在asp.net中,上传图片功能或者是常用的,生成缩略图也是常用的。baidu或者google,c#的方法也是很多的,但是一用却发现缩略图不清晰啊,缩略图片太大之类的事情,下面是我在处理图片上的代码,效果不错,所以拿出来分享,(效果能达到一些绘图软件的效果)
代码如下:
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/// asp.net上传图片并生成缩略图 |
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/// <param name="upImage">HtmlInputFile控件</param> |
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/// <param name="sSavePath">保存的路径,些为相对服务器路径的下的文件夹</param> |
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/// <param name="sThumbExtension">缩略图的thumb</param> |
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/// <param name="intThumbWidth">生成缩略图的宽度</param> |
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/// <param name="intThumbHeight">生成缩略图的高度</param> |
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/// <returns>缩略图名称</returns> |
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public string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight) |
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string sThumbFile = "" ; |
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string sFilename = "" ; |
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if (upImage.PostedFile != null ) |
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HttpPostedFile myFile = upImage.PostedFile; |
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int nFileLen = myFile.ContentLength; |
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string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower(); |
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if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp" && extendName != ".png" ) |
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byte [] myData = new Byte[nFileLen]; |
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myFile.InputStream.Read(myData, 0, nFileLen); |
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sFilename = System.IO.Path.GetFileName(myFile.FileName); |
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while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename))) |
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sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) |
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+ file_append.ToString() + extendName; |
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System.IO.FileStream newFile |
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= new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename), |
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System.IO.FileMode.Create, System.IO.FileAccess.Write); |
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newFile.Write(myData, 0, myData.Length); |
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using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename))) |
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int width = sourceImage.Width; |
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int height = sourceImage.Height; |
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if ((( decimal )width) / height <= (( decimal )intThumbWidth) / intThumbHeight) |
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smallWidth = intThumbWidth; |
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smallHeight = intThumbWidth * height / width; |
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smallWidth = intThumbHeight * width / height; |
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smallHeight = intThumbHeight; |
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sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName; |
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while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile))) |
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sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + |
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file_append.ToString() + extendName; |
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string smallImagePath = System.Web.HttpContext.Current.Server.MapPath(sSavePath) + sThumbFile; |
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using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight)) |
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using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap)) |
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g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; |
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g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; |
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g.Clear(Color.Black); |
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new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight), |
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new System.Drawing.Rectangle(0, 0, width, height), |
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System.Drawing.GraphicsUnit.Pixel |
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using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight)) |
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using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1)) |
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g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; |
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g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; |
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g.Clear(Color.Black); |
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int lwidth = (smallWidth - intThumbWidth) / 2; |
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int bheight = (smallHeight - intThumbHeight) / 2; |
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g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel); |
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bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg); |
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System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)); |
HtmlInputFile控件我想大家都应该知道的,就是input type=file....这个会在后面的一起学asp.net章节中讲解