C#图片无损压缩
//引用命名空间
using System.Drawing.Imaging;
using System.Drawing;
using System.Drawing.Drawing2D;
#region GetPicThumbnail
/// <summary>
/// 无损压缩图片
/// </summary>
/// <param name="sFile">原图片</param>
/// <param name="dFile">压缩后保存位置</param>
/// <param name="dHeight">高度</param>
/// <param name="dWidth"></param>
/// <param name="flag">压缩质量 1-100</param>
/// <returns></returns>
public
bool
GetPicThumbnail(
string
sFile,
string
dFile,
int
dHeight,
int
dWidth,
int
flag)
{
System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
ImageFormat tFormat = iSource.RawFormat;
int
sW = 0, sH = 0;
//按比例缩放
Size tem_size =
new
Size(iSource.Width, iSource.Height);
if
(tem_size.Width > dHeight || tem_size.Width > dWidth)
//将**改成c#中的或者操作符号
{
if
((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
{
sW = dWidth;
sH = (dWidth * tem_size.Height) / tem_size.Width;
}
else
{
sH = dHeight;
sW = (tem_size.Width * dHeight) / tem_size.Height;
}
}
else
{
sW = tem_size.Width;
sH = tem_size.Height;
}
Bitmap ob =
new
Bitmap(dWidth, dHeight);
Graphics g = Graphics.FromImage(ob);
g.Clear(Color.WhiteSmoke);
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(iSource,
new
Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
g.Dispose();
//以下代码为保存图片时，设置压缩质量
EncoderParameters ep =
new
EncoderParameters();
long
[] qy =
new
long
[1];
qy[0] = flag;
//设置压缩的比例1-100
EncoderParameter eParam =
new
EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
ep.Param[0] = eParam;
try
{
ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
ImageCodecInfo jpegICIinfo =
null
;
for
(
int
x = 0; x < arrayICI.Length; x++)
{
if
(arrayICI[x].FormatDescription.Equals(
"JPEG"
))
{
jpegICIinfo = arrayICI[x];
break
;
}
}
if
(jpegICIinfo !=
null
)
{
ob.Save(dFile, jpegICIinfo, ep);
//dFile是压缩后的新路径
}
else
{
ob.Save(dFile, tFormat);
}
return
true
;
}
catch
{
return
false
;
}
finally
{
iSource.Dispose();
ob.Dispose();
}
}
#endregion
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