Question

我在使用Magick.NET时遇到了一些问题。我试图将我从URL下载的图像转换为内存流，然后我尝试将图像转换为png。我的代码执行没有任何错误，文件被创建（和上传）但由于某种原因，文件是0kb并且是不可读的。

我的班级看起来像这样：

/// <summary>
/// Used to help with image control
/// </summary>
public class ImageProvider
{

    // Private property for the azure container
    private readonly CloudBlobContainer container;

    /// <summary>
    /// Default constructor
    /// </summary>
    public ImageProvider()
    {

        // Get our absolute path to our ghostscript files
        var path = HostingEnvironment.MapPath("~/App_Data/Ghostscript");

        // Set our ghostscript directory
        MagickNET.SetGhostscriptDirectory(path);

        // Assign our container to our controller
        var storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["AzureStorage"].ConnectionString);
        var blocClient = storageAccount.CreateCloudBlobClient();
        this.container = blocClient.GetContainerReference("kudos-sports");

        // Create the container if it doesn't already exist
        container.CreateIfNotExists();

        // Give public access to the blobs
        container.SetPermissions(new BlobContainerPermissions
        {
            PublicAccess = BlobContainerPublicAccessType.Blob
        });
    }

    /// <summary>
    /// Uploads an image to the azure storage container
    /// </summary>
    /// <param name="provider">The multipart memorystream provider</param>
    /// <returns></returns>
    public async Task<string> UploadImageAsync(MultipartMemoryStreamProvider provider)
    {

        // Read our content
        using (var content = provider.Contents.FirstOrDefault())
        {

            // If the content is empty, throw an error
            if (content == null)
                throw new Exception("The file was not found.");

            // Create a new blob block to hold our image
            var extension = this.GetFileExtension(content);
            var blockBlob = container.GetBlockBlobReference(Guid.NewGuid().ToString() + extension);

            // Upload to azure
            var stream = await content.ReadAsStreamAsync();
            await blockBlob.UploadFromStreamAsync(stream);

            // Return the blobs url
            return blockBlob.StorageUri.PrimaryUri.ToString();
        }
    }

    public async Task<string> ConvertImage(string path)
    {

        // Create our web client
        using (var client = new WebClient())
        {

            // Get our data as bytes
            var data = client.DownloadData(path);

            // Create our image
            using (var image = new MagickImage(data))
            {

                // Create a new memory stream
                using (var memoryStream = new MemoryStream())
                {

                    // Set to a png
                    image.Format = MagickFormat.Png;
                    image.Write(memoryStream);

                    // Create a new blob block to hold our image
                    var blockBlob = container.GetBlockBlobReference(Guid.NewGuid().ToString() + ".png");

                    // Upload to azure
                    await blockBlob.UploadFromStreamAsync(memoryStream);

                    // Return the blobs url
                    return blockBlob.StorageUri.PrimaryUri.ToString();
                }
            }
        }
    }

    /// <summary>
    /// Deletes and image from the azure storage container
    /// </summary>
    /// <param name="name">The name of the file to delete</param>
    public void DeleteImage(string name)
    {

        // Get our item
        var blockBlob = container.GetBlockBlobReference(name);

        // Delete the item
        blockBlob.Delete();
    }

    /// <summary>
    /// Gets the extension from a file
    /// </summary>
    /// <param name="content">The HttpContent of an uploaded file</param>
    /// <returns></returns>
    private string GetFileExtension(HttpContent content)
    {

        // Get our filename
        var filename = content.Headers.ContentDisposition.FileName.Replace("\"", string.Empty);

        // Split our filename
        var parts = filename.Split('.');

        // If we have any parts
        if (parts.Length > 0)
        {

            // Get our last part
            var extension = parts[parts.Length - 1];

            // Return our extension
            return "." + extension;
        }

        // If we don't have an extension, mark as png
        return ".png";
    }
}

转换方法似乎有问题，但我无法弄清问题是什么。有谁知道问题可能是什么？

Answer 1

在将内存流上传到azure之前，您应该将内存流的位置移回到开头：

image.Write(memoryStream);

// Create a new blob block to hold our image
var blockBlob = container.GetBlockBlobReference(Guid.NewGuid().ToString() + ".png");

 // Upload to azure
 memoryStream.Position = 0;
 await blockBlob.UploadFromStreamAsync(memoryStream);

P.S。如果您想在商业产品（http://ghostscript.com/doc/9.16/Commprod.htm）中使用它，请注意您需要Ghostscript的许可证。

Magick.Net将ai转换为png

1 个答案: