/// <summary>

/// 圖像縮略圖處理

/// </summary>

/// <param name="bytes">圖像源數據</param>

/// <param name="compression">壓縮質量 1-100</param>

/// <param name="thumbWidth">縮略圖的寬</param>

/// <param name="thumbHeight">縮略圖的高</param>

/// <returns></returns>

public static byte[] ConvertToThumbnail(byte[] bytes, int compression = 100, int thumbWidth = 0, int thumbHeight = 0)

{

byte[] bs = null;

try

{

if (bytes != null)

{

using (MemoryStream ms = new MemoryStream(bytes))

{

using (Bitmap srcimg = new Bitmap(ms))

{

if (thumbWidth == 0 && thumbHeight == 0)

{

thumbWidth = srcimg.Width;

thumbHeight = srcimg.Height;

}

using (Bitmap dstimg = new Bitmap(thumbWidth, thumbHeight))//圖片壓縮質量

{

//從Bitmap創(chuàng)建一個System.Drawing.Graphics對象，用來繪制高質量的縮小圖。

using (Graphics gr = Graphics.FromImage(dstimg))

{

//把原始圖像繪制成上面所設置寬高的縮小圖

Rectangle rectDestination = new Rectangle(0, 0, thumbWidth, thumbHeight);

gr.Clear(Color.WhiteSmoke);

gr.CompositingQuality = CompositingQuality.HighQuality;

gr.SmoothingMode = SmoothingMode.HighQuality;

gr.InterpolationMode = InterpolationMode.HighQualityBicubic;

gr.DrawImage(srcimg, rectDestination, 0, 0, srcimg.Width, srcimg.Height, GraphicsUnit.Pixel);

EncoderParameters ep = new EncoderParameters(1);

ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, compression);//設置壓縮的比例1-100

ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();

ImageCodecInfo jpegICIinfo = arrayICI.FirstOrDefault(t => t.FormatID == System.Drawing.Imaging.ImageFormat.Png.Guid);

using (MemoryStream dstms = new MemoryStream())

{

if (jpegICIinfo != null)

{

dstimg.Save(dstms, jpegICIinfo, ep);

}

else

{

dstimg.Save(dstms, System.Drawing.Imaging.ImageFormat.Png);//保存到內存里

}

bs = new Byte[dstms.Length];

dstms.Position = 0;

dstms.Read(bs, 0, bs.Length);

}

}

}

}

}

}

}

catch (Exception ex)

{

LogManager.DefaultLogger.Error(LogConvert.ParseWebEx(ex), string.Concat("ConvertToThumbnail error.", thumbWidth, " ", thumbHeight));

}

return bs;

}

總結

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