Can an ASP.NET MVC controller return an Image?
Asked Answered
A

20

483

Can I create a Controller that simply returns an image asset?

I would like to route this logic through a controller, whenever a URL such as the following is requested:

www.mywebsite.com/resource/image/topbanner

The controller will look up topbanner.png and send that image directly back to the client.

I've seen examples of this where you have to create a View - I don't want to use a View. I want to do it all with just the Controller.

Is this possible?

Anjanetteanjela answered 9/10, 2008 at 5:58 Comment(3)
I asked a similar question here https://mcmap.net/q/81042/-creating-a-private-photo-gallery-using-asp-net-mvc and ended up finding a great guide to do this. I created an ImageResult class following this guide. https://blog.maartenballiauw.be/post/2008/05/13/aspnet-mvc-custom-actionresult.htmlGarvey
If you're wanting to modify the image, use the ImageResizing.Net HttpModule for the best performance. If you don't, a FilePathResult adds only a few percent of overhead. URL rewriting adds slightly less.Albertalberta
Why not using WebApi Controller instead of MVC? ApiController classBullace
B
556

Use the base controllers File method.

public ActionResult Image(string id)
{
    var dir = Server.MapPath("/Images");
    var path = Path.Combine(dir, id + ".jpg"); //validate the path for security or use other means to generate the path.
    return base.File(path, "image/jpeg");
}

As a note, this seems to be fairly efficient. I did a test where I requested the image through the controller (http://localhost/MyController/Image/MyImage) and through the direct URL (http://localhost/Images/MyImage.jpg) and the results were:

  • MVC: 7.6 milliseconds per photo
  • Direct: 6.7 milliseconds per photo

Note: this is the average time of a request. The average was calculated by making thousands of requests on the local machine, so the totals should not include network latency or bandwidth issues.

Besmirch answered 28/8, 2009 at 20:58 Comment(9)
For those that are coming into this question now, this was the solution that worked best for me.Clermontferrand
Great answer Brian. One thing, the contentType parameter in the File() method call should be "image/jpeg" in your example. IE8 pops a download dialog otherwise. Also this answer should be selected.Incretion
This isn't safe code. Letting the user pass a file name (path) like this means they could potentially access files from anywhere on the server. Might want to warn people not to use it as-is.Religious
This answer doesn't make any sense. If you are working with files that are saved on a server inside some folder under your web app root, it is better and faster to just use Views and Html or Url MVC helpers to construct the path to the images for the <img> tag or make your own helpers to render the <img> tag entirely. The only time using FileResult makes sense is when you have files, images or any other kind of byte[] content saved in the datastore.Deettadeeyn
Unless you are constructing the files on the fly as they are needed and caching them once they are created (that's what we do).Besmirch
@mare- you might also do this if you are serving files from a restricted location e.g. you may have images in App_Data that should be sign by some users of your application but not others. Using a controller action to serve them allows you to restrict access.Upend
I'm not positive but a quick test of this solution showed that it ignores the "If-Modified-Since" headers and will always return the file. That may be desireable in some situations but it will circumvent client side caching and hurt performance.Subscribe
As other have mentioned, be cautious in your path building, as I've seen actual production code that allowed user to navigate up a directory with carefully constructed POST or query string: /../../../danger/someFileTheyTHoughtWasInaccessibleOverbid
Yes directory traversal vulnerabilities are no joke.Hein
W
138

Using the release version of MVC, here is what I do:

[AcceptVerbs(HttpVerbs.Get)]
[OutputCache(CacheProfile = "CustomerImages")]
public FileResult Show(int customerId, string imageName)
{
    var path = string.Concat(ConfigData.ImagesDirectory, customerId, "\\", imageName);
    return new FileStreamResult(new FileStream(path, FileMode.Open), "image/jpeg");
}

I obviously have some application specific stuff in here regarding the path construction, but the returning of the FileStreamResult is nice and simple.

I did some performance testing in regards to this action against your everyday call to the image (bypassing the controller) and the difference between the averages was only about 3 milliseconds (controller avg was 68ms, non-controller was 65ms).

I had tried some of the other methods mentioned in answers here and the performance hit was much more dramatic... several of the solutions responses were as much as 6x the non-controller (other controllers avg 340ms, non-controller 65ms).

Wagonette answered 15/4, 2009 at 16:23 Comment(2)
What about image is not modified? FileStreamResult should send 304 when image is not modified since last request.Babel
You can use Path.Combine instead of the concat for safer and more readable code.Piragua
C
104

To expland on Dyland's response slightly:

Three classes implement the FileResult class:

System.Web.Mvc.FileResult
      System.Web.Mvc.FileContentResult
      System.Web.Mvc.FilePathResult
      System.Web.Mvc.FileStreamResult

They're all fairly self explanatory:

  • For file path downloads where the file exists on disk, use FilePathResult - this is the easiest way and avoids you having to use Streams.
  • For byte[] arrays (akin to Response.BinaryWrite), use FileContentResult.
  • For byte[] arrays where you want the file to download (content-disposition: attachment), use FileStreamResult in a similar way to below, but with a MemoryStream and using GetBuffer().
  • For Streams use FileStreamResult. It's called a FileStreamResult but it takes a Stream so I'd guess it works with a MemoryStream.

Below is an example of using the content-disposition technique (not tested):

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult GetFile()
    {
        // No need to dispose the stream, MVC does it for you
        string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "myimage.png");
        FileStream stream = new FileStream(path, FileMode.Open);
        FileStreamResult result = new FileStreamResult(stream, "image/png");
        result.FileDownloadName = "image.png";
        return result;
    }
Cracked answered 29/9, 2009 at 21:59 Comment(3)
The content-disposition part of this post was extremely helpfulAcrodont
VS is telling me that this overload of FileStream() is obsolete.Slaw
Something to note: if you have a comma in your file name, Chrome will reject it with a "too many headers received" error. So replace all commas with a "-" or "".Cracked
L
76

This might be helpful if you'd like to modify the image before returning it:

public ActionResult GetModifiedImage()
{
    Image image = Image.FromFile(Path.Combine(Server.MapPath("/Content/images"), "image.png"));

    using (Graphics g = Graphics.FromImage(image))
    {
        // do something with the Graphics (eg. write "Hello World!")
        string text = "Hello World!";

        // Create font and brush.
        Font drawFont = new Font("Arial", 10);
        SolidBrush drawBrush = new SolidBrush(Color.Black);

        // Create point for upper-left corner of drawing.
        PointF stringPoint = new PointF(0, 0);

        g.DrawString(text, drawFont, drawBrush, stringPoint);
    }

    MemoryStream ms = new MemoryStream();

    image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);

    return File(ms.ToArray(), "image/png");
}
Ligni answered 28/3, 2011 at 11:6 Comment(3)
Thank you. This is perfect for the scenario where a proxy is needed to download an image requiring authentication that cannot be done on the client side.Inspirational
You're forgetting to dispose of a whopping 3 native objects: Font, SolidBrush and Image.Showiness
Suggested improvement here: you create a memory stream, write the data and then create a File result with the data using .ToArray() You could also just call ms.Seek(0, SeekOrigin.Begin) and then return File(ms, "image/png") // return the stream itselfOballa
D
13

You can create your own extension and do this way.

public static class ImageResultHelper
{
    public static string Image<T>(this HtmlHelper helper, Expression<Action<T>> action, int width, int height)
            where T : Controller
    {
        return ImageResultHelper.Image<T>(helper, action, width, height, "");
    }

    public static string Image<T>(this HtmlHelper helper, Expression<Action<T>> action, int width, int height, string alt)
            where T : Controller
    {
        var expression = action.Body as MethodCallExpression;
        string actionMethodName = string.Empty;
        if (expression != null)
        {
            actionMethodName = expression.Method.Name;
        }
        string url = new UrlHelper(helper.ViewContext.RequestContext, helper.RouteCollection).Action(actionMethodName, typeof(T).Name.Remove(typeof(T).Name.IndexOf("Controller"))).ToString();         
        //string url = LinkBuilder.BuildUrlFromExpression<T>(helper.ViewContext.RequestContext, helper.RouteCollection, action);
        return string.Format("<img src=\"{0}\" width=\"{1}\" height=\"{2}\" alt=\"{3}\" />", url, width, height, alt);
    }
}

public class ImageResult : ActionResult
{
    public ImageResult() { }

    public Image Image { get; set; }
    public ImageFormat ImageFormat { get; set; }

    public override void ExecuteResult(ControllerContext context)
    {
        // verify properties 
        if (Image == null)
        {
            throw new ArgumentNullException("Image");
        }
        if (ImageFormat == null)
        {
            throw new ArgumentNullException("ImageFormat");
        }

        // output 
        context.HttpContext.Response.Clear();
        context.HttpContext.Response.ContentType = GetMimeType(ImageFormat);
        Image.Save(context.HttpContext.Response.OutputStream, ImageFormat);
    }

    private static string GetMimeType(ImageFormat imageFormat)
    {
        ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
        return codecs.First(codec => codec.FormatID == imageFormat.Guid).MimeType;
    }
}
public ActionResult Index()
    {
  return new ImageResult { Image = image, ImageFormat = ImageFormat.Jpeg };
    }
    <%=Html.Image<CapchaController>(c => c.Index(), 120, 30, "Current time")%>
Desjardins answered 9/6, 2011 at 6:16 Comment(0)
M
12

