.GetKeyDown(KeyCode.Space)) {
 
 List<Dropdown.OptionData> listOptions = new List<Dropdown.OptionData>();
 listOptions.Add(new Dropdown.OptionData("Option 0"));
 listOptions.Add(new Dropdown.OptionData("Option 1"));
 
 AddDropDownOptionsData(listOptions);
 }
 
 if (Input.GetKeyDown(KeyCode.A))
 {
 
 AddDropDownOptionsData("Option " + dropDown.options.Count);
 }
 
 if (Input.GetKeyDown(KeyCode.R))
 {
 RemoveAtDropDownOptionsData(dropDown.options.Count - 1);
 }
 
 if (Input.GetKeyDown(KeyCode.C))
 {
 ClearDropDownOptionsData();
 }
 }
 
 /// <summary>
 /// 设置选择的下拉Item
 /// </summary>
 /// <param name="ItemIndex"></param>
 void SetDropDownItemValue(int ItemIndex)
 {
 // 代码设置的值
 isCodeSetItemValue = true;
 
 if (dropDown.options == null) {
 
 Debug.Log(GetType()+ "/SetDropDownItemValue()/下拉列表为空，请检查");
 return;
 }
 if (ItemIndex >= dropDown.options.Count) {
 ItemIndex = dropDown.options.Count - 1;
 }
 
 if (ItemIndex < 0 )
 {
 ItemIndex = 0;
 }
 
 dropDown.value = ItemIndex;
 }
 
 
 /// <summary>
 /// 是否可以点击
 /// </summary>
 void SetDropDownInteractable() {
 //是否可以点击
 dropDown.interactable = true;
 }
 
 /// <summary>
 /// 设置显示字体大小
 /// </summary>
 /// <param name="fontSize"></param>
 void SetDropDownCaptionTextFontSize(int fontSize) {
 //设置显示字体大小
 dropDown.captionText.fontSize = fontSize;
 }
 
 /// <summary>
 /// 设置下拉Item显示字体大小
 /// </summary>
 /// <param name="fontSize"></param>
 void SetDropDownItemTextFontSize(int fontSize)
 {
 //设置下拉Item显示字体大小
 dropDown.itemText.fontSize = fontSize;
 }
 
 /// <summary>
 /// 添加一个列表下拉数据
 /// </summary>
 /// <param name="listOptions"></param>
 void AddDropDownOptionsData(List<Dropdown.OptionData> listOptions) {
 dropDown.AddOptions(listOptions);
 }
 
 /// <summary>
 /// 添加一个下拉数据
 /// </summary>
 /// <param name="itemText"></param>
 void AddDropDownOptionsData(string itemText) {
 //添加一个下拉选项
 Dropdown.OptionData data = new Dropdown.OptionData();
 data.text = itemText;
 //data.image = "指定一个图片做背景不指定则使用默认"；
 dropDown.options.Add(data);
 }
 
 
 /// <summary>
 /// 移除指定位置 参数:索引
 /// </summary>
 /// <param name="index"></param>
 void RemoveAtDropDownOptionsData(int index) {
 
 // 安全校验
 if (index >= dropDown.options.Count || index < 0) {
 return;
 }
 
 //移除指定位置 参数:索引
 dropDown.options.RemoveAt(index);
 }
 
 
 /// <summary>
 /// 直接清理掉所有的下拉选项
 /// </summary>
 void ClearDropDownOptionsData() {
 //直接清理掉所有的下拉选项，
 dropDown.ClearOptions();
 }
 
 /// <summary>
 /// 当点击后值改变是触发 (切换下拉选项)
 /// </summary>
 void SetDropDownAddListener(UnityAction<int> OnValueChangeListener)
 {
 
 
 //当点击后值改变是触发 (切换下拉选项)
 dropDown.onValueChanged.AddListener((value)=> {
 // 手动代码设置的值不触发事件（根据需要可以保留或者去掉）
 if (isCodeSetItemValue == true)
 {
 
 isCodeSetItemValue = false;
 
 return;
 }
 
 OnValueChangeListener(value);
 });
 }
 
 
 
 }

## 八、DropDown 源码 ##

using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.Events;
 using UnityEngine.EventSystems;
 using UnityEngine.UI.CoroutineTween;
 
 namespace UnityEngine.UI
 {
 [AddComponentMenu("UI/Dropdown", 35)]
 [RequireComponent(typeof(RectTransform))]
 /// <summary>
 /// A standard dropdown that presents a list of options when clicked, of which one can be chosen.
 /// </summary>
 /// <remarks>
 /// The dropdown component is a Selectable. When an option is chosen, the label and/or image of the control changes to show the chosen option.
 ///
 /// When a dropdown event occurs a callback is sent to any registered listeners of onValueChanged.
 /// </remarks>
 public class Dropdown : Selectable, IPointerClickHandler, ISubmitHandler, ICancelHandler
 {
 protected internal class DropdownItem : MonoBehaviour, IPointerEnterHandler, ICancelHandler
 {
 [SerializeField]
 private Text m_Text;
 [SerializeField]
 private Image m_Image;
 [SerializeField]
 private RectTransform m_RectTransform;
 [SerializeField]
 private Toggle m_Toggle;
 
 public Text text { get { return m_Text; } set { m_Text = value; } }
 public Image image { get { return m_Image; } set { m_Image = value; } }
 public RectTransform rectTransform { get { return m_RectTransform; } set { m_RectTransform = value; } }
 public Toggle toggle { get { return m_Toggle; } set { m_Toggle = value; } }
 
 public virtual void OnPointerEnter(PointerEventData eventData)
 {
 EventSystem.current.SetSelectedGameObject(gameObject);
 }
 
 public virtual void OnCancel(BaseEventData eventData)
 {
 Dropdown dropdown = GetComponentInParent<Dropdown>();
 if (dropdown)
 dropdown.Hide();
 }
 }
 
