/// <summary>
/// 按比例缩放图片
/// </summary>
/// <param name="source"></param>
/// <param name="target"></param>
/// <param name="destHeight"></param>
/// <param name="destWidth"></param>
/// <returns></returns>
public static bool GetThumbnail(string source, string target, int destWidth = 1024, int destHeight = 800)
{
try
{
if (!File.Exists(source))
{
return(false);
}
System.Drawing.Image imgSource = Image.FromFile(source);
System.Drawing.Imaging.ImageFormat thisFormat = imgSource.RawFormat;
int sW = 0, sH = 0;
// 按比例缩放
int sWidth = imgSource.Width;
int sHeight = imgSource.Height;
if (sHeight > destHeight || sWidth > destWidth)
{
if ((sWidth * destHeight) > (sHeight * destWidth))
{
sW = destWidth;
sH = (destWidth * sHeight) / sWidth;
}
else
{
sH = destHeight;
sW = (sWidth * destHeight) / sHeight;
}
}
else
{
sW = sWidth;
sH = sHeight;
}
Bitmap outBmp = new Bitmap(destWidth, destHeight);
Graphics g = Graphics.FromImage(outBmp);
g.Clear(Color.Transparent);
// 设置画布的描绘质量
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(imgSource, new Rectangle((destWidth - sW) / 2, (destHeight - sH) / 2, sW, sH), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel);
g.Dispose();
// 以下代码为保存图片时，设置压缩质量
ImageCodecInfo myImageCodecInfo = GetEncoderInfo(FileContentType.GetMimeMapping(source));
EncoderParameters encoderParams = new EncoderParameters();
long[] quality = new long[1];
quality[0] = 100;
EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
encoderParams.Param[0] = encoderParam;
imgSource.Dispose();
EncoderParameters myEncoderParameters = new EncoderParameters(1);
myEncoderParameters.Param[0] = encoderParam;
outBmp.Save(target, myImageCodecInfo, myEncoderParameters);
return(true);
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// 压缩文件
/// </summary>
/// <param name="srcFile"></param>
/// <param name="destFile"></param>
/// <param name="level"></param>
public static void Compress(string srcFile, string destFile, long level)
{
Bitmap srcBitMap = new Bitmap(srcFile);
Stream s = new FileStream(destFile, FileMode.Create);
Compress(srcBitMap, s, level, FileContentType.GetMimeMapping(srcFile));
s.Close();
}
/// <summary>
/// 图片压缩到字节数组
/// </summary>
/// <param name="srcFile"></param>
/// <param name="level">0-100</param>
/// <returns></returns>
public static byte[] CompressToBytes(string srcFile, long level)
{
byte[] bs = null;
Bitmap srcBitMap = new Bitmap(srcFile);
System.IO.MemoryStream ms = new MemoryStream();
Compress(srcBitMap, ms, level, FileContentType.GetMimeMapping(srcFile));
bs = ms.ToArray();
ms.Close();
return(bs);
}