内容简介：截止目前Unity2018.3.3版本下的UGUI Dropdown依旧如题。当然，目前的功能是基本能满足大部分场景应用的。但如果你需要每次点击都有回调的话，那么，你就需要扩展或者重写Dropdown。
截止目前Unity2018.3.3版本下的UGUI Dropdown依旧如题。
当然，目前的功能是基本能满足大部分场景应用的。
但如果你需要每次点击都有回调的话，那么，你就需要扩展或者重写Dropdown。
我们新建一个类：DropdownExtent，并且让它继承Dropdown，然后重写OnPointerClick:
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class DropdownExtend : Dropdown
{
public bool AlwaysCallback = false;
public void Show()
{
base.Show();
var toggleRoot = transform.Find("Dropdown List/Viewport/Content");
var toggleList = toggleRoot.GetComponentsInChildren<Toggle>(false);
foreach (var temp in toggleList)
{
temp.onValueChanged.RemoveAllListeners();
temp.isOn = false;
var temp1 = temp;
temp.onValueChanged.AddListener(x => OnSelectItemExtend(temp1));
}
}
public override void OnPointerClick(PointerEventData eventData)
{
Show();
}
public void OnSelectItemExtend(Toggle toggle)
{
if (!toggle.isOn)
{
toggle.isOn = true;
return;
}
var selectedIndex = -1;
var tr = toggle.transform;
var parent = tr.parent;
for (var i = 0; i < parent.childCount; i++)
{
if (parent.GetChild(i) != tr) continue;
selectedIndex = i - 1;
break;
}
if (selectedIndex < 0)
return;
if (value == selectedIndex && AlwaysCallback)
onValueChanged.Invoke(value);
else
value = selectedIndex;
Hide();
}
}
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class DropdownExtend : Dropdown
{
public bool AlwaysCallback = false;
public void Show()
{
base.Show();
var toggleRoot = transform.Find("Dropdown List/Viewport/Content");
var toggleList = toggleRoot.GetComponentsInChildren<Toggle>(false);
foreach (var temp in toggleList)
{
temp.onValueChanged.RemoveAllListeners();
temp.isOn = false;
var temp1 = temp;
temp.onValueChanged.AddListener(x => OnSelectItemExtend(temp1));
}
}
public override void OnPointerClick(PointerEventData eventData)
{
Show();
}
public void OnSelectItemExtend(Toggle toggle)
{
if (!toggle.isOn)
{
toggle.isOn = true;
return;
}
var selectedIndex = -1;
var tr = toggle.transform;
var parent = tr.parent;
for (var i = 0; i < parent.childCount; i++)
{
if (parent.GetChild(i) != tr) continue;
selectedIndex = i - 1;
break;
}
if (selectedIndex < 0)
return;
if (value == selectedIndex && AlwaysCallback)
onValueChanged.Invoke(value);
else
value = selectedIndex;
Hide();
}
}
测试代码：
using UnityEngine;
public class Test : MonoBehaviour
{
public DropdownExtend _dropdownEx;
void Start()
{
_dropdownEx.AlwaysCallback = true;
_dropdownEx.onValueChanged.AddListener(OnChanged);
}
private void OnChanged(int index)
{
Debug.Log(index);
}
}
using UnityEngine;
public class Test : MonoBehaviour
{
public DropdownExtend _dropdownEx;
void Start()
{
_dropdownEx.AlwaysCallback = true;
_dropdownEx.onValueChanged.AddListener(OnChanged);
}
private void OnChanged(int index)
{
Debug.Log(index);
}
}
说明：
- 扩展类将替换掉原来的Dropdown组件，重新关联属性面板上的引用。
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