[游戏开发]UIElement 自定义VisualElement

UXML 格式 - Unity 手册 (unity3d.com)

创建自定义VisualElement的类StatusBar，并继承自VisualElement。

using UnityEditor;
using UnityEngine.UIElements;

public class StatusBar : VisualElement
{
    private Label _descriptionLabel = default;
    public string Discription
    {
        get => _descriptionLabel.text;
        set => _descriptionLabel.text = value;
    }
    
    //..............................
    //这里是uxml的路径
    private const string UXML_PATH = "Assets/Editor/StatusBar.uxml";
    
    public StatusBar()
    {
        VisualTreeAsset template = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>(UXML_PATH);
        template.CloneTree(this);
        Init();
    }
    
    public void Init()
    {
        //设置好Label变量
        _descriptionLabel = this.Q<Label>("description");
    }

    
    //
    public new class UxmlFactory : UxmlFactory<StatusBar, Traits> {}

    public class Traits : UxmlTraits
    {
        //绑定所需的Uxml属性
        readonly UxmlStringAttributeDescription _description
            = new UxmlStringAttributeDescription {name = "showText"};

        public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
        {
            base.Init(ve, bag, cc);

            StatusBar statusBar = ve as StatusBar;
            statusBar.Discription = _description.GetValueFromBag(bag, cc);
        }
    }
}

Statusbar的UXML文件定义如下。

<?xml version="1.0" encoding="utf-8"?>
<UXML
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="UnityEngine.UIElements"
    xsi:noNamespaceSchemaLocation="../UIElementsSchema/UIElements.xsd"
    xsi:schemaLocation="UnityEngine.UIElements ../UIElementsSchema/UnityEngine.UIElements.xsd">
 
    <Label name="description" text="helloWorld"/>
 
</UXML>

这里设置Label实际上是对StatusBar中的定义：

private Label _descriptionLabel = default;

使用这个自定义的VisualElement的TestWindow的UXML定义如下。

<ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements">
    <StatusBar showText="Test"/>
</ui:UXML>

在最后显示时看到显示的Label上的文本是Test，说明TestWindow.uxml中的定义会覆盖原本引用的StatusBar.uxml中的定义。