How do you get the parent canvas?

Is there a simple way to get the parent canvas of a UI element?

Because for functions like:

Code (CSharp):

1.         RectTransformUtility.ScreenPointToLocalPointInRectangle(colorpad.rectTransform,Input.mousePosition,Camera.main,out localPoint);
2.  

you need to know whether the canvas is in Overlay mode or Camera mode. In order to either put Camera.main or null in the field.

Or am I missing something? I don't want to put a public variable Canvas because I am making a prefab that can be dropped onto a canvas so it has to be defined only in the script.

Or is there a way of using RectTransformUtility.ScreenPointToLocalPointInRectangle without having to get a reference to the canvas object to see what mode it is in. Really I'd like something like Input.camera to tell you how to interpret Input.mousePosition.

At the moment I'm using this recursive function:

Code (CSharp):

1.     void getCanvas(GameObject g){
2.         if(g.GetComponent<Canvas>()!=null) {
3.             canvas=g.GetComponent<Canvas>();
4.             return;
5.         }else{
6.             if(g.transform.parent!=null){
7.                 getCanvas (g.transform.parent.gameObject);
8.             }
9.         }
10.     }

 

Have you considered GetComponentInParent<Canvas>() to replace your recursive lookup?

 

Beat me to it @mh114
This is exactly how to do it.
You can combine it with the tests above (parent == null) if you want the top most parent canvas, remembering that Canvases can be nested.

If you have many Canvases, consider tagging them and using "GameObject.FindGameObjectWithTag("CanvasName");"

 

Ah. That sounds much simpler! Thanks.

 

GetComponentsInParents is recursive so topmost canvas is

Code (CSharp):

1. Canvas[] c = GetComponentsInParents<Canvas>();
2. Canvas topmost = c[c.Length-1];

 

Did you make that up? Or has there actually been a GetComponentsInParents in the past?

 

There is a typo in the function name, it is GetComponentsInParent(), not *Parents, but it exists at least since Unity 4.5. So along the lines of laurentlavigne:

Code (CSharp):

1. public static Canvas GetTopmostCanvas(Component component) {
2.     Canvas[] parentCanvases = component.GetComponentsInParent<Canvas>();
3.     if (parentCanvases != null && parentCanvases.Length > 0) {
4.         return parentCanvases[parentCanvases.Length - 1];
5.     }
6.     return null;
7. }

 

Depending on your layout, if the canvas is the top parent you should be able to do

Code (CSharp):

1. transform.root.GetComponent<Canvas>();

I'm pretty sure I used this somewhere for something.

 

So maybe you could do this then:

Good idea! In case it were not the top one, you can do:

Code (CSharp):

1. Canvas topmostCanvas = transform.root.GetComponentInChildren<Canvas>();

The only problem is that if there are branches in the hierarchy and different branches have Canvases, it might not be the Canvas of your transform.

 

I think this is the cleanest and the most reusable way. There was just a tiny syntax issue.

Code (CSharp):

1. Canvas[] c = GetComponentsInParent<Canvas>();
2. Canvas topMostCanvas = c[c.Length - 1];

 

What about this:

Code (CSharp):

1. private static Canvas GetRootCanvas(this RectTransform rectTransform)
2. {
3.     Canvas canvas = rectTransform.GetComponentInParent<Canvas>();
4.  
5.     if (canvas)
6.         return canvas.isRootCanvas ? canvas : canvas.rootCanvas;
7.     else
8.         return null;
9. }

Not the better option (because it also iterates over all hierarchy), but it may be useful for someone.