c# bitmap压缩导致png不透明的问题解决

新建.net 6控制台项目
安装System.Drawing.Common包
在这里插入图片描述
代码如下

using System.Drawing;
using System.Drawing.Imaging;

namespace PngCompress02
{
    internal class Program
    {
        static void Main(string[] args)
        {
            CompressPngImage(@"E:\Desktop\6.png", @"E:\Desktop\6_60.png", 60);
            Console.WriteLine("完成");
        }

        public static void CompressPngImage(string sourcePath, string targetPath, long quality)
        {
            using (var image = Image.FromFile(sourcePath))
            {
                var encoderParameters = new EncoderParameters(1);
                encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);

                var imageCodecInfo = GetPngImageCodec();
                //var imageFormat = ImageFormat.Png;
                Bitmap bitmap = new Bitmap(image);
                bitmap.Save(targetPath, imageCodecInfo, encoderParameters);
            }
        }

        private static ImageCodecInfo GetPngImageCodec()
        {
            var codecs = ImageCodecInfo.GetImageEncoders();
            foreach (var codec in codecs)
            {
                if (codec.FormatID == ImageFormat.Png.Guid)
                {
                    return codec;
                }
            }
            throw new ArgumentException("No PNG image codec found.");
        }
    }
}