c# - GDI+ 在 Bitmap.Save 方法中发生一般错误

Question

我正在努力上传该图像的缩略图副本并将其保存在缩略图文件夹中。

我正在使用以下链接:

http://weblogs.asp.net/markmcdonnell/archive/2008/03/09/resize-image-before-uploading-to-server.aspx

但是

newBMP.Save(directory + "tn_" + filename);   

导致异常“GDI+ 中发生一般错误。”

我曾尝试授予文件夹权限，也尝试在保存时使用新的单独 bmp 对象。

编辑:

    protected void ResizeAndSave(PropBannerImage objPropBannerImage)
    {
        // Create a bitmap of the content of the fileUpload control in memory
        Bitmap originalBMP = new Bitmap(fuImage.FileContent);

        // Calculate the new image dimensions
        int origWidth = originalBMP.Width;
        int origHeight = originalBMP.Height;
        int sngRatio = origWidth / origHeight;
        int thumbWidth = 100;
        int thumbHeight = thumbWidth / sngRatio;

        int bannerWidth = 100;
        int bannerHeight = bannerWidth / sngRatio;

        // Create a new bitmap which will hold the previous resized bitmap
        Bitmap thumbBMP = new Bitmap(originalBMP, thumbWidth, thumbHeight);
        Bitmap bannerBMP = new Bitmap(originalBMP, bannerWidth, bannerHeight);

        // Create a graphic based on the new bitmap
        Graphics oGraphics = Graphics.FromImage(thumbBMP);
        // Set the properties for the new graphic file
        oGraphics.SmoothingMode = SmoothingMode.AntiAlias; oGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

        // Draw the new graphic based on the resized bitmap
        oGraphics.DrawImage(originalBMP, 0, 0, thumbWidth, thumbHeight);

        Bitmap newBitmap = new Bitmap(thumbBMP);
        thumbBMP.Dispose();
        thumbBMP = null;

        // Save the new graphic file to the server
        newBitmap.Save("~/image/thumbs/" + "t" + objPropBannerImage.ImageId, ImageFormat.Jpeg);

        oGraphics = Graphics.FromImage(bannerBMP);
        // Set the properties for the new graphic file
        oGraphics.SmoothingMode = SmoothingMode.AntiAlias; oGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

        // Draw the new graphic based on the resized bitmap
        oGraphics.DrawImage(originalBMP, 0, 0, bannerWidth, bannerHeight);
        // Save the new graphic file to the server
        bannerBMP.Save("~/image/" + objPropBannerImage.ImageId + ".jpg");


        // Once finished with the bitmap objects, we deallocate them.
        originalBMP.Dispose();

        bannerBMP.Dispose();
        oGraphics.Dispose();
    }

Answer 1

When either a Bitmap object or an Image object is constructed from a file, the file remains locked for the lifetime of the object. As a result, you cannot change an image and save it back to the same file where it originated. http://support.microsoft.com/?id=814675

A generic error occurred in GDI+, JPEG Image to MemoryStream

Image.Save(..) throws a GDI+ exception because the memory stream is closed

http://alperguc.blogspot.in/2008/11/c-generic-error-occurred-in-gdi.html

编辑:
凭内存写...

save to an 'intermediary' memory stream, that should work

例如试试这个 - 替换

    Bitmap newBitmap = new Bitmap(thumbBMP);
    thumbBMP.Dispose();
    thumbBMP = null;
    newBitmap.Save("~/image/thumbs/" + "t" + objPropBannerImage.ImageId, ImageFormat.Jpeg);

用类似的东西:

string outputFileName = "...";
using (MemoryStream memory = new MemoryStream())
{
    using (FileStream fs = new FileStream(outputFileName, FileMode.Create, FileAccess.ReadWrite))
    {
        thumbBMP.Save(memory, ImageFormat.Jpeg);
        byte[] bytes = memory.ToArray();
        fs.Write(bytes, 0, bytes.Length);
    }
}