Update layout when textmeshpro font size change

[thelwh]

I want to change the font size of TextMeshProUGUI and keep the recttransform of textmeshpro fit the text size just like ContentSizeFitter.
I found when the textmeshpro gameobject active state change and layout refresh,text transform will fit text size,so I think it's no need to add the ContentSizeFitter component.
I try to call FlexLayout.RefreshRootLayoutImmediate() after change the font size,but it only work the first time.When I change the font size and call FlexLayout.RefreshRootLayoutImmediate() again,it seems no longer work.
I also try FlexLayout.RefreshRootLayout(),and it work in the case of setting the font size smaller,but when set the font size bigger the layout is incorrect.
So please tell me what is the correct way to achieve it.

[gilzoide]

Hey @thelwh, thanks for the question.

Short answer

Use a ContentSizeFitter, it should just work.

Long answer

The library used in this package, Yoga, has this thing called the "measure function". Measure functions are used by Yoga to ask us what's the size of the nodes, for example how big a text or image is.

In our case, we are using Unity UI as nodes, so we use Unity UI's layout API in our measure function, more specifically LayoutUtility.GetPreferredWidth and LayoutUtility.GetPreferredHeight.

unity-flex-ui/Runtime/FlexLayout.cs

Lines 759 to 790 in 30ea7a5

	private static Vector2 RectTransformMeasureFunc(IntPtr nodePtr, float width, MeasureMode widthMode, float height, MeasureMode heightMode)
	{
	var node = new YGNode(nodePtr);
	RectTransform rectTransform = node.GetContext<RectTransform>();
	switch (widthMode)
	{
	case MeasureMode.Undefined:
	width = LayoutUtility.GetPreferredWidth(rectTransform);
	break;
	case MeasureMode.AtMost:
	width = Mathf.Min(width, LayoutUtility.GetPreferredWidth(rectTransform));
	break;
	default:
	break;
	}
	switch (heightMode)
	{
	case MeasureMode.Undefined:
	height = LayoutUtility.GetPreferredHeight(rectTransform);
	break;
	case MeasureMode.AtMost:
	height = Mathf.Min(height, LayoutUtility.GetPreferredHeight(rectTransform));
	break;
	default:
	break;
	}
	return new Vector2(width, height);
	}

For texts in Unity UI (both the legacy Text and TextMeshProUGUI), its preferred size only matches the content size automatically after updates if you add a ContentSizeFitter, so you should just add it and it should just work.

[thelwh]

Thanks for your reply.
I try to add ContentSizeFitter to text object, but when the font size set bigger, the text object layout would incorrect ,and next frame it fix the layout automatically.So it look like joggle when font size change.
I solve the problem by use LayoutRebuilder.ForceRebuildLayoutImmediate after change font size.Hope it would help someone.