c# - 使用 .Net Framework 4.5 压缩图像

Question

我有下一个代码:

class Program
{
    const string ImagePath = @"C:\mypath\36";
    private const int Quality = 50;

    static void Main()
    {
        Console.WriteLine("Inicio: " + DateTime.Now);    
        var images = Directory.GetFiles(ImagePath);

        foreach (var name in images)
        {
            var bitmap = new Bitmap(name);
            var tname = name.Split('\\')[5].Split('.')[0];
            VariousQuality(bitmap, tname);
        }
        Console.WriteLine("Finalizacion: " + DateTime.Now);
        Console.ReadLine();
    }

    static void VariousQuality(Image original, string name)
    {
        var codecs = ImageCodecInfo.GetImageEncoders();
        var jpgEncoder = codecs.FirstOrDefault(codec => codec.FormatID == ImageFormat.Jpeg.Guid);

        if (jpgEncoder == null) return;

        var encoder = Encoder.Quality;
        var encoderParameters = new EncoderParameters(1);

        var encoderParameter = new EncoderParameter(encoder, Quality);
        encoderParameters.Param[0] = encoderParameter;

        var fileOut = Path.Combine(ImagePath, "__" + name + ".jpg");
        var ms = new FileStream(fileOut, FileMode.Create, FileAccess.Write);
        original.Save(ms, jpgEncoder, encoderParameters);

        ms.Flush();
        ms.Close();

    }

    static void DefaultCompressionPng(Image original)
    {
        var ms = new MemoryStream();
        original.Save(ms, ImageFormat.Png);
        var compressed = new Bitmap(ms);
        ms.Close();

        var fileOutPng = Path.Combine(ImagePath, "default.png");
        compressed.Save(fileOutPng, ImageFormat.Png);
    }

    static void DefaultCompressionJpeg(Image original)
    {
        var ms = new MemoryStream();
        original.Save(ms, ImageFormat.Jpeg);
        var compressed = new Bitmap(ms);
        ms.Close();

        var fileOutPng = Path.Combine(ImagePath, "default.jpg");
        compressed.Save(fileOutPng, ImageFormat.Jpeg);
    }

}

该代码适用于 .Net 4.0 版，但现在我将代码更新到 4.5 版，我收到下一个错误:

original.Save(ms, jpgEncoder, encoderParameters);

An unhandled exception of type 'System.ArgumentException' occurred in System.Drawing.dll {System.Collections.ListDictionaryInternal} The parameter is invalid. System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams)
ImageCompression.Program.VariousQuality(Image original, String name 2012\Projects\ImageCompression\ImageCompression\Program.cs:line 44

关于如何修复此错误的一些想法？

Answer 1

将 Quality 类型更改为 long。

private const long Quality = 50;

附言

MSDN Encoder.Quality示例:

 myEncoderParameter = new EncoderParameter(myEncoder, 50L);