代码:
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private static ImageCodecInfo GetImageCodecInfo(ImageFormat imageFormat) { ImageCodecInfo[] imageCodecInfoArr = ImageCodecInfo.GetImageDecoders(); foreach (ImageCodecInfo imageCodecInfo in imageCodecInfoArr) { if (imageCodecInfo.FormatID == imageFormat.Guid) { return imageCodecInfo; } } return null; }
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
MemoryStream ms = HttpUtil.HttpDownloadFile(url); Bitmap bmp = new Bitmap(ms); EncoderParameters encoderParameters = new EncoderParameters(1); EncoderParameter encoderParameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 75L); encoderParameters.Param[0] = encoderParameter; MemoryStream msCompress = new MemoryStream(); bmp.Save(msCompress, GetImageCodecInfo(ImageFormat.Jpeg), encoderParameters); Bitmap bmpCompress = new Bitmap(msCompress); bmpCompress.Save(path); bmp.Save(path2); msCompress.Close(); ms.Close();
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
using System; using System.Collections.Generic; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; using System.IO; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SunCreate.Common.ComLib { /// <summary> /// 图片缩放 /// </summary> public class ZoomImageUtil { #region 图片缩放 /// <summary> /// 图片缩放 /// </summary> /// <param name="bArr">图片字节流</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> public static byte[] GetThumbnail(byte[] bArr, int width, int height) { if (bArr == null) return null; MemoryStream ms = new MemoryStream(bArr); Bitmap bmp = (Bitmap)Image.FromStream(ms); ms.Close(); bmp = GetThumbnail(bmp, width, height); ImageCodecInfo imageCodecInfo = GetEncoder(ImageFormat.Jpeg); EncoderParameters encoderParameters = new EncoderParameters(1); EncoderParameter encoderParameter = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 75L); encoderParameters.Param[0] = encoderParameter; ms = new MemoryStream(); bmp.Save(ms, imageCodecInfo, encoderParameters); byte[] result = ms.ToArray(); ms.Close(); bmp.Dispose(); return result; } #endregion #region 图片缩放 /// <summary> /// 图片缩放 /// </summary> /// <param name="bmp">图片</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> private static Bitmap GetThumbnail(Bitmap bmp, int width, int height) { if (width == 0 && height == 0) { width = bmp.Width; height = bmp.Height; } else { if (width == 0) { width = height * bmp.Width / bmp.Height; } if (height == 0) { height = width * bmp.Height / bmp.Width; } } Image imgSource = bmp; Bitmap outBmp = new Bitmap(width, height); Graphics g = Graphics.FromImage(outBmp); g.Clear(Color.Transparent); // 设置画布的描绘质量 g.CompositingQuality = CompositingQuality.Default; g.SmoothingMode = SmoothingMode.Default; g.InterpolationMode = InterpolationMode.Default; g.DrawImage(imgSource, new Rectangle(0, 0, width, height + 1), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel); g.Dispose(); imgSource.Dispose(); bmp.Dispose(); return outBmp; } #endregion #region 椭圆形缩放 /// <summary> /// 椭圆形缩放 /// </summary> /// <param name="bArr">图片字节流</param> /// <param name="width">目标宽度,若为0,表示宽度按比例缩放</param> /// <param name="height">目标长度,若为0,表示长度按比例缩放</param> public static byte[] GetEllipseThumbnail(byte[] bArr, int width, int height) { if (bArr == null) return null; MemoryStream ms = new MemoryStream(bArr); Bitmap bmp = (Bitmap)Image.FromStream(ms); Bitmap newBmp = new Bitmap(width, height); using (Graphics g = Graphics.FromImage(newBmp)) { using (TextureBrush br = new TextureBrush(bmp)) { br.ScaleTransform(width / (float)bmp.Width, height / (float)bmp.Height); g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; g.FillEllipse(br, new Rectangle(Point.Empty, new Size(width, height))); } } MemoryStream newMs = new MemoryStream(); newBmp.Save(newMs, System.Drawing.Imaging.ImageFormat.Png); byte[] result = newMs.ToArray(); bmp.Dispose(); newBmp.Dispose(); ms.Close(); newMs.Dispose(); return result; } #endregion #region GetEncoder private static ImageCodecInfo GetEncoder(ImageFormat format) { ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders(); foreach (ImageCodecInfo codec in codecs) { if (codec.FormatID == format.Guid) { return codec; } } return null; } #endregion } }