GDI+ 發生一般性錯誤解決辦法

錯誤的代碼g對象繼續占用 未釋放資源 如果路徑不一樣 沒問題 相同路徑 獲取圖片進行

縮略會造成GDI錯誤

/// <summary>
        /// 生成縮略圖
        /// </summary>
        /// <param name="originalImagePath">源圖路徑（物理路徑）</param>
        /// <param name="thumbnailPath">縮略圖路徑（物理路徑）</param>
        /// <param name="width">縮略圖寬度</param>
        /// <param name="height">縮略圖高度</param> 

        public void CreateMinImage(string originalImagePath, string thumbnailPath, int width, int height)
        {
            System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

            int towidth = width;
            int toheight = height;

            int ow = originalImage.Width;
            int oh = originalImage.Height;

            //新建一個bmp圖片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一個畫板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);


            //設置高質量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //設置高質量,低速度呈現平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空畫布並以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);

            //在指定位置並且按指定大小繪制原圖片的指定部分
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight));

            try
            {
                //以jpg格式保存縮略圖
                string FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
//這里報錯               bitmap.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }

        }

//修改后的代碼
public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)
        {
            Graphics draw = null;
            string FileExt = "";

            System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

            int towidth = width;
            int toheight = height;

            int ow = originalImage.Width;
            int oh = originalImage.Height;

            //新建一個bmp圖片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
            System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);
            //新建一個畫板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);


            //設置高質量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //設置高質量,低速度呈現平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空畫布並以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);

            //在指定位置並且按指定大小繪制原圖片的指定部分
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight));

            try
            {
                //以jpg格式保存縮略圖
                FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
　　　　　　　　　　//用新建立的image對象拷貝bitmap對象 讓g對象可以釋放資源
                draw = Graphics.FromImage(bitmap2);
                draw.DrawImage(bitmap, 0, 0);

            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
　　　　　　　　　　//保存調整在這里即可
                bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        }