unity 文件夹图片导入修改方法

using System.IO;
using System.Reflection;
using UnityEditor;
using UnityEngine;
using UnityEngine.UI;

[CustomEditor(typeof(TextureImporter))]

public class ImageImport : AssetPostprocessor
{
    //--导入贴图前
    public void OnPreprocessTexture()
    {
        TextureImporter importer = assetImporter as TextureImporter;
        ChangeTextureImportFormat(importer, assetPath);
    }

    static int[] formatSize = new int[] { 32, 64, 128, 256, 512, 1024, 2048, 4096 };
    static int FitSize(int picValue)
    {
        foreach (var one in formatSize)
        {
            if (picValue <= one)
            {
                return one;
            }
        }

        return 1024;
    }

    //贴图不存在、meta文件不存在、图片尺寸发生修改需要重新导入
    static bool IsFirstImport(TextureImporter importer, string assetPath)
    {
        (int width, int height) = GetTextureImporterSize(importer);
        Texture tex = AssetDatabase.LoadAssetAtPath<Texture2D>(assetPath);
        bool hasMeta = File.Exists(AssetDatabase.GetAssetPathFromTextMetaFilePath(assetPath));
        return tex == null || !hasMeta || (tex.width != width && tex.height != height);
    }

    //获取导入图片的宽高
    static (int, int) GetTextureImporterSize(TextureImporter importer)
    {
        if (importer != null)
        {
            object[] args = new object[2];
            MethodInfo mi = typeof(TextureImporter).GetMethod("GetWidthAndHeight", BindingFlags.NonPublic | BindingFlags.Instance);
            mi.Invoke(importer, args);
            return ((int)args[0], (int)args[1]);
        }
        return (0, 0);
    }
    static Object targetObj;
    //[MenuItem("Tools/TextureEdit")]
    static void EditTexture()
    {

        Object[] objs = Selection.GetFiltered(typeof(Texture), SelectionMode.DeepAssets);
        foreach (Object obj in objs)
        {
            string path = AssetDatabase.GetAssetPath(obj);
            if (obj.GetType() == typeof(Texture2D) && path.Contains(".png") == true)
            {
                TextureImporter texture = AssetImporter.GetAtPath(path) as TextureImporter;
                ChangeTextureImportFormat(texture, path);
                AssetDatabase.ImportAsset(path);
            }
        }
    }


    public static void ChangeTextureImportFormat(TextureImporter importer, string assetPath)
    {
        //try
        //{
        //    if (importer != null && !assetPath.EndsWith("_Normal.png") && !assetPath.EndsWith("_Normal.bmp") && !assetPath.EndsWith("_Normal.tga"))
        //    {
        //        //if (IsFirstImport(importer, assetPath))
        //        //{
        //        importer.textureType = TextureImporterType.Sprite;
        //        importer.spritePixelsPerUnit = 1;
        //        importer.spriteImportMode = SpriteImportMode.Single;

        //        int textureSize = Mathf.Max(4096, 4096);
        //        int SizeType = FitSize(textureSize);
        //        ////Standalone
        //        TextureImporterPlatformSettings settings = importer.GetPlatformTextureSettings("Standalone");
        //        settings.overridden = true;
        //        settings.maxTextureSize = SizeType;

        //        settings.format = importer.DoesSourceTextureHaveAlpha() ? TextureImporterFormat.DXT5 : TextureImporterFormat.DXT5Crunched;


        //        importer.SetPlatformTextureSettings(settings);


        //        settings = importer.GetPlatformTextureSettings("iPhone");
        //        settings.overridden = true;
        //        settings.maxTextureSize = SizeType;
        //        settings.format = importer.DoesSourceTextureHaveAlpha() ? TextureImporterFormat.ASTC_4x4 : TextureImporterFormat.ASTC_6x6;
        //        importer.SetPlatformTextureSettings(settings);

        //        settings = importer.GetPlatformTextureSettings("Android");
        //        importer.spritePixelsPerUnit = 1;
        //        settings.overridden = true;
        //        settings.maxTextureSize = SizeType;
        //        settings.format = importer.DoesSourceTextureHaveAlpha() ? TextureImporterFormat.ASTC_4x4 : TextureImporterFormat.ASTC_6x6;
        //        importer.SetPlatformTextureSettings(settings);
        //        //}
        //    }
        //}
        //catch (System.Exception e)
        //{

        //}
    }
}