在文件上传时调整图像大小 - C#

Question

我想在上传文件时调整图片大小（创建缩略图）。但它似乎没有正确读取路径并且正在崩溃...

代码：

if (FileUpload1.HasFile)
        {
            string imageFile = FileUpload1.FileName;
            string path = "~/images/galeria/" + imageFile;
            cmd.Parameters.Add("@IMAGE_URL", System.Data.SqlDbType.NVarChar).Value = path;
            FileUpload1.SaveAs(Server.MapPath(path));

            System.Drawing.Image image = System.Drawing.Image.FromFile(path);
            float aspectRatio = (float)image.Size.Width / (float)image.Size.Height;
            int newHeight = 200;
            int newWidth = Convert.ToInt32(aspectRatio * newHeight);
            System.Drawing.Bitmap thumbBitmap = new System.Drawing.Bitmap(newWidth, newHeight);
            System.Drawing.Graphics thumbGraph = System.Drawing.Graphics.FromImage(thumbBitmap);
            thumbGraph.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            thumbGraph.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            thumbGraph.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            var imageRectangle = new Rectangle(0, 0, newWidth, newHeight);
            thumbGraph.DrawImage(image, imageRectangle);
            thumbBitmap.Save("~/images/galeria/thumb/" + FileUpload1.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);
            thumbGraph.Dispose();
            thumbBitmap.Dispose();
            image.Dispose();
        }

它正在将图像保存到目录中，但不会读取路径，因此 aspectRatio 无法获取其大小。有什么想法吗？

编辑1：错误信息： 'System.IO.FileNotFoundException' 类型的异常发生在 System.Drawing.dll 但未在用户代码中处理

附加信息：此处为图像路径。

编辑2： System.Drawing.dll 中发生类型 'System.Runtime.InteropServices.ExternalException' 的异常，但未在用户代码中处理附加信息：GDI+ 中发生一般性错误。此行导致错误：

thumbBitmap.Save("~/images/galeria/thumb/" + FileUpload1.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);

Answer 1

使用Server.MapPath(path) 读取路径。您正在使用它来保存而不是阅读。

 if (FileUpload1.HasFile)
        {
            string imageFile = FileUpload1.FileName;
            string path = Server.MapPath("~/images/galeria/" + imageFile);
            FileUpload1.SaveAs(path);

            System.Drawing.Image image = System.Drawing.Image.FromFile(path);
            float aspectRatio = (float)image.Size.Width / (float)image.Size.Height;
            int newHeight = 200;
            int newWidth = Convert.ToInt32(aspectRatio * newHeight);
            System.Drawing.Bitmap thumbBitmap = new System.Drawing.Bitmap(newWidth, newHeight);
            System.Drawing.Graphics thumbGraph = System.Drawing.Graphics.FromImage(thumbBitmap);
            thumbGraph.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            thumbGraph.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            thumbGraph.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            var imageRectangle = new Rectangle(0, 0, newWidth, newHeight);
            thumbGraph.DrawImage(image, imageRectangle);
            thumbBitmap.Save(Server.MapPath("~/images/galeria/thumb/" + FileUpload1.FileName), System.Drawing.Imaging.ImageFormat.Jpeg);
            thumbGraph.Dispose();
            thumbBitmap.Dispose();
            image.Dispose();
        }

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