C＃图像裁剪调整大小删除

Question

When I try to delete image by using System.IO.File.Delete(....) then I get error exception.

IOException was unhandled by user code

The process cannot access the file 'xxx\\image\\6132_15658422-b0a1-45a9-b0f9-7e9af783ad53_Temp.jpg' because it is being used by another process.

Could anyone please give me suggestion ?

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My main function that crop, resize and delete image by c#.

    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);
        }
    }

For Crop Image Function,

    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;
        }
    }

For Resize Image Function,

    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;
        }

    }

[Updated]

Finally I correct my problem as @landenedge suggested,

          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

Even after you've matched up all your Dispose() statements you will find that you still have problems. Image.FromFile is problematic in any high volume web site. The solution is to use Image.FromStream instead.

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

Using an explicit Dispose() , a using() statement or setting the value to null doesn't solve the issue until a garbage collection happens. Forcing a garbage collection to happen is generally a bad idea.

Answer 2

You need to dispose of the Image you create with FromFile() . Try something like this:

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");
}

Also, don't rethrow exceptions with throw ex; - doing so resets the stack trace and can drop valuable debugging information. Instead, just use throw; .