Question by 11tomi12 · Feb 01, 2019 at 07:32 AM · ui recttransform anchor boundary

Positioning UI object inside screen space

I am implementing a speech bubble in a 2D game that positions itself over a character speaking. I would like it to stay within the screen space and implemented a function for this as shown below. It does work to some degree but I am struggling with calculating the position of the Main object according to the boundaries of the child speech bubble object. The structure is as following:

 Canvas
     Main speech bubble Rectangle (that needs to be moved)
         Bubble arrow (doesnt resize with text)
         Bubble Rectangle(has bubble image and resizes according to text, used for out of camera check)
             Text

And the code:

 void CheckSetMenuInScreenSpace()
     {
 //min is left bottom of screen, max upper right corner
         var screenMin = new Vector2(0, 0);
         var screenMax = (Vector2)new Vector3(Screen.width, Screen.height, 0);
  
 //tried with this, didn't work
         Vector3[] corners = new Vector3[4];
         bubbleRect.GetWorldCorners(corners);
 //calculating boundaries (bottom left and top right) of the bubble RectTransform. not sure if I used pivot correctly in the formula
         var bubbleRectMin = new Vector2(bubbleRect.transform.position.x - (bubbleRect.rect.width * bubbleRect.pivot.x), bubbleRect.transform.position.y - (bubbleRect.rect.height * bubbleRect.pivot.y));
         var bubbleRectMax = new Vector2(bubbleRect.transform.position.x + (bubbleRect.rect.width * bubbleRect.pivot.x), bubbleRect.transform.position.y + (bubbleRect.rect.height * bubbleRect.pivot.y));
  
         if (bubbleRectMin.x < screenMin.x)
         {
             parentRect.anchoredPosition = new Vector2(screenMin.x + (bubbleRect.rect.width / 2), parentRect.anchoredPosition.y);
  
             var a = parentRect.rect.position;
         }
         else if (bubbleRectMax.x > screenMax.x)
         {
             parentRect.anchoredPosition = new Vector2(screenMax.x - (bubbleRect.rect.width / 2), parentRect.anchoredPosition.y);
         }
  
         if (bubbleRectMin.y < screenMin.y)
         {
             parentRect.anchoredPosition = new Vector2(parentRect.anchoredPosition.x, screenMin.y + (bubbleRect.rect.height / 2));
         }
         else if (bubbleRectMax.y > screenMax.y)
         {
             parentRect.anchoredPosition = new Vector2(parentRect.anchoredPosition.x, screenMax.y - (bubbleRect.rect.height / 2));
         }
     }

I think my problem is misunderstanding screen space, transform.position and anchored position.

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