Best algorithm to clamp a UI window within the canvas?

Basically just what the title says. I'm having trouble developing a non-complicated algorithm for keeping a window (whose position is set in script, tracking objects in the scene) within the bounds of the canvas. Does anyone have a good algorithm for this?

 

Wouldn't a simple check for if (transform.localPosition.x < 0) transform.localPosition.x = 0 work? Is there something specific about canvas that makes it tricky?

 

That only works on the anchoredPosition of the window, not all sides of the rectangle.

 

The UIDragPanel ClampToWindow() from the tutorial project doesn't work?

Code (csharp):

1.     // Clamp panel to area of parent
2.     void ClampToWindow()
3.     {
4.         Vector3 pos = panelRectTransform.localPosition;
5.  
6.         Vector3 minPosition = parentRectTransform.rect.min - panelRectTransform.rect.min;
7.         Vector3 maxPosition = parentRectTransform.rect.max - panelRectTransform.rect.max;
8.  
9.         pos.x = Mathf.Clamp(panelRectTransform.localPosition.x, minPosition.x, maxPosition.x);
10.         pos.y = Mathf.Clamp(panelRectTransform.localPosition.y, minPosition.y, maxPosition.y);
11.  
12.         panelRectTransform.localPosition = pos;
13.     }

 

I always forget that these things have a 'rect' property.... That's the magic bit I was missing. Thanks