C#图像裁剪调整大小删除

Question

当我尝试使用System.IO.File.Delete(....)删除图像时，会出现错误异常。

IOException was unhandled by user code

The process cannot access the file 'xxximage6132_15658422-b0a1-45a9-b0f9-7e9af783ad53_Temp.jpg' because it is being used by another process.

有人能给我建议吗？

---

我的主要功能是通过c#裁剪、调整大小和删除图像。

    int X1 = 70, Y1 = 20, X2 = 201, Y2 = 236, w = 800, h = 600;
    string filelocation = "image/6132_15658422-b0a1-45a9-b0f9-7e9af783ad53_Temp.jpg";
    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            using (System.Drawing.Image _Image = cropImage(
                                                ResizeImage(
                                                        System.Drawing.Image.FromFile( Server.MapPath("~") +"/"+  filelocation), w, h),
                                                        (new System.Drawing.Rectangle(X1, Y1, X2, Y2))))
            {
                _Image.Save(Server.MapPath("~") + "/" + "image/output.jpg");
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally {
            File.Delete(Server.MapPath("~") + "/" + filelocation);
        }
    }

对于裁剪图像功能，

    public System.Drawing.Image cropImage(System.Drawing.Image image, Rectangle cropArea)
    {
        try
        {
            Bitmap bmpImage = new Bitmap(image);
            Bitmap bmpCrop = bmpImage.Clone(cropArea,
            bmpImage.PixelFormat);
            return (System.Drawing.Image)(bmpCrop);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

对于调整图像大小功能，

    public System.Drawing.Image ResizeImage(System.Drawing.Image image, int maxWidth, int maxHeight)
    {
        try
        {
            var ratioX = (double)maxWidth / image.Width;
            var ratioY = (double)maxHeight / image.Height;
            var ratio = Math.Min(ratioX, ratioY);
            var newWidth = (int)(image.Width * ratio);
            var newHeight = (int)(image.Height * ratio);
            var newImage = new Bitmap(newWidth, newHeight);
            Graphics.FromImage(newImage).DrawImage(image, 0, 0, newWidth, newHeight);
            return newImage;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

[更新]

最后，我按照@landenedge的建议纠正了我的问题，

          using (var mainImage = System.Drawing.Image.FromFile(Server.MapPath("~") +"/"+  filelocation)){
                using (System.Drawing.Image _Image = cropImage(
                                                    ResizeImage(mainImage, w, h),
                                                            (new System.Drawing.Rectangle(X1, Y1, X2, Y2))))
                {
                    _Image.Save(Server.MapPath("~") + "/" + "image/output.jpg");
                }
            }

Answer 1

即使匹配了所有Dispose()语句，您也会发现仍然存在问题。Image.FromFile在任何大容量网站中都是有问题的。解决方案是使用Image.FromStream。

   using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
   {
     using (Image original = Image.FromStream(fs))
     {
      ...

使用显式Dispose()、using()语句或将值设置为null并不能解决问题，直到发生垃圾回收。强制进行垃圾收集通常是个坏主意。

Answer 2

您需要处理使用FromFile()创建的Image。试试这样的东西：

using (var mainImage = Image.FromFile(Server.MapPath("~") +"/"+  filelocation), w, h))
using (var _Image = cropImage(ResizeImage(mainImage, new Rectangle(X1, Y1, X2, Y2))))
{
    _Image.Save(Server.MapPath("~") + "/" + "image/output.jpg");
}

此外，不要使用throw ex;重新抛出异常——这样做会重置堆栈跟踪，并可能丢弃有价值的调试信息。相反，只需使用throw;。