FM/Assets/Scripts/FUJIFILM/UI/ImageScaler.cs

using UnityEngine;
using UnityEngine.UI;

namespace HK.FUJIFILM
{
    public static class RawImageScaler
    {
        /// <summary>
        /// 将Texture2D赋值给RawImage并确保等比缩放，保持在RawImage最大范围内
        /// </summary>
        /// <param name="rawImage">目标RawImage组件</param>
        /// <param name="texture">要显示的Texture2D</param>
        /// <param name="maxWidth">最大宽度限制（若为0则使用RawImage的当前宽度）</param>
        /// <param name="maxHeight">最大高度限制（若为0则使用RawImage的当前高度）</param>
        public static void SetTextureWithAspectRatio(RawImage rawImage, Texture2D texture, float maxWidth = 0,
            float maxHeight = 0)
        {
            if (rawImage == null || texture == null)
            {
                Debug.LogError("RawImage或Texture2D不能为空");
                return;
            }

            // 赋值纹理
            rawImage.texture = texture;

            // 获取纹理原始宽高
            float textureWidth = texture.width;
            float textureHeight = texture.height;

            // 如果未指定最大宽高，使用RawImage当前的尺寸作为限制
            float limitWidth = maxWidth > 0 ? maxWidth : rawImage.rectTransform.rect.width;
            float limitHeight = maxHeight > 0 ? maxHeight : rawImage.rectTransform.rect.height;

            // 计算宽高比例
            float textureAspect = textureWidth / textureHeight;
            float limitAspect = limitWidth / limitHeight;

            // 计算缩放后的尺寸（保持比例并适应限制范围）
            float scaledWidth, scaledHeight;

            if (textureAspect > limitAspect)
            {
                // 纹理更宽，按宽度限制缩放
                scaledWidth = limitWidth;
                scaledHeight = scaledWidth / textureAspect;
            }
            else
            {
                // 纹理更高或比例相同，按高度限制缩放
                scaledHeight = limitHeight;
                scaledWidth = scaledHeight * textureAspect;
            }

            // 应用缩放后的尺寸
            rawImage.rectTransform.sizeDelta = new Vector2(scaledWidth, scaledHeight);

            // 可选：居中显示
            rawImage.rectTransform.anchorMin = new Vector2(0.5f, 0.5f);
            rawImage.rectTransform.anchorMax = new Vector2(0.5f, 0.5f);
            rawImage.rectTransform.pivot = new Vector2(0.5f, 0.5f);
            rawImage.rectTransform.anchoredPosition = Vector2.zero;
        }
    }

    public static class ImageScaler
    {
        /// <summary>
        /// 将Image等比缩放到不超过指定的最大尺寸（宽和高中较大的值不超过maxSize）
        /// </summary>
        /// <param name="image">需要缩放的Image组件</param>
        /// <param name="maxSize">宽和高中较大值的最大限制</param>
        /// <param name="keepOriginalIfSmaller">如果原图比限制小，是否保持原图大小</param>
        public static void ScaleImageWithSize(Image image, float maxSize, bool keepOriginalIfSmaller = false)
        {
            if (image == null)
            {
                Debug.LogError("Image组件不能为空！");
                return;
            }

            // 获取原始尺寸
            float originalWidth, originalHeight;

            if (image.sprite != null)
            {
                // 使用Sprite的原始尺寸
                originalWidth = image.sprite.rect.width;
                originalHeight = image.sprite.rect.height;
            }
            else
            {
                // 没有Sprite时使用当前RectTransform的尺寸
                originalWidth = image.rectTransform.rect.width;
                originalHeight = image.rectTransform.rect.height;
            }

            // 计算缩放比例
            float scaleRatio = CalculateScaleRatio(originalWidth, originalHeight, maxSize, keepOriginalIfSmaller);

            // 应用缩放后的尺寸
            image.rectTransform.sizeDelta = new Vector2(
                originalWidth,
                originalHeight
            );
            // image.rectTransform.sizeDelta = new Vector2(
            //     originalWidth * scaleRatio,
            //     originalHeight * scaleRatio
            // );
        }

        public static void ScaleImageWithMaxSize(Image image, float maxSize, bool keepOriginalIfSmaller = false)
        {
            if (image == null)
            {
                Debug.LogError("Image组件不能为空！");
                return;
            }

            // 获取原始尺寸
            float originalWidth, originalHeight;

            if (image.sprite != null)
            {
                // 使用Sprite的原始尺寸
                originalWidth = image.sprite.rect.width;
                originalHeight = image.sprite.rect.height;
            }
            else
            {
                // 没有Sprite时使用当前RectTransform的尺寸
                originalWidth = image.rectTransform.rect.width;
                originalHeight = image.rectTransform.rect.height;
            }

            // 计算缩放比例
            float scaleRatio = CalculateScaleRatio(originalWidth, originalHeight, maxSize, keepOriginalIfSmaller);

            // 应用缩放后的尺寸
            image.rectTransform.sizeDelta = new Vector2(
                originalWidth * scaleRatio,
                originalHeight * scaleRatio
            );
        }

        /// <summary>
        /// 计算缩放比例
        /// </summary>
        private static float CalculateScaleRatio(float originalWidth, float originalHeight, float maxSize,
            bool keepOriginalIfSmaller)
        {
            // 找到原始宽高中的较大值
            float maxOriginal = Mathf.Max(originalWidth, originalHeight);

            // 如果原图的最大边小于等于限制值，且需要保持原图大小，则不缩放
            if (maxOriginal <= maxSize && keepOriginalIfSmaller)
            {
                return 1f; // 不缩放
            }

            // 计算缩放比例（让最大边刚好等于maxSize）
            return maxSize / maxOriginal;
        }
    }
}