Is It Possible To Design A Custom Control In UI Builder and Access the Components in C#?

Unity Engine
,
1

Greetings,

I am building a custom UI Control in UI Toolkit. I designed it in UI Builder using visual elements, labels, etc. and set their colors and other attributes. The control looks great in UI builder. Then I created a class and added the following code:

public class PanelApplicationSection : VisualElement { #region Boilerplate for showing up in the UI Builder. //[UnityEngine.Scripting.Preserve] internal new class UxmlFactory : UxmlFactory { } internal new class UxmlTraits : VisualElement.UxmlTraits { } public PanelApplicationSection() { //VisualTreeAsset asset = AssetDatabase.LoadAssetAtPath( // "Assets/Resources/UserInterface/ScreenHome.uxml"); //VisualTreeAsset asset = (VisualTreeAsset)Resources.Load("UserInterface/ScreenHome.uxml"); //asset.CloneTree(this); } #endregion // Fields private VisualElement panelContainer => this.Q("panel_container"); private Label sectionTitle => this.Q("section_title"); private Label sectionTypeTitle => this.Q("section_type_title"); private VisualElement icon => this.Q("icon"); private VisualElement bottonBanner => this.Q("bottom_banner"); private Button buttonPlay => this.Q("button_play");

// Properties
public VisualElement PanelContainer
{
get { return panelContainer; }
}
}

It doesn’t work. The custom control when added to another Uxml document in UI Builder just looks like a blank white area. None of the elements (e.g., labels, visual elements, images, etc.) show up.

I have looked at several YouTube videos and they seem to add elements in code first. I want to design it in UI Builder, then add the coding.

Any idea how I can make them shown up or how I can make my custom UI controller work?

Thanks

2

Hi,

See the following documentation Unity - Manual: Load UXML and USS C# scripts, more specifically the section Use a Resources folder.

3

I looked at it and it was very informative and I made some changess, but it still will not work. I added the following to the constructor of my class:

VisualTreeAsset asset = Resources.Load<VisualTreeAsset>("/UserInterface/ScreenHome.uxml");

asset.CloneTree(this);

However, it keeps telling me that the asset is null. From the console:
NullReferenceException: Object reference not set to an instance of an object
PanelApplicationSection…ctor () (at Assets/Resources/UserInterface/PanelApplicationSection.cs:18)

Line 18 is the line "asset.CloneTree(this);

Should that code not be in the constructor and somewhere else?

Thanks.

4

It just means the asset couldn’t be loaded or wasn’t loaded. Either because the path is wrong, the asset is not in a Resources folder, etc.

5

That’s what I suspected also. I checked the path and corrected the name but it still doesn’t work. It still says the asset is null. I am really trying to figure it out.

6

You were right. It works now. The problem was I had the “.uxml” in the path. Unity doesn’t like that. So once I removed it, it worked.

Thanks for your suggestion.

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