 [Serializable]
 /// <summary>
 /// Class to store the text and/or image of a single option in the dropdown list.
 /// </summary>
 public class OptionData
 {
 [SerializeField]
 private string m_Text;
 [SerializeField]
 private Sprite m_Image;
 
 /// <summary>
 /// The text associated with the option.
 /// </summary>
 public string text { get { return m_Text; } set { m_Text = value; } }
 
 /// <summary>
 /// The image associated with the option.
 /// </summary>
 public Sprite image { get { return m_Image; } set { m_Image = value; } }
 
 public OptionData()
 {
 }
 
 public OptionData(string text)
 {
 this.text = text;
 }
 
 public OptionData(Sprite image)
 {
 this.image = image;
 }
 
 /// <summary>
 /// Create an object representing a single option for the dropdown list.
 /// </summary>
 /// <param name="text">Optional text for the option.</param>
 /// <param name="image">Optional image for the option.</param>
 public OptionData(string text, Sprite image)
 {
 this.text = text;
 this.image = image;
 }
 }
 
 [Serializable]
 /// <summary>
 /// Class used internally to store the list of options for the dropdown list.
 /// </summary>
 /// <remarks>
 /// The usage of this class is not exposed in the runtime API. It's only relevant for the PropertyDrawer drawing the list of options.
 /// </remarks>
 public class OptionDataList
 {
 [SerializeField]
 private List<OptionData> m_Options;
 
 /// <summary>
 /// The list of options for the dropdown list.
 /// </summary>
 public List<OptionData> options { get { return m_Options; } set { m_Options = value; } }
 
 
 public OptionDataList()
 {
 options = new List<OptionData>();
 }
 }
 
 [Serializable]
 /// <summary>
 /// UnityEvent callback for when a dropdown current option is changed.
 /// </summary>
 public class DropdownEvent : UnityEvent<int> {}
 
 // Template used to create the dropdown.
 [SerializeField]
 private RectTransform m_Template;
 
 /// <summary>
 /// The Rect Transform of the template for the dropdown list.
 /// </summary>
 public RectTransform template { get { return m_Template; } set { m_Template = value; RefreshShownValue(); } }
 
 // Text to be used as a caption for the current value. It's not required, but it's kept here for convenience.
 [SerializeField]
 private Text m_CaptionText;
 
 /// <summary>
 /// The Text component to hold the text of the currently selected option.
 /// </summary>
 public Text captionText { get { return m_CaptionText; } set { m_CaptionText = value; RefreshShownValue(); } }
 
 [SerializeField]
 private Image m_CaptionImage;
 
 /// <summary>
 /// The Image component to hold the image of the currently selected option.
 /// </summary>
 public Image captionImage { get { return m_CaptionImage; } set { m_CaptionImage = value; RefreshShownValue(); } }
 
 [Space]
 
 [SerializeField]
 private Text m_ItemText;
 
 /// <summary>
 /// The Text component to hold the text of the item.
 /// </summary>
 public Text itemText { get { return m_ItemText; } set { m_ItemText = value; RefreshShownValue(); } }
 
 [SerializeField]
 private Image m_ItemImage;
 
 /// <summary>
 /// The Image component to hold the image of the item
 /// </summary>
 public Image itemImage { get { return m_ItemImage; } set { m_ItemImage = value; RefreshShownValue(); } }
 
 [Space]
 
 [SerializeField]
 private int m_Value;
 
 [Space]
 
 // Items that will be visible when the dropdown is shown.
 // We box this into its own class so we can use a Property Drawer for it.
 [SerializeField]
 private OptionDataList m_Options = new OptionDataList();
 
