StretchToParentSize only validate at initialize stage?

Code (CSharp):

1. using UnityEditor;
2. using UnityEngine;
3. using UnityEngine.Experimental.UIElements;
4. using UnityEditor.Experimental.UIElements;
5.  
6. public class TestWindow : EditorWindow
7. {
8.     [MenuItem("Window/UIElements/TestWindow")]
9.     public static void ShowExample()
10.     {
11.         TestWindow wnd = GetWindow<TestWindow>();
12.         wnd.titleContent = new GUIContent("LineView");
13.     }
14.  
15.     public void OnEnable()
16.     {
17.         VisualElement root = this.GetRootVisualContainer();
18.         VisualElement label = new VisualElement
19.         {
20.             style = {
21.                 backgroundColor=Color.red
22.             }
23.         };
24.         var btn = new Button(() => {
25.             label.StretchToParentSize();
26.         });
27.         root.Add(btn);
28.         root.Add(label);
29.     }
30. }

click the button, the label not stretch.
if move it beneath at construct function, the label will be stretch. why?

 

Code (CSharp):

1. using UnityEditor;
2. using UnityEngine;
3. using UnityEngine.Experimental.UIElements;
4. using UnityEngine.Experimental.UIElements.StyleEnums;
5. using UnityEditor.Experimental.UIElements;
6.  
7.  
8. public class TestWindow : EditorWindow
9. {
10.     [MenuItem("Window/UIElements/TestWindow")]
11.     public static void ShowExample()
12.     {
13.         TestWindow wnd = GetWindow<TestWindow>();
14.         wnd.titleContent = new GUIContent("TestWindow");
15.     }
16.  
17.     public void OnEnable()
18.     {
19.         // Each editor window contains a root VisualElement object
20.         VisualElement root = this.GetRootVisualContainer();
21.  
22.         var ve = new VisualElement
23.         {
24.             style = {
25.                 backgroundColor = Color.red,
26.                 width = 10,
27.                 height = 10
28.             }
29.         };
30.  
31.         root.Add(ve);
32.  
33.         var btn = new Button(() => {
34.             ve.ResetPositionProperties();
35.             ve.style.positionType = PositionType.Absolute;
36.             ve.style.positionLeft = 10;
37.             ve.style.positionTop = 10;
38.             ve.style.positionRight = 10;
39.             ve.style.positionBottom = 10;
40.         });
41.         root.Add(btn);
42.     }
43. }

 

i want change it at runtime, maybe onetime use width,height,positionleft,positiontop
another time use pos left, top, right, bottom.
positionleft, right, top, bottom, if any one is zero. it wont effective.

 

The bug you're encountering only happen when the position-left/right/top/bottom are set to 0 at initialization.
Once they've been set to any other value you should be able to set them back to 0 without any issue.

In this case if you add the "stretch" class like above you're still free to change the value at runtime afterward and you'll be able to reset them to 0 if needed.

 

Using style = { } we can set things like backgroundColor , width, height, etc programmatically. How would you set a hover property for a button programmatically?

 

I figured out a way to do it.... In my stylesheet, I had a style defined for the toolbar item as .toolbaritem {}, one for the button as Button.toolbaritem {} and another one for hover Button:hover {} . Then in the C# code, I called

Code (CSharp):

1. Button btn = new UnityEngine.UIElements.Button() { style = { backgroundImage = tex } };
2. btn.AddToClassList("toolbaritem");

It took me an hour of searching and trial and error to figure out that you need to use "toolbaritem" and NOT ".toolbaritem" (that "." makes a huge difference). Maybe this would have been obvious to a webdev expert, but it wasn't to me. I am looking forward to some UI Toolkit documentation . jonathanma_unity's post above where he used AddToClassList("stretch") is what tipped me off that I should try it without the period, so thanks jonathanma!

 

Thanks 1000x uDamian! That's a good tip - I'll remove the Button specifier.

You're right, there is documentation... I misspoke there. However, I couldn't find any documentation on the AddToClassList() function and how to use it. I kinda just guessed that it corresponded to the "Add Style Class to List" button on the "Style Class List" section in the Inspector on UIBuilder, and googling brought me to this forum page. In UIBuilder the period precedes the class string, so I thought that it would be the same for AddToClassList(). I used the search box in the documentation and also went to the definition of AddToClassList() in the code, but neither had a description of what the function does or what parameter to pass it.

Anyway, so far the UI Toolkit seems to be working pretty well. I'm looking forward to trying it with the new input system soon.