Why not go simple and use the tilde ~ operator?

public FileResult TopBanner() {
  return File("~/Content/images/topbanner.png", "image/png");
}
Mcnabb answered 31/10, 2011 at 23:47 Comment(0)
T
11

You can write directly to the response but then it isn't testable. It is preferred to return an ActionResult that has deferred execution. Here is my resusable StreamResult:

public class StreamResult : ViewResult
{
    public Stream Stream { get; set; }
    public string ContentType { get; set; }
    public string ETag { get; set; }

    public override void ExecuteResult(ControllerContext context)
    {
        context.HttpContext.Response.ContentType = ContentType;
        if (ETag != null) context.HttpContext.Response.AddHeader("ETag", ETag);
        const int size = 4096;
        byte[] bytes = new byte[size];
        int numBytes;
        while ((numBytes = Stream.Read(bytes, 0, size)) > 0)
            context.HttpContext.Response.OutputStream.Write(bytes, 0, numBytes);
    }
}
Thenceforth answered 9/10, 2008 at 20:22 Comment(0)
W
8

Below code utilizes System.Drawing.Bitmap to load the image.

using System.Drawing;
using System.Drawing.Imaging;

public IActionResult Get()
{
    string filename = "Image/test.jpg";
    var bitmap = new Bitmap(filename);

    var ms = new System.IO.MemoryStream();
    bitmap.Save(ms, ImageFormat.Jpeg);
    ms.Position = 0;
    return new FileStreamResult(ms, "image/jpeg");
}
Wallywalnut answered 15/10, 2019 at 10:22 Comment(1)
This one sets the filename.Whyte
A
7

UPDATE: There are better options than my original answer. This works outside of MVC quite well but it's better to stick with the built-in methods of returning image content. See up-voted answers.

You certainly can. Try out these steps:

  1. Load the image from disk in to a byte array
  2. cache the image in the case you expect more requests for the image and don't want the disk I/O (my sample doesn't cache it below)
  3. Change the mime type via the Response.ContentType
  4. Response.BinaryWrite out the image byte array

Here's some sample code:

string pathToFile = @"C:\Documents and Settings\some_path.jpg";
byte[] imageData = File.ReadAllBytes(pathToFile);
Response.ContentType = "image/jpg";
Response.BinaryWrite(imageData);

Hope that helps!

Activism answered 9/10, 2008 at 6:28 Comment(1)
and how would this look in the controller's action?Clearsighted
A
7

Solution 1: To render an image in a view from an image URL

You can create your own extension method:

public static MvcHtmlString Image(this HtmlHelper helper,string imageUrl)
{
   string tag = "<img src='{0}'/>";
   tag = string.Format(tag,imageUrl);
   return MvcHtmlString.Create(tag);
}

Then use it like:

@Html.Image(@Model.ImagePath);

Solution 2: To render image from database

Create a controller method that returns image data like below

public sealed class ImageController : Controller
{
  public ActionResult View(string id)
  {
    var image = _images.LoadImage(id); //Pull image from the database.
    if (image == null) 
      return HttpNotFound();
    return File(image.Data, image.Mime);
  }
}

And use it in a view like:

@ { Html.RenderAction("View","Image",new {[email protected]})}

To use an image rendered from this actionresult in any HTML, use

<img src="http://something.com/image/view?id={imageid}>
Aciculate answered 6/7, 2014 at 6:26 Comment(0)
Z
6

This worked for me. Since I'm storing images on a SQL Server database.

    [HttpGet("/image/{uuid}")]
    public IActionResult GetImageFile(string uuid) {
        ActionResult actionResult = new NotFoundResult();
        var fileImage = _db.ImageFiles.Find(uuid);
        if (fileImage != null) {
            actionResult = new FileContentResult(fileImage.Data,
                fileImage.ContentType);
        }
        return actionResult;
    }

In the snippet above _db.ImageFiles.Find(uuid) is searching for the image file record in the db (EF context). It returns a FileImage object which is just a custom class I made for the model and then uses it as FileContentResult.

public class FileImage {
   public string Uuid { get; set; }
   public byte[] Data { get; set; }
   public string ContentType { get; set; }
}
Zebedee answered 10/4, 2018 at 2:9 Comment(0)
W
5

you can use File to return a file like View, Content etc

 public ActionResult PrintDocInfo(string Attachment)
            {
                string test = Attachment;
                if (test != string.Empty || test != "" || test != null)
                {
                    string filename = Attachment.Split('\\').Last();
                    string filepath = Attachment;
                    byte[] filedata = System.IO.File.ReadAllBytes(Attachment);
                    string contentType = MimeMapping.GetMimeMapping(Attachment);

