using UnityEngine;
using UnityEngine.UI;

static class CanvasExtension {
	public static Vector2 SizeToParent(this RawImage image, float padding = 0) {
		float w = 0, h = 0;
		var parent = image.transform.parent.GetComponent<RectTransform>();
		var imageTransform = image.GetComponent<RectTransform>();
 
		// check if there is something to do
		if (image.texture != null) {
			if (!parent) { return imageTransform.sizeDelta; } //if we don't have a parent, just return our current width;
			padding = 1 - padding;
			float ratio = image.texture.width / (float)image.texture.height;
			var bounds = new Rect(0, 0, parent.rect.width, parent.rect.height);
			if (Mathf.RoundToInt(imageTransform.eulerAngles.z) % 180 == 90) {
				//Invert the bounds if the image is rotated
				bounds.size = new Vector2(bounds.height, bounds.width);
			}
			//Size by height first
			h = bounds.height * padding;
			w = h * ratio;
			if (w < bounds.width * padding) { //If it doesn't fit, fallback to width;
				w = bounds.width * padding;
				h = w / ratio;
			}
		}
		imageTransform.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, w);
		imageTransform.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, h);
		return imageTransform.sizeDelta;
	}
}