Unity等比压缩图片

using System.IO;
using System.Threading.Tasks;
using UnityEngine;

/// <summary>压缩图片</summary>
public class ImageResizer 
{
    /// <summary>
    /// 压缩并保存图片
    /// </summary>
    /// <param name="inputPath">图片源</param>
    /// <param name="outputPath">修改后保存地址</param>
    /// <param name="maxResolution">最大高度</param>
    public void CompressAndSave(string inputPath, string outputPath,int maxResolution = 500)
    {
        Texture2D originalTexture = LoadTexture(inputPath);

        if (originalTexture != null)
        {
            // 压缩图片并保存到指定路径
            Texture2D compressedTexture = CompressTexture(originalTexture, maxResolution);
            SaveTexture(compressedTexture, outputPath);
        }
    }

    // 从文件加载纹理
    private Texture2D LoadTexture(string path)
    {
        Texture2D texture = null;

        try
        {
            byte[] fileData = File.ReadAllBytes(path);
            texture = new Texture2D(2, 2, TextureFormat.RGBA32, false);
            texture.LoadImage(fileData);
        }
        catch (IOException e)
        {
            Debug.LogError("Failed to load texture: " + e.Message);
        }

        return texture;
    }

    // 压缩纹理到目标大小
    private Texture2D CompressTexture(Texture2D texture, int targetWidth)
    {
        // 计算目标高度，保持宽高比不变
        int targetHeight = Mathf.RoundToInt((float)texture.height / texture.width * targetWidth);

        Texture2D compressedTexture = new Texture2D(targetWidth, targetHeight, TextureFormat.RGBA32, false);
        RenderTexture renderTexture = RenderTexture.GetTemporary(targetWidth, targetHeight);

        Graphics.Blit(texture, renderTexture);
        RenderTexture.active = renderTexture;
        compressedTexture.ReadPixels(new Rect(0, 0, targetWidth, targetHeight), 0, 0);

        RenderTexture.ReleaseTemporary(renderTexture);
        return compressedTexture;
    }

    // 将纹理保存为文件
    private void SaveTexture(Texture2D texture, string path)
    {
        byte[] bytes = texture.EncodeToPNG();
        File.WriteAllBytes(path, bytes);
    }
}