                    System.Net.Mime.ContentDisposition cd = new System.Net.Mime.ContentDisposition
                    {
                        FileName = filename,
                        Inline = true,
                    };

                    Response.AppendHeader("Content-Disposition", cd.ToString());

                    return File(filedata, contentType);          
                }
                else { return Content("<h3> Patient Clinical Document Not Uploaded</h3>"); }

            }
Wnw answered 16/3, 2016 at 14:23 Comment(1)
String.Empty and "" are identical (for this usage). Suggestion: replace that whole test with string.IsNullOrEmpty(test) or maybe even string.IsNullOrWhitespace(test)Keitt
D
4

Look at ContentResult. This returns a string, but can be used to make your own BinaryResult-like class.

Dipteral answered 9/10, 2008 at 6:27 Comment(0)
M
3
if (!System.IO.File.Exists(filePath))
    return SomeHelper.EmptyImageResult(); // preventing JSON GET/POST exception
else
    return new FilePathResult(filePath, contentType);

SomeHelper.EmptyImageResult() should return FileResult with existing image (1x1 transparent, for example).

This is easiest way if you have files stored on local drive. If files are byte[] or stream - then use FileContentResult or FileStreamResult as Dylan suggested.

Monogenetic answered 18/2, 2010 at 12:58 Comment(0)
T
3

Yes you can return Image

public ActionResult GetImage(string imageFileName)
{
    var path = Path.Combine(Server.MapPath("/Images"), imageFileName + ".jpg"); 
    return base.File(path, "image/jpeg");
}

(Please don't forget to mark this as answer)

Tincher answered 17/9, 2020 at 19:43 Comment(0)
F
2

I see two options:

1) Implement your own IViewEngine and set the ViewEngine property of the Controller you are using to your ImageViewEngine in your desired "image" method.

2) Use a view :-). Just change the content type etc.

Footstool answered 9/10, 2008 at 6:26 Comment(2)
This could be trouble due to extra spaces or CRLFs in the View.Bailiff
I was wrong in my last post...msdn.microsoft.com/en-us/library/… You can use WebImage class and WebImage.Write in a view :)Bailiff
F
2

You could use the HttpContext.Response and directly write the content to it (WriteFile() might work for you) and then return ContentResult from your action instead of ActionResult.

Disclaimer: I have not tried this, it's based on looking at the available APIs. :-)

Felspar answered 9/10, 2008 at 6:28 Comment(1)
Yeah I just noticed ContentResult only supports strings, but it's easy enough to make your own ActionResult based class.Dipteral
N
2

I also encountered similar requirement,

So in my case I make a request to Controller with the image folder path, which in return sends back a ImageResult object.

Following code snippet illustrate the work:

var src = string.Format("/GenericGrid.mvc/DocumentPreviewImageLink?fullpath={0}&routingId={1}&siteCode={2}", fullFilePath, metaInfo.RoutingId, da.SiteCode);

                if (enlarged)
                    result = "<a class='thumbnail' href='#thumb'>" +
                        "<img src='" + src + "' height='66px' border='0' />" +
                        "<span><img src='" + src + "' /></span>" +
                        "</a>";
                else
                    result = "<span><img src='" + src + "' height='150px' border='0' /></span>";

And in the Controller from the the image path I produce the image and return it back to the caller

try
{
  var file = new FileInfo(fullpath);
  if (!file.Exists)
     return string.Empty;


  var image = new WebImage(fullpath);
  return new ImageResult(new MemoryStream(image.GetBytes()), "image/jpg");


}
catch(Exception ex)
{
  return "File Error : "+ex.ToString();
}
Nicolis answered 20/8, 2019 at 12:1 Comment(0)
S
2

Read the image, convert it to byte[], then return a File() with a content type.

public ActionResult ImageResult(Image image, ImageFormat format, string contentType) {
  using (var stream = new MemoryStream())
    {
      image.Save(stream, format);
      return File(stream.ToArray(), contentType);
    }
  }
}

Here are the usings:

using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using Microsoft.AspNetCore.Mvc;
Salcido answered 21/12, 2019 at 12:55 Comment(0)
S
1

From a byte[] under Core 3.2, you can use:

public ActionResult Img(int? id) {
    MemoryStream ms = new MemoryStream(GetBytes(id));
    return new FileStreamResult(ms, "image/png");
}
Sensitive answered 24/2, 2022 at 10:55 Comment(0)

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