FM/Assets/Scripts/Runtime/Test/ImageConverter.cs

using UnityEngine;
using System.IO;
using BitMiracle.LibTiff.Classic;

public class ImageConverter : MonoBehaviour
{
    public string pngPath;
    public string tiffPath;

    [ContextMenu("PngToTiff")]
    void PNG()
    {
        PngToTiff(pngPath, tiffPath);
    }

    [ContextMenu("TiffToPng")]
    void TIFF()
    {
        TiffToPng(tiffPath, pngPath);
    }

    // 检查纹理是否包含透明通道
    private static bool HasTransparency(Texture2D tex)
    {
        Color32[] pixels = tex.GetPixels32();
        for (int i = 0; i < pixels.Length; i++)
        {
            if (pixels[i].a < 255)
                return true;
        }
        return false;
    }

// PNG 转 TIFF (完整支持透明通道)
    public static void PngToTiff(string pngPath, string tiffPath, int compression = 5)
    {
        // 加载PNG文件
        byte[] pngBytes = File.ReadAllBytes(pngPath);
        Texture2D sourceTex = new Texture2D(2, 2, TextureFormat.RGBA32, false);
        sourceTex.LoadImage(pngBytes);
        
        // 检查是否包含透明通道
        bool hasAlpha = HasTransparency(sourceTex);
        int channels = hasAlpha ? 4 : 3;
        
        // 准备TIFF图像数据
        byte[] tiffData = new byte[sourceTex.width * sourceTex.height * channels];
        int pixelIndex = 0;
        
        // 垂直翻转并处理像素数据（Unity是左下原点，TIFF是左上原点）
        for (int y = sourceTex.height - 1; y >= 0; y--)
        {
            for (int x = 0; x < sourceTex.width; x++)
            {
                Color32 pixel = sourceTex.GetPixel(x, y);
                
                tiffData[pixelIndex++] = pixel.r;
                tiffData[pixelIndex++] = pixel.g;
                tiffData[pixelIndex++] = pixel.b;
                
                if (hasAlpha)
                {
                    tiffData[pixelIndex++] = pixel.a;
                }
            }
        }

        // 创建TIFF文件
        using (Tiff tiff = Tiff.Open(tiffPath, "w"))
        {
            // 设置基本参数
            tiff.SetField(TiffTag.IMAGEWIDTH, sourceTex.width);
            tiff.SetField(TiffTag.IMAGELENGTH, sourceTex.height);
            tiff.SetField(TiffTag.SAMPLESPERPIXEL, channels);
            tiff.SetField(TiffTag.BITSPERSAMPLE, 8);
            tiff.SetField(TiffTag.ROWSPERSTRIP, sourceTex.height);
            tiff.SetField(TiffTag.ORIENTATION, Orientation.TOPLEFT);
            tiff.SetField(TiffTag.PLANARCONFIG, PlanarConfig.CONTIG);
            
            // 设置光度解释（RGB或带Alpha的RGB）
            tiff.SetField(TiffTag.PHOTOMETRIC, hasAlpha ? Photometric.RGB : Photometric.MINISBLACK);
            
            // 设置Alpha通道信息
            if (hasAlpha)
            {
                ushort[] extrasamples = { (ushort)ExtraSample.UNASSALPHA };
                tiff.SetField(TiffTag.EXTRASAMPLES, extrasamples.Length, extrasamples);
            }
            
            // 设置压缩
            if (compression > 0)
            {
                tiff.SetField(TiffTag.COMPRESSION, Compression.ADOBE_DEFLATE);
                tiff.SetField(TiffTag.ZIPQUALITY, compression);
            }
            else
            {
                tiff.SetField(TiffTag.COMPRESSION, Compression.NONE);
            }
            
            // 写入图像数据
            tiff.WriteEncodedStrip(0, tiffData, tiffData.Length);
        }
    }

    // TIFF 转 PNG (支持透明通道)
    public static void TiffToPng(string tiffPath, string pngPath, bool preserveAlpha = true)
    {
        using (Tiff tiff = Tiff.Open(tiffPath, "r"))
        {
            int width = tiff.GetField(TiffTag.IMAGEWIDTH)[0].ToInt();
            int height = tiff.GetField(TiffTag.IMAGELENGTH)[0].ToInt();
            int channels = tiff.GetField(TiffTag.SAMPLESPERPIXEL)[0].ToInt();

            // 检查是否有额外通道（如Alpha）
            FieldValue[] extraSamples = tiff.GetField(TiffTag.EXTRASAMPLES);
            bool hasAlpha = extraSamples != null && extraSamples.Length > 0 &&
                            extraSamples[0].ToInt() == (int)ExtraSample.UNASSALPHA;

            // 读取图像数据
            byte[] buffer = new byte[width * height * channels];
            for (int i = 0; i < height; i++)
            {
                tiff.ReadScanline(buffer, i * width * channels, i, 0);
            }

            // 创建Texture2D
            TextureFormat format = preserveAlpha && (channels == 4 || hasAlpha)
                ? TextureFormat.RGBA32
                : TextureFormat.RGB24;

            Texture2D tex = new Texture2D(width, height, format, false);

            // 填充像素 (垂直翻转)
            Color32[] colors = new Color32[width * height];
            for (int y = 0; y < height; y++)
            {
                int flippedY = height - 1 - y;
                for (int x = 0; x < width; x++)
                {
                    int bufferIndex = (y * width + x) * channels;
                    int colorIndex = flippedY * width + x;

                    byte r = buffer[bufferIndex];
                    byte g = buffer[bufferIndex + 1];
                    byte b = buffer[bufferIndex + 2];
                    byte a = (byte)255;

                    // 处理Alpha通道
                    if (preserveAlpha && (channels == 4 || hasAlpha))
                    {
                        a = channels == 4 ? buffer[bufferIndex + 3] : (hasAlpha ? buffer[bufferIndex + 3] : (byte)255);
                    }

                    colors[colorIndex] = new Color32(r, g, b, a);
                }
            }

            tex.SetPixels32(colors);
            tex.Apply();

            // 保存为PNG
            File.WriteAllBytes(pngPath, tex.EncodeToPNG());
        }
    }
}