 /// <summary>
 /// The list of possible options. A text string and an image can be specified for each option.
 /// </summary>
 /// <remarks>
 /// This is the list of options within the Dropdown. Each option contains Text and/or image data that you can specify using UI.Dropdown.OptionData before adding to the Dropdown list.
 /// This also unlocks the ability to edit the Dropdown, including the insertion, removal, and finding of options, as well as other useful tools
 /// </remarks>
 /// /// <example>
 /// <code>
 /// //Create a new Dropdown GameObject by going to the Hierarchy and clicking __Create__>__UI__>__Dropdown__. Attach this script to the Dropdown GameObject.
 ///
 /// using UnityEngine;
 /// using UnityEngine.UI;
 /// using System.Collections.Generic;
 ///
 /// public class Example : MonoBehaviour
 /// {
 /// //Use these for adding options to the Dropdown List
 /// Dropdown.OptionData m_NewData, m_NewData2;
 /// //The list of messages for the Dropdown
 /// List<Dropdown.OptionData> m_Messages = new List<Dropdown.OptionData>();
 ///
 ///
 /// //This is the Dropdown
 /// Dropdown m_Dropdown;
 /// string m_MyString;
 /// int m_Index;
 ///
 /// void Start()
 /// {
 /// //Fetch the Dropdown GameObject the script is attached to
 /// m_Dropdown = GetComponent<Dropdown>();
 /// //Clear the old options of the Dropdown menu
 /// m_Dropdown.ClearOptions();
 ///
 /// //Create a new option for the Dropdown menu which reads "Option 1" and add to messages List
 /// m_NewData = new Dropdown.OptionData();
 /// m_NewData.text = "Option 1";
 /// m_Messages.Add(m_NewData);
 ///
 /// //Create a new option for the Dropdown menu which reads "Option 2" and add to messages List
 /// m_NewData2 = new Dropdown.OptionData();
 /// m_NewData2.text = "Option 2";
 /// m_Messages.Add(m_NewData2);
 ///
 /// //Take each entry in the message List
 /// foreach (Dropdown.OptionData message in m_Messages)
 /// {
 /// //Add each entry to the Dropdown
 /// m_Dropdown.options.Add(message);
 /// //Make the index equal to the total number of entries
 /// m_Index = m_Messages.Count - 1;
 /// }
 /// }
 ///
 /// //This OnGUI function is used here for a quick demonstration. See the [[wiki:UISystem|UI Section]] for more information about setting up your own UI.
 /// void OnGUI()
 /// {
 /// //TextField for user to type new entry to add to Dropdown
 /// m_MyString = GUI.TextField(new Rect(0, 40, 100, 40), m_MyString);
 ///
 /// //Press the "Add" Button to add a new entry to the Dropdown
 /// if (GUI.Button(new Rect(0, 0, 100, 40), "Add"))
 /// {
 /// //Make the index the last number of entries
 /// m_Index = m_Messages.Count;
 /// //Create a temporary option
 /// Dropdown.OptionData temp = new Dropdown.OptionData();
 /// //Make the option the data from the TextField
 /// temp.text = m_MyString;
 ///
 /// //Update the messages list with the TextField data
 /// m_Messages.Add(temp);
 ///
 /// //Add the Textfield data to the Dropdown
 /// m_Dropdown.options.Insert(m_Index, temp);
 /// }
 ///
 /// //Press the "Remove" button to delete the selected option
 /// if (GUI.Button(new Rect(110, 0, 100, 40), "Remove"))
 /// {
 /// //Remove the current selected item from the Dropdown from the messages List
 /// m_Messages.RemoveAt(m_Dropdown.value);
 /// //Remove the current selection from the Dropdown
 /// m_Dropdown.options.RemoveAt(m_Dropdown.value);
 /// }
 /// }
 /// }
 /// </code>
 /// </example>
 public List<OptionData> options
 {
 get { return m_Options.options; }
 set { m_Options.options = value; RefreshShownValue(); }
 }
 
 [Space]
 
 // Notification triggered when the dropdown changes.
 [SerializeField]
 private DropdownEvent m_OnValueChanged = new DropdownEvent();
 
 /// <summary>
 /// A UnityEvent that is invoked when when a user has clicked one of the options in the dropdown list.
 /// </summary>
 /// <remarks>
 /// Use this to detect when a user selects one or more options in the Dropdown. Add a listener to perform an action when this UnityEvent detects a selection by the user. See https://unity3d.com/learn/tutorials/topics/scripting/delegates for more information on delegates.
 /// </remarks>
 /// <example>
 /// <code>
 /// //Create a new Dropdown GameObject by going to the Hierarchy and clicking Create>UI>Dropdown. Attach this script to the Dropdown GameObject.
 /// //Set your own Text in the Inspector window
 ///
 /// using UnityEngine;
 /// using UnityEngine.UI;
 ///
 /// public class Example : MonoBehaviour
 /// {
 /// Dropdown m_Dropdown;
 /// public Text m_Text;
 ///
 /// void Start()
 /// {
 /// //Fetch the Dropdown GameObject
 /// m_Dropdown = GetComponent<Dropdown>();
 /// //Add listener for when the value of the Dropdown changes, to take action
 /// m_Dropdown.onValueChanged.AddListener(delegate {
 /// DropdownValueChanged(m_Dropdown);
 /// });
 ///
 /// //Initialise the Text to say the first value of the Dropdown
 /// m_Text.text = "First Value : " + m_Dropdown.value;
 /// }
 ///
 /// //Ouput the new value of the Dropdown into Text
 /// void DropdownValueChanged(Dropdown change)
 /// {
 /// m_Text.text = "New Value : " + change.value;
 /// }
 /// }
 /// </code>
 /// </example>
 public DropdownEvent onValueChanged { get { return m_OnValueChanged; } set { m_OnValueChanged = value; } }
 
 [SerializeField]
 private float m_AlphaFadeSpeed = 0.15f;
 
 /// <summary>
 /// The time interval at which a drop down will appear and disappear
 /// </summary>
 public float alphaFadeSpeed { get { return m_AlphaFadeSpeed; } set { m_AlphaFadeSpeed = value; } }
 
 private GameObject m_Dropdown;
 private GameObject m_Blocker;
 private List<DropdownItem> m_Items = new List<DropdownItem>();
 private TweenRunner<FloatTween> m_AlphaTweenRunner;
 private bool validTemplate = false;
 
 private static OptionData s_NoOptionData = new OptionData();
 
