C# “参数无效。” 使用保存位图时
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"Parameter is not valid." when using saving bitmap
提问by CruelIO
Im trying to save a bitmap jpg format with a specified encoding quality. However im getting an exception ("Parameter is not valid.") when calling the save method.
我试图用指定的编码质量保存位图 jpg 格式。但是我在调用 save 方法时遇到异常（“参数无效。”）。
If i leave out the two last parameters in the bmp.save it works fine.
如果我在 bmp.save 中省略了最后两个参数，它工作正常。
EncoderParameters eps = new EncoderParameters(1);
eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 16);
ImageCodecInfo ici = GetEncoderInfo("image/jpeg");
string outfile = outputpath + "\" + fileaddition + sourcefile.Name;
bmp.Save(outfile,ici,eps );
bmp.Dispose();
image.Dispose();
return true;
}
ImageCodecInfo GetEncoderInfo(string mimeType)
{
int j;
ImageCodecInfo[] encoders;
encoders = ImageCodecInfo.GetImageEncoders();
for (j = 0; j < encoders.Length; ++j)
{
if (encoders[j].MimeType == mimeType)
return encoders[j];
}
return null;
}
}
Thank you
谢谢
采纳答案by Hans Passant
GDI+ is pretty flaky. You'll need to use 16L for the value or cast to (long).
GDI+ 非常脆弱。您需要使用 16L 作为值或转换为（长）。
回答by Mahdi
You should cast quality value to long, like this:
您应该将质量值转换为 long，如下所示：
eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)16);
