How do I get the literal width of a RectTransform?

Question

I'm trying to use the the width of a UI object to define the size of future UI objects. I have read other questions which have given the answer RectTransform.rect.width. This returns a negative value in my case (because of anchoring). Is there a function to get the real / literal width of the object I am looking at or does it need to be calculated based on the anchor positions?

Answer 1

Best Answer

Answer by Elum224 · Apr 14, 2015 at 09:15 AM

My solution is to use a coroutine to wait until the next frame for when the objects have finished resizing themselves and use RectTransform.sizeDelta.x or RectTransform.rect.width according to need.

Add comment · Show 2 · Share

dappledore · Oct 22, 2016 at 10:52 PM 0

Share

 public IEnumerator SetGridWidth() {
         yield return new WaitForEndOfFrame();
         GridWidth = transform.GetComponent<RectTransform> ().sizeDelta.x;
     }

Reaper93 · Mar 15, 2019 at 11:50 AM 0

Share

That helped a ton! Thanks! That was so not obvious. I would have no idea what is happening if not your explanation

Answer 2

Answer by DiegoSLTS · Apr 13, 2015 at 06:21 PM

http://docs.unity3d.com/ScriptReference/RectTransform-rect.html

 aRectTransformReference.rect.width

Add comment · Show 1 · Share

BryanTaiNexusMedia · Mar 20, 2019 at 06:15 PM 0

Share

I'm using a Canvas with Render $$anonymous$$ode: Screen Space - Camera and this works perfectly for me

Answer 3

rect.width only works if RectTransform.anchorMin.x and RectTransform.anchorMax.x are the same (overlapping). If they are different (i.e., if the object stretches on X when its parent changes width) then rect.width will contain the width of the object relative to its parent width. Since the object is typically smaller than its parent, this value will be negative.

You could try getting the bounds of the game object:

 Renderer renderer = obj.GetComponent<Renderer>();
 Bounds bounds = renderer.bounds;
 float width = bounds.size.x;

but for a UI Panel object, the GetComponent() call returns null, even if the panel has an Image component in it and that image component is enabled.

Alternately, you could try calling RectTransform.GetWorldCorners(). You pass it an array of four Vector3s and you get back the world coordinates of the four corners. You can then subtract X coords to get the width.

Be aware that this stuff only works if the object is in the scene or if the object does not stretch. If your script is attached to a stretchable object that gets dynamically instantiated at run time, you can't get its dimensions in Start() because it doesn't have a parent object yet and consequently hasn't been sized to fit anything (you'll just get the original width or height of the prefab).

Answer 4

Answer by strider2k · May 07, 2015 at 06:26 AM

The width and height of a RectTransform can be <= 0 if stretching by width or height is set in the Inspector. The rect and sizeDelta will return values such as: rect: (x:0.00, y:36.00, width:0.00, height:-72.00) sizeDelta: (0.0, -72.0)

even after Canvas.ForceUpdateCanvases() and calling a coroutine.

Add comment · Share

Answer 5

Answer by fermmmm · May 12, 2016 at 07:56 AM

Size is always relative to anchors does not matter if it comes from RectTransform.rect.width or RectTransform.SizeDelta. Try the "Rect Transform Extended" asset. You can get the size relative to the parent size (ignoring anchors) and other stuff that should come with Unity:

https://www.assetstore.unity3d.com/#!/content/41927

Add comment · Show 1 · Share

meat5000 ♦ · May 12, 2016 at 07:59 AM 0

Share

No more Adverts please @fermmmm

How do I get the literal width of a RectTransform?

6 Replies

Your answer

Follow this Question

Related Questions