 /// <summary>
 /// The Value is the index number of the current selection in the Dropdown. 0 is the first option in the Dropdown, 1 is the second, and so on.
 /// </summary>
 /// <example>
 /// <code>
 /// //Create a new Dropdown GameObject by going to the Hierarchy and clicking __Create__>__UI__>__Dropdown__. Attach this script to the Dropdown GameObject.
 /// //Set your own Text in the Inspector window
 ///
 /// using UnityEngine;
 /// using UnityEngine.UI;
 ///
 /// public class Example : MonoBehaviour
 /// {
 /// //Attach this script to a Dropdown GameObject
 /// Dropdown m_Dropdown;
 /// //This is the string that stores the current selection m_Text of the Dropdown
 /// string m_Message;
 /// //This Text outputs the current selection to the screen
 /// public Text m_Text;
 /// //This is the index value of the Dropdown
 /// int m_DropdownValue;
 ///
 /// void Start()
 /// {
 /// //Fetch the DropDown component from the GameObject
 /// m_Dropdown = GetComponent<Dropdown>();
 /// //Output the first Dropdown index value
 /// Debug.Log("Starting Dropdown Value : " + m_Dropdown.value);
 /// }
 ///
 /// void Update()
 /// {
 /// //Keep the current index of the Dropdown in a variable
 /// m_DropdownValue = m_Dropdown.value;
 /// //Change the message to say the name of the current Dropdown selection using the value
 /// m_Message = m_Dropdown.options[m_DropdownValue].text;
 /// //Change the onscreen Text to reflect the current Dropdown selection
 /// m_Text.text = m_Message;
 /// }
 /// }
 /// </code>
 /// </example>
 public int value
 {
 get
 {
 return m_Value;
 }
 set
 {
 Set(value);
 }
 }
 /// <summary>
 /// Set index number of the current selection in the Dropdown without invoking onValueChanged callback.
 /// </summary>
 /// <param name="input"> The new index for the current selection. </param>
 public void SetValueWithoutNotify(int input)
 {
 Set(input, false);
 }
 
 void Set(int value, bool sendCallback = true)
 {
 if (Application.isPlaying && (value == m_Value || options.Count == 0))
 return;
 
 m_Value = Mathf.Clamp(value, 0, options.Count - 1);
 RefreshShownValue();
 
 if (sendCallback)
 {
 // Notify all listeners
 UISystemProfilerApi.AddMarker("Dropdown.value", this);
 m_OnValueChanged.Invoke(m_Value);
 }
 }
 
 protected Dropdown()
 {}
 
 protected override void Awake()
 {
 #if UNITY_EDITOR
 if (!Application.isPlaying)
 return;
 #endif
 
 m_AlphaTweenRunner = new TweenRunner<FloatTween>();
 m_AlphaTweenRunner.Init(this);
 
 if (m_CaptionImage)
 m_CaptionImage.enabled = (m_CaptionImage.sprite != null);
 
 if (m_Template)
 m_Template.gameObject.SetActive(false);
 }
 
 protected override void Start()
 {
 base.Start();
 
 RefreshShownValue();
 }
 
 #if UNITY_EDITOR
 protected override void OnValidate()
 {
 base.OnValidate();
 
 if (!IsActive())
 return;
 
 RefreshShownValue();
 }
 
 #endif
 protected override void OnDisable()
 {
 //Destroy dropdown and blocker in case user deactivates the dropdown when they click an option (case 935649)
 ImmediateDestroyDropdownList();
 
 if (m_Blocker != null)
 DestroyBlocker(m_Blocker);
 m_Blocker = null;
 
 base.OnDisable();
 }
 
 /// <summary>
 /// Refreshes the text and image (if available) of the currently selected option.
 /// </summary>
 /// <remarks>
 /// If you have modified the list of options, you should call this method afterwards to ensure that the visual state of the dropdown corresponds to the updated options.
 /// </remarks>
 public void RefreshShownValue()
 {
 OptionData data = s_NoOptionData;
 
 if (options.Count > 0)
 data = options[Mathf.Clamp(m_Value, 0, options.Count - 1)];
 
 if (m_CaptionText)
 {
 if (data != null && data.text != null)
 m_CaptionText.text = data.text;
 else
 m_CaptionText.text = "";
 }
 
 if (m_CaptionImage)
 {
 if (data != null)
 m_CaptionImage.sprite = data.image;
 else
 m_CaptionImage.sprite = null;
 m_CaptionImage.enabled = (m_CaptionImage.sprite != null);
 }
 }
 
 /// <summary>
 /// Add multiple options to the options of the Dropdown based on a list of OptionData objects.
 /// </summary>
 /// <param name="options">The list of OptionData to add.</param>
 /// /// <remarks>
 /// See AddOptions(List<string> options) for code example of usages.
 /// </remarks>
 public void AddOptions(List<OptionData> options)
 {
 this.options.AddRange(options);
 RefreshShownValue();
 }
 
 /// <summary>
 /// Add multiple text-only options to the options of the Dropdown based on a list of strings.
 /// </summary>
 /// <remarks>
 /// Add a List of string messages to the Dropdown. The Dropdown shows each member of the list as a separate option.
 /// </remarks>
 /// <param name="options">The list of text strings to add.</param>
 /// <example>
 /// <code>
 /// //Create a new Dropdown GameObject by going to the Hierarchy and clicking Create>UI>Dropdown. Attach this script to the Dropdown GameObject.
 ///
 /// using System.Collections.Generic;
 /// using UnityEngine;
 /// using UnityEngine.UI;
 ///
 /// public class Example : MonoBehaviour
 /// {
 /// //Create a List of new Dropdown options
 /// List<string> m_DropOptions = new List<string> { "Option 1", "Option 2"};
 /// //This is the Dropdown
 /// Dropdown m_Dropdown;
 ///
 /// void Start()
 /// {
 /// //Fetch the Dropdown GameObject the script is attached to
 /// m_Dropdown = GetComponent<Dropdown>();
 /// //Clear the old options of the Dropdown menu
 /// m_Dropdown.ClearOptions();
 /// //Add the options created in the List above
 /// m_Dropdown.AddOptions(m_DropOptions);
 /// }
 /// }
 /// </code>
 /// </example>
 public void AddOptions(List<string> options)
 {
 for (int i = 0; i < options.Count; i++)
 this.options.Add(new OptionData(options[i]));
 RefreshShownValue();
 }
 
 /// <summary>
 /// Add multiple image-only options to the options of the Dropdown based on a list of Sprites.
 /// </summary>
 /// <param name="options">The list of Sprites to add.</param>
 /// <remarks>
 /// See AddOptions(List<string> options) for code example of usages.
 /// </remarks>
 public void AddOptions(List<Sprite> options)
 {
 for (int i = 0; i < options.Count; i++)
 this.options.Add(new OptionData(options[i]));
 RefreshShownValue();
 }
 
 /// <summary>
 /// Clear the list of options in the Dropdown.
 /// </summary>
 public void ClearOptions()
 {
 options.Clear();
 m_Value = 0;
 RefreshShownValue();
 }
 
 private void SetupTemplate()
 {
 validTemplate = false;
 
 if (!m_Template)
 {
 Debug.LogError("The dropdown template is not assigned. The template needs to be assigned and must have a child GameObject with a Toggle component serving as the item.", this);
 return;
 }
 
 GameObject templateGo = m_Template.gameObject;
 templateGo.SetActive(true);
 Toggle itemToggle = m_Template.GetComponentInChildren<Toggle>();
 
 validTemplate = true;
 if (!itemToggle || itemToggle.transform == template)
 {
 validTemplate = false;
 Debug.LogError("The dropdown template is not valid. The template must have a child GameObject with a Toggle component serving as the item.", template);
 }
 else if (!(itemToggle.transform.parent is RectTransform))
 {
 validTemplate = false;
 Debug.LogError("The dropdown template is not valid. The child GameObject with a Toggle component (the item) must have a RectTransform on its parent.", template);
 }
 else if (itemText != null && !itemText.transform.IsChildOf(itemToggle.transform))
 {
 validTemplate = false;
 Debug.LogError("The dropdown template is not valid. The Item Text must be on the item GameObject or children of it.", template);
 }
 else if (itemImage != null && !itemImage.transform.IsChildOf(itemToggle.transform))
 {
 validTemplate = false;
 Debug.LogError("The dropdown template is not valid. The Item Image must be on the item GameObject or children of it.", template);
 }
 
 if (!validTemplate)
 {
 templateGo.SetActive(false);
 return;
 }
 
 DropdownItem item = itemToggle.gameObject.AddComponent<DropdownItem>();
 item.text = m_ItemText;
 item.image = m_ItemImage;
 item.toggle = itemToggle;
 item.rectTransform = (RectTransform)itemToggle.transform;
 
 // Find the Canvas that this dropdown is a part of
 Canvas parentCanvas = null;
 Transform parentTransform = m_Template.parent;
 while (parentTransform != null)
 {
 parentCanvas = parentTransform.GetComponent<Canvas>();
 if (parentCanvas != null)
 break;
 
 parentTransform = parentTransform.parent;
 }
 
 Canvas popupCanvas = GetOrAddComponent<Canvas>(templateGo);
 popupCanvas.overrideSorting = true;
 popupCanvas.sortingOrder = 30000;
 
 // If we have a parent canvas, apply the same raycasters as the parent for consistency.
 if (parentCanvas != null)
 {
 Component[] components = parentCanvas.GetComponents<BaseRaycaster>();
 for (int i = 0; i < components.Length; i++)
 {
 Type raycasterType = components[i].GetType();
 if (templateGo.GetComponent(raycasterType) == null)
 {
 templateGo.AddComponent(raycasterType);
 }
 }
 }
 else
 {
 GetOrAddComponent<GraphicRaycaster>(templateGo);
 }
 
 GetOrAddComponent<CanvasGroup>(templateGo);
 templateGo.SetActive(false);
 
 validTemplate = true;
 }
 
 private static T GetOrAddComponent<T>(GameObject go) where T : Component
 {
 T comp = go.GetComponent<T>();
 if (!comp)
 comp = go.AddComponent<T>();
 return comp;
 }
 
 /// <summary>
 /// Handling for when the dropdown is initially 'clicked'. Typically shows the dropdown
 /// </summary>
 /// <param name="eventData">The asocciated event data.</param>
 public virtual void OnPointerClick(PointerEventData eventData)
 {
 Show();
 }
 
 /// <summary>
 /// Handling for when the dropdown is selected and a submit event is processed. Typically shows the dropdown
 /// </summary>
 /// <param name="eventData">The asocciated event data.</param>
 public virtual void OnSubmit(BaseEventData eventData)
 {
 Show();
 }
 
 /// <summary>
 /// This will hide the dropdown list.
 /// </summary>
 /// <remarks>
 /// Called by a BaseInputModule when a Cancel event occurs.
 /// </remarks>
 /// <param name="eventData">The asocciated event data.</param>
 public virtual void OnCancel(BaseEventData eventData)
 {
 Hide();
 }
 
 /// <summary>
 /// Show the dropdown.
 ///
 /// Plan for dropdown scrolling to ensure dropdown is contained within screen.
 ///
 /// We assume the Canvas is the screen that the dropdown must be kept inside.
 /// This is always valid for screen space canvas modes.
 /// For world space canvases we don't know how it's used, but it could be e.g. for an in-game monitor.
 /// We consider it a fair constraint that the canvas must be big enough to contain dropdowns.
 /// </summary>
 public void Show()
 {
 if (!IsActive() || !IsInteractable() || m_Dropdown != null)
 return;
 
 // Get root Canvas.
 var list = ListPool<Canvas>.Get();
 gameObject.GetComponentsInParent(false, list);
 if (list.Count == 0)
 return;
 
 // case 1064466 rootCanvas should be last element returned by GetComponentsInParent()
 Canvas rootCanvas = list[list.Count - 1];
 for (int i = 0; i < list.Count; i++)
 {
 if (list[i].isRootCanvas)
 {
 rootCanvas = list[i];
 break;
 }
 }
 
 ListPool<Canvas>.Release(list);
 
 if (!validTemplate)
 {
 SetupTemplate();
 if (!validTemplate)
 return;
 }
 
 m_Template.gameObject.SetActive(true);
 
 // popupCanvas used to assume the root canvas had the default sorting Layer, next line fixes (case 958281 - [UI] Dropdown list does not copy the parent canvas layer when the panel is opened)
 m_Template.GetComponent<Canvas>().sortingLayerID = rootCanvas.sortingLayerID;
 
 // Instantiate the drop-down template
 m_Dropdown = CreateDropdownList(m_Template.gameObject);
 m_Dropdown.name = "Dropdown List";
 m_Dropdown.SetActive(true);
 
 // Make drop-down RectTransform have same values as original.
 RectTransform dropdownRectTransform = m_Dropdown.transform as RectTransform;
 dropdownRectTransform.SetParent(m_Template.transform.parent, false);
 
 // Instantiate the drop-down list items
 
 // Find the dropdown item and disable it.
 DropdownItem itemTemplate = m_Dropdown.GetComponentInChildren<DropdownItem>();
 
 GameObject content = itemTemplate.rectTransform.parent.gameObject;
 RectTransform contentRectTransform = content.transform as RectTransform;
 itemTemplate.rectTransform.gameObject.SetActive(true);
 
 // Get the rects of the dropdown and item
 Rect dropdownContentRect = contentRectTransform.rect;
 Rect itemTemplateRect = itemTemplate.rectTransform.rect;
 
 // Calculate the visual offset between the item's edges and the background's edges
 Vector2 offsetMin = itemTemplateRect.min - dropdownContentRect.min + (Vector2)itemTemplate.rectTransform.localPosition;
 Vector2 offsetMax = itemTemplateRect.max - dropdownContentRect.max + (Vector2)itemTemplate.rectTransform.localPosition;
 Vector2 itemSize = itemTemplateRect.size;
 
 m_Items.Clear();
 
 Toggle prev = null;
 for (int i = 0; i < options.Count; ++i)
 {
 OptionData data = options[i];
 DropdownItem item = AddItem(data, value == i, itemTemplate, m_Items);
 if (item == null)
 continue;
 
 // Automatically set up a toggle state change listener
 item.toggle.isOn = value == i;
 item.toggle.onValueChanged.AddListener(x => OnSelectItem(item.toggle));
 
 // Select current option
 if (item.toggle.isOn)
 item.toggle.Select();
 
 // Automatically set up explicit navigation
 if (prev != null)
 {
 Navigation prevNav = prev.navigation;
 Navigation toggleNav = item.toggle.navigation;
 prevNav.mode = Navigation.Mode.Explicit;
 toggleNav.mode = Navigation.Mode.Explicit;
 
 prevNav.selectOnDown = item.toggle;
 prevNav.selectOnRight = item.toggle;
 toggleNav.selectOnLeft = prev;
 toggleNav.selectOnUp = prev;
 
 prev.navigation = prevNav;
 item.toggle.navigation = toggleNav;
 }
 prev = item.toggle;
 }
 
