using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

namespace BITKit.UX
{

	/// <summary>
	/// Created by Vitens on 2020/12/11 20:48:35
	/// 
	/// Description : 
	///      全屏背景图片等比例拉伸自适应
	/// </summary>
	[ExecuteInEditMode]
	public class UGUIBackgroundImageScaler : MonoBehaviour
	{
		//图片原大小(压缩前的)
		[SerializeField] private Vector2 textureOriginSize = new Vector2(2048, 1024);

		// Start is called before the first frame update
		private void Start()
		{
			Scaler();
		}

		//适配
		private void Scaler()
		{
			//当前画布尺寸
			Vector2 canvasSize = gameObject.GetComponentInParent<Canvas>().GetComponent<RectTransform>().sizeDelta;
			//当前画布尺寸长宽比
			float screenxyRate = canvasSize.x / canvasSize.y;

			//图片尺寸 这个得到的结果是 (0,0) ?
			//Vector2 bgSize = bg.mainTexture.texelSize;
			Vector2 bgSize = textureOriginSize;
			//视频尺寸长宽比
			float texturexyRate = bgSize.x / bgSize.y;

			RectTransform rt = (RectTransform)transform;
			//视频x偏长,需要适配y（下面的判断 '>' 改为 '<' 就是视频播放器的视频方式）
			if (texturexyRate > screenxyRate)
			{
				int newSizeY = Mathf.CeilToInt(canvasSize.y);
				int newSizeX = Mathf.CeilToInt((float)newSizeY / bgSize.y * bgSize.x);
				rt.sizeDelta = new Vector2(newSizeX, newSizeY);
			}
			else
			{
				int newVideoSizeX = Mathf.CeilToInt(canvasSize.x);
				int newVideoSizeY = Mathf.CeilToInt((float)newVideoSizeX / bgSize.x * bgSize.y);
				rt.sizeDelta = new Vector2(newVideoSizeX, newVideoSizeY);
			}
		}

		private void Update()
		{
#if UNITY_EDITOR
			//editor模式下测试用
			Scaler();
#endif
		}

	}
}