VisualElement layout/content rects contain NaN values initially & transform.scale breaks children

Hi,

I have a system built with UIElements in which I instantiate a VisualElement tree (from Uxml/Uss) in response to a button press and place it within my window hierarchy. I am then animating this VisualElement on-screen using the Scheduler API. However, I'm come across two difficullties, which I'm not sure how to resolve.

1. When a VisualElement is initialized, its layout/content rects contain NaN values. However, I need the element's rect immediately so I can calculate its size and perform my animation correctly (sliding off-screen to on-screen etc.). How can I force the VisualElement to calculate its rect after initialization? I have tried using the MarkDirtyRepaint method but as the documentation states, this waits until the next frame so the values are still NaN. In case it's relevant, the layout of the element is determined by a simple style sheet, like so:

Code (CSharp):

1. .fit-to-parent
2. {
3.     position: absolute;
4.     left: 0;
5.     top: 0;
6.     right: 0;
7.     bottom: 0;
8. }

2. I can animate a VisualElement's transform.position and transform.rotation with no problems, however when I animate its transform.scale property, all of the element's children appear to break. For example, a child label doesn't render anymore and a child button's hit state becomes the entire window. Is there something else I need to do when altering a VisualElement's transform.scale property (to make it recalculate its rect perhaps)?

Any help would be much appreciated. Thanks.
-andy.

 

Thanks a lot @patrickf. I'll file a bug on the scaling issue.

Regarding the force layout, could it be something the UIElements team might consider exposing in a future version? For example, the current UI system has the method LayoutRebuilder.ForceRebuildLayoutImmediate for "special layout calculation needs". Additionally, take a platform like iOS - the UIView class has the setNeedsLayout()/layoutIfNeeded() methods for this purpose. I appreciate the GeometryChangedEvent/MarkDirtyRepaint will be sufficient for many use-cases but there are instances where a user may need to make a layout happen immediately, such as in the frame of instantiating a child element to make a calculation about its rect.

 

I am running into a related issue.

I have a overlay Label with position set to absolute. I update the text. Immediately after I need to know how wide the label has become, so I can align it to the left side of another element. It would be silly to update the entire UI since I only care about the label.

Is there a way around this?

EDIT:
I have posted in a new thread:
https://forum.unity.com/threads/width-of-label.732476/

 

One problem of practicality with GeometryChangeEvent is the margin of the item doesn't seem to have been set yet. As well as the padding of the element that the element sits inside of.


Either that or

style.paddingLeft.value.value 

and

style.marginRight.value.value

are bugged.

 

Thanks, yeah, I was able to eventually figure that out.

While this works, this API smells.

I see IComputedStyle, IStyle, IResolvedStyle, and ICustomStyle though I think IComputedStyle is a typo of some sort cause it's only mentioned on https://docs.unity3d.com/ScriptReference/UIElements.IStyle.html

While I am sure IStyle has a purpose, this naming is so obviously backward. I implore Unity devs to be more thoughtful in the future.