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Image Browser

By default, the Insert Image tool opens a simple dialog that allows you to type in or paste the URL of an image and, optionally, specify a tooltip.

The Editor also supports another way of picking an image by browsing a list of predefined files and directories. Uploading new images is also supported. For a runnable example, refer to the demo on file and image browser in the Editor.

To retrieve and upload the files and directories, the image browser needs a server-side implementation. To configure the image browser tool, use the ImageBrowser() method.

The follwing example demonstrates how to set the ImageBrowser configuration of the Editor and a possible server-side implementation:

@(Html.Kendo().Editor()
    .Name("editor")
    .ImageBrowser(imageBrowser => imageBrowser
        .Image("~/Content/UserFiles/Images/{0}")
        .Read("Read", "ImageBrowser")
        .Create("Create", "ImageBrowser")
        .Destroy("Destroy", "ImageBrowser")
        .Upload("Upload", "ImageBrowser")
        .Thumbnail("Thumbnail", "ImageBrowser")
    )
)
    public class ImageBrowserController : EditorImageBrowserController
    {
        private const string contentFolderRoot = "shared/";
        private const string folderName = "Images/";
        private static readonly string[] foldersToCopy = new[] { "shared/images/employees" };

        /// <summary>
        /// Gets the base paths from which content will be served.
        /// </summary>
        public override string ContentPath
        {
            get
            {
                return CreateUserFolder();
            }
        }

        public ImageBrowserController(IHostingEnvironment hostingEnvironment)
            : base(hostingEnvironment)
        {
        }

        private string CreateUserFolder()
        {
            var virtualPath = Path.Combine(contentFolderRoot, "UserFiles", folderName);
            var path = HostingEnvironment.WebRootFileProvider.GetFileInfo(virtualPath).PhysicalPath;

            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
                foreach (var sourceFolder in foldersToCopy)
                {
                    CopyFolder(HostingEnvironment.WebRootFileProvider.GetFileInfo(sourceFolder).PhysicalPath, path);
                }
            }
            return virtualPath;
        }

        private void CopyFolder(string source, string destination)
        {
            if (!Directory.Exists(destination))
            {
                Directory.CreateDirectory(destination);
            }

            foreach (var file in Directory.EnumerateFiles(source))
            {
                var dest = Path.Combine(destination, Path.GetFileName(file));
                System.IO.File.Copy(file, dest);
            }

            foreach (var folder in Directory.EnumerateDirectories(source))
            {
                var dest = Path.Combine(destination, Path.GetFileName(folder));
                CopyFolder(folder, dest);
            }
        }
    }
    public abstract class EditorImageBrowserController : BaseFileBrowserController, IImageBrowserController
    {
        protected EditorImageBrowserController(IHostingEnvironment hostingEnvironment)
            : this(DI.Current.Resolve<IDirectoryBrowser>(),
                  DI.Current.Resolve<IDirectoryPermission>(),
                  hostingEnvironment)
        {
        }

        protected EditorImageBrowserController(
            IDirectoryBrowser directoryBrowser,
            IDirectoryPermission permission,
            IHostingEnvironment hostingