服务器上的缩略图 - GDI+ 中发生一般性错误

Question

我们已经解决这个问题很长时间了，并尝试了很多来自网络的不同修复方法。到目前为止没有任何效果。

问题：基本图像保存正常，缩略图保存失败。在下面的解决方案之前，我曾尝试为所有图像（基本图像、600x600 和 300x300 拇指）创建单独的流，但这也没有用。所有的流都是从同一个字节数组构造的。请记住这一点：这在开发环境、测试环境和 Test2 环境中工作得很好，但在生产环境中无法工作。我已经检查了文件夹的所有设置/环境变量/权限，所有设置都与测试环境相同。

路径如下：

基本路径：“~/images/imageUpl/”
缩略图添加。路径："thumbM/"
缩略图添加。路径："thumbS/"
图像名称结构："X_YYYYMMDD_HHMMSS_XX.png"

路径都是正确的 - 因为它适用于 Dev/Test/Test2 环境。

非常感谢任何帮助！

编辑：到目前为止我们尝试了什么：

为网络和 IISUser 设置权限
对从原始源数据构建的每个图像使用单独的流
根据其他示例添加 thread.sleep(30+)
从调整大小的位图创建新的位图并保存它
用于测试其目录在生产环境中是否存在问题的不同路径

编辑 2：作为参考，这是一个 ASP.NET MVC5 Web 应用程序，运行 of .NET Framework 4.7.2。

图像处理器Class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Drawing.Drawing2D;
using Newtonsoft.Json;
using System.Threading;

namespace CMS_MVC.Classes
{
    public class ImageProcessor : IDisposable
    {
        public enum PathType : int
        {
            Relative = 1,
            Static = 2
        }

        private Stream _ImageStream { get; set; }
        private HttpContext _Context { get; set; }
        public Image BaseImage { get; set; }
        private int _instanceId { get; set; }

        public ImageProcessor(int instanceId, Stream imageStream, HttpContext context)
        {
            this._ImageStream = imageStream;
            this._Context = context;
            this._instanceId = instanceId;

            this.BaseImage = Image.FromStream(this._ImageStream);
        }

        public ImageProcessor(int instanceId, byte[] imageByteArray, HttpContext context)
        {
            this._Context = context;
            this._instanceId = instanceId;

            this._ImageStream = new MemoryStream(imageByteArray);
            this.BaseImage = Image.FromStream(this._ImageStream);
        }

        public ImageProcessor(int instanceId, string imagePath, PathType pathType, HttpContext context)
        {
            this._Context = context;
            this._instanceId = instanceId;

            if (pathType == PathType.Relative)
            {
                this._ImageStream = new MemoryStream(File.ReadAllBytes(this._Context.Server.MapPath(imagePath)));
                this.BaseImage = Image.FromStream(this._ImageStream);
            }
            else
            {
                this._ImageStream = new MemoryStream(File.ReadAllBytes(imagePath));
                this.BaseImage = Image.FromStream(this._ImageStream);
            }
        }

        public Dictionary<string, bool> SaveImages(string baseImageSavePath, string imageName, Dictionary<string, Tuple<int, int>> thumbnails = null)
        {
            Dictionary<string, bool> results = new Dictionary<string, bool>();
            string lastResult = "main";
            results.Add(lastResult, true);

            try
            {
                this.BaseImage.Save(this._Context.Server.MapPath(Path.Combine(baseImageSavePath, imageName)), ImageFormat.Png);

                if (thumbnails != null)
                {
                    foreach (var thumbnail in thumbnails)
                    {
                        lastResult = thumbnail.Value.Item1.ToString() + "_" + thumbnail.Value.Item2.ToString();
                        results.Add(lastResult, true);

                        using (Bitmap thumbBitmap = this.ResizeImage(thumbnail.Value.Item1, thumbnail.Value.Item2))
                        {
                            Thread.Sleep(50);
                            thumbBitmap.Save(this._Context.Server.MapPath(Path.Combine(baseImageSavePath + thumbnail.Key, imageName)), ImageFormat.Png);
                            Thread.Sleep(50);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                results[lastResult] = false;

                // Log event
            }

            return results;
        }

        private Bitmap ResizeImage(int targetWidth, int targetHeight)
        {
            Tuple<int, int> destSize = this.CalculateThumbnailSizeAspectRatio(targetWidth, targetHeight);

            var destRect = new Rectangle(0, 0, destSize.Item1, destSize.Item2);
            var destImage = new Bitmap(destSize.Item1, destSize.Item2);

            destImage.SetResolution(this.BaseImage.HorizontalResolution, this.BaseImage.VerticalResolution);

            using (var graphics = Graphics.FromImage(destImage))
            {
                graphics.CompositingMode = CompositingMode.SourceCopy;
                graphics.CompositingQuality = CompositingQuality.HighQuality;
                graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                graphics.SmoothingMode = SmoothingMode.HighQuality;
                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;

                using (var wrapMode = new ImageAttributes())
                {
                    wrapMode.SetWrapMode(WrapMode.TileFlipXY);
                    graphics.DrawImage(this.BaseImage, destRect, 0, 0, this.BaseImage.Width, this.BaseImage.Height, GraphicsUnit.Pixel, wrapMode);
                }
            }

            return destImage;
        }

        private Tuple<int, int> CalculateThumbnailSizeAspectRatio(int targetWidth, int targetHeight)
        {
            // Resize calculations
        }

        public void Dispose()
        {
            if (this._ImageStream != null) this._ImageStream.Dispose();
            if (this.BaseImage != null) this.BaseImage.Dispose();
        }
    }
}

Answer 1

来自 documentation 网站：

Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions.

该站点随后会将您定向到 WIC，但这不是一个好主意。服务器也不支持 WPF Media 类（但缺少关于此的同样明确的声明）。

出现了各种替代方案，这里是an older SO question。

最好的办法是寻找完全托管的解决方案，a.o。图像锐利。

我仍在寻找关于 System.Drawing.Common 的类似声明或见解，一个 .net 核心库。

服务器上的缩略图 - GDI+ 中发生一般性错误

Thumbnails on Server - A generic error occurred in GDI+

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gdi+

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