https://docs.microsoft.com/zh-cn/dotnet/api/system.drawing.imaging.encoder.quality?view=netframework-4.8
public ActionResult SaveVideoThumbnailFile(string keyValue,string strEntity)
{
Encoder myEncoder;
EncoderParameter myEncoderParameter;
EncoderParameters myEncoderParameters;
ImageCodecInfo myImageCodecInfo;
myEncoder = Encoder.Quality;
myEncoderParameters = new EncoderParameters(1);
myEncoderParameter = new EncoderParameter(myEncoder, 100L);
myEncoderParameters.Param[0] = myEncoderParameter;
//int width= int height, int offsetX, int offsetY
var PostData = strEntity.ToJObject();
int width = (int)PostData["width"];
int height = (int)PostData["height"];
int offsetX = (int)PostData["offsetX"];
int offsetY = (int)PostData["offsetY"];
string filePath = "/Resource/VideoThumbnailFile/" + keyValue;
//创建路径
string firstfile = System.Web.HttpContext.Current.Server.MapPath("~" + ModelList[0].VideoUrl);
myImageCodecInfo = GetEncoderInfo(MimeMapping.GetMimeMapping(firstfile));
yfile = System.Web.HttpContext.Current.Server.MapPath("~" + model.VideoUrl);
file = yfile.Replace("VideoFile", "VideoThumbnailFile");
Bitmap refile = GetPartOfImageRec(yfile, width, height, offsetX, offsetY);
refile.Save(file,myImageCodecInfo, myEncoderParameters);
}
/// <summary>
/// 截取一张图片的指定部分
/// </summary>
/// <param name="bitmapPathAndName">原始图片路径名称</param>
/// <param name="width">截取图片的宽度</param>
/// <param name="height">截取图片的高度</param>
/// <param name="offsetX">开始截取图片的X坐标</param>
/// <param name="offsetY">开始截取图片的Y坐标</param>
/// <returns></returns>
public Bitmap GetPartOfImageRec(string bitmapPathAndName, int width, int height, int offsetX, int offsetY)
{
Bitmap sourceBitmap = new Bitmap(bitmapPathAndName);
Bitmap resultBitmap = new Bitmap(width, height);
using (Graphics g = Graphics.FromImage(resultBitmap))
{
Rectangle resultRectangle = new Rectangle(0, 0, width, height);
Rectangle sourceRectangle = new Rectangle(0 + offsetX, 0 + offsetY, width, height);
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.White);
g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);
}
return resultBitmap;
}
/// <summary>
/// 截取一张图片的指定部分
/// </summary>
/// <param name="bitmapPathAndName">原始图片路径名称</param>
/// <param name="width">截取图片的宽度</param>
/// <param name="height">截取图片的高度</param>
/// <param name="offsetX">开始截取图片的X坐标</param>
/// <param name="offsetY">开始截取图片的Y坐标</param>
/// <returns></returns>
public Bitmap GetPartOfImageRec(string bitmapPathAndName, int width, int height, int offsetX, int offsetY)
{
Bitmap sourceBitmap = new Bitmap(bitmapPathAndName);
Bitmap resultBitmap = new Bitmap(width, height);
using (Graphics g = Graphics.FromImage(resultBitmap))
{
Rectangle resultRectangle = new Rectangle(0, 0, width, height);
Rectangle sourceRectangle = new Rectangle(0 + offsetX, 0 + offsetY, width, height);
g.InterpolationMode =System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
g.SmoothingMode =System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.Clear(Color.White);
g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);
}
return resultBitmap;
}