 // Reposition all items now that all of them have been added
 Vector2 sizeDelta = contentRectTransform.sizeDelta;
 sizeDelta.y = itemSize.y * m_Items.Count + offsetMin.y - offsetMax.y;
 contentRectTransform.sizeDelta = sizeDelta;
 
 float extraSpace = dropdownRectTransform.rect.height - contentRectTransform.rect.height;
 if (extraSpace > 0)
 dropdownRectTransform.sizeDelta = new Vector2(dropdownRectTransform.sizeDelta.x, dropdownRectTransform.sizeDelta.y - extraSpace);
 
 // Invert anchoring and position if dropdown is partially or fully outside of canvas rect.
 // Typically this will have the effect of placing the dropdown above the button instead of below,
 // but it works as inversion regardless of initial setup.
 Vector3[] corners = new Vector3[4];
 dropdownRectTransform.GetWorldCorners(corners);
 
 RectTransform rootCanvasRectTransform = rootCanvas.transform as RectTransform;
 Rect rootCanvasRect = rootCanvasRectTransform.rect;
 for (int axis = 0; axis < 2; axis++)
 {
 bool outside = false;
 for (int i = 0; i < 4; i++)
 {
 Vector3 corner = rootCanvasRectTransform.InverseTransformPoint(corners[i]);
 if ((corner[axis] < rootCanvasRect.min[axis] && !Mathf.Approximately(corner[axis], rootCanvasRect.min[axis])) ||
 (corner[axis] > rootCanvasRect.max[axis] && !Mathf.Approximately(corner[axis], rootCanvasRect.max[axis])))
 {
 outside = true;
 break;
 }
 }
 if (outside)
 RectTransformUtility.FlipLayoutOnAxis(dropdownRectTransform, axis, false, false);
 }
 
 for (int i = 0; i < m_Items.Count; i++)
 {
 RectTransform itemRect = m_Items[i].rectTransform;
 itemRect.anchorMin = new Vector2(itemRect.anchorMin.x, 0);
 itemRect.anchorMax = new Vector2(itemRect.anchorMax.x, 0);
 itemRect.anchoredPosition = new Vector2(itemRect.anchoredPosition.x, offsetMin.y + itemSize.y * (m_Items.Count - 1 - i) + itemSize.y * itemRect.pivot.y);
 itemRect.sizeDelta = new Vector2(itemRect.sizeDelta.x, itemSize.y);
 }
 
 // Fade in the popup
 AlphaFadeList(m_AlphaFadeSpeed, 0f, 1f);
 
 // Make drop-down template and item template inactive
 m_Template.gameObject.SetActive(false);
 itemTemplate.gameObject.SetActive(false);
 
 m_Blocker = CreateBlocker(rootCanvas);
 }
 
 /// <summary>
 /// Create a blocker that blocks clicks to other controls while the dropdown list is open.
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to obtain a blocker GameObject.
 /// </remarks>
 /// <param name="rootCanvas">The root canvas the dropdown is under.</param>
 /// <returns>The created blocker object</returns>
 protected virtual GameObject CreateBlocker(Canvas rootCanvas)
 {
 // Create blocker GameObject.
 GameObject blocker = new GameObject("Blocker");
 
 // Setup blocker RectTransform to cover entire root canvas area.
 RectTransform blockerRect = blocker.AddComponent<RectTransform>();
 blockerRect.SetParent(rootCanvas.transform, false);
 blockerRect.anchorMin = Vector3.zero;
 blockerRect.anchorMax = Vector3.one;
 blockerRect.sizeDelta = Vector2.zero;
 
 // Make blocker be in separate canvas in same layer as dropdown and in layer just below it.
 Canvas blockerCanvas = blocker.AddComponent<Canvas>();
 blockerCanvas.overrideSorting = true;
 Canvas dropdownCanvas = m_Dropdown.GetComponent<Canvas>();
 blockerCanvas.sortingLayerID = dropdownCanvas.sortingLayerID;
 blockerCanvas.sortingOrder = dropdownCanvas.sortingOrder - 1;
 
 // Find the Canvas that this dropdown is a part of
 Canvas parentCanvas = null;
 Transform parentTransform = m_Template.parent;
 while (parentTransform != null)
 {
 parentCanvas = parentTransform.GetComponent<Canvas>();
 if (parentCanvas != null)
 break;
 
 parentTransform = parentTransform.parent;
 }
 
 // If we have a parent canvas, apply the same raycasters as the parent for consistency.
 if (parentCanvas != null)
 {
 Component[] components = parentCanvas.GetComponents<BaseRaycaster>();
 for (int i = 0; i < components.Length; i++)
 {
 Type raycasterType = components[i].GetType();
 if (blocker.GetComponent(raycasterType) == null)
 {
 blocker.AddComponent(raycasterType);
 }
 }
 }
 else
 {
 // Add raycaster since it's needed to block.
 GetOrAddComponent<GraphicRaycaster>(blocker);
 }
 
 
 // Add image since it's needed to block, but make it clear.
 Image blockerImage = blocker.AddComponent<Image>();
 blockerImage.color = Color.clear;
 
 // Add button since it's needed to block, and to close the dropdown when blocking area is clicked.
 Button blockerButton = blocker.AddComponent<Button>();
 blockerButton.onClick.AddListener(Hide);
 
 return blocker;
 }
 
 /// <summary>
 /// Convenience method to explicitly destroy the previously generated blocker object
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to dispose of a blocker GameObject that blocks clicks to other controls while the dropdown list is open.
 /// </remarks>
 /// <param name="blocker">The blocker object to destroy.</param>
 protected virtual void DestroyBlocker(GameObject blocker)
 {
 Destroy(blocker);
 }
 
 /// <summary>
 /// Create the dropdown list to be shown when the dropdown is clicked. The dropdown list should correspond to the provided template GameObject, equivalent to instantiating a copy of it.
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to obtain a dropdown list GameObject.
 /// </remarks>
 /// <param name="template">The template to create the dropdown list from.</param>
 /// <returns>The created drop down list gameobject.</returns>
 protected virtual GameObject CreateDropdownList(GameObject template)
 {
 return (GameObject)Instantiate(template);
 }
 
 /// <summary>
 /// Convenience method to explicitly destroy the previously generated dropdown list
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to dispose of a dropdown list GameObject.
 /// </remarks>
 /// <param name="dropdownList">The dropdown list GameObject to destroy</param>
 protected virtual void DestroyDropdownList(GameObject dropdownList)
 {
 Destroy(dropdownList);
 }
 
 /// <summary>
 /// Create a dropdown item based upon the item template.
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to obtain an option item.
 /// The option item should correspond to the provided template DropdownItem and its GameObject, equivalent to instantiating a copy of it.
 /// </remarks>
 /// <param name="itemTemplate">e template to create the option item from.</param>
 /// <returns>The created dropdown item component</returns>
 protected virtual DropdownItem CreateItem(DropdownItem itemTemplate)
 {
 return (DropdownItem)Instantiate(itemTemplate);
 }
 
 /// <summary>
 /// Convenience method to explicitly destroy the previously generated Items.
 /// </summary>
 /// <remarks>
 /// Override this method to implement a different way to dispose of an option item.
 /// Likely no action needed since destroying the dropdown list destroys all contained items as well.
 /// </remarks>
 /// <param name="item">The Item to destroy.</param>
 protected virtual void DestroyItem(DropdownItem item)
 {}
 
 // Add a new drop-down list item with the specified values.
 private DropdownItem AddItem(OptionData data, bool selected, DropdownItem itemTemplate, List<DropdownItem> items)
 {
 // Add a new item to the dropdown.
 DropdownItem item = CreateItem(itemTemplate);
 item.rectTransform.SetParent(itemTemplate.rectTransform.parent, false);
 
 item.gameObject.SetActive(true);
 item.gameObject.name = "Item " + items.Count + (data.text != null ? ": " + data.text : "");
 
 if (item.toggle != null)
 {
 item.toggle.isOn = false;
 }
 
 // Set the item's data
 if (item.text)
 item.text.text = data.text;
 if (item.image)
 {
 item.image.sprite = data.image;
 item.image.enabled = (item.image.sprite != null);
 }
 
 items.Add(item);
 return item;
 }
 
 private void AlphaFadeList(float duration, float alpha)
 {
 CanvasGroup group = m_Dropdown.GetComponent<CanvasGroup>();
 AlphaFadeList(duration, group.alpha, alpha);
 }
 
 private void AlphaFadeList(float duration, float start, float end)
 {
 if (end.Equals(start))
 return;
 
 FloatTween tween = new FloatTween {duration = duration, startValue = start, targetValue = end};
 tween.AddOnChangedCallback(SetAlpha);
 tween.ignoreTimeScale = true;
 m_AlphaTweenRunner.StartTween(tween);
 }
 
 private void SetAlpha(float alpha)
 {
 if (!m_Dropdown)
 return;
 CanvasGroup group = m_Dropdown.GetComponent<CanvasGroup>();
 group.alpha = alpha;
 }
 
 /// <summary>
 /// Hide the dropdown list. I.e. close it.
 /// </summary>
 public void Hide()
 {
 if (m_Dropdown != null)
 {
 AlphaFadeList(m_AlphaFadeSpeed, 0f);
 
 // User could have disabled the dropdown during the OnValueChanged call.
 if (IsActive())
 StartCoroutine(DelayedDestroyDropdownList(m_AlphaFadeSpeed));
 }
 if (m_Blocker != null)
 DestroyBlocker(m_Blocker);
 m_Blocker = null;
 Select();
 }
 
 private IEnumerator DelayedDestroyDropdownList(float delay)
 {
 yield return new WaitForSecondsRealtime(delay);
 ImmediateDestroyDropdownList();
 }
 
 private void ImmediateDestroyDropdownList()
 {
 for (int i = 0; i < m_Items.Count; i++)
 {
 if (m_Items[i] != null)
 DestroyItem(m_Items[i]);
 }
 m_Items.Clear();
 if (m_Dropdown != null)
 DestroyDropdownList(m_Dropdown);
 m_Dropdown = null;
 }
 
 // Change the value and hide the dropdown.
 private void OnSelectItem(Toggle toggle)
 {
 if (!toggle.isOn)
 toggle.isOn = true;
 
 int selectedIndex = -1;
 Transform tr = toggle.transform;
 Transform parent = tr.parent;
 for (int i = 0; i < parent.childCount; i++)
 {
 if (parent.GetChild(i) == tr)
 {
 // Subtract one to account for template child.
 selectedIndex = i - 1;
 break;
 }
 }
 
 if (selectedIndex < 0)
 return;
 
 value = selectedIndex;
 Hide();
 }
 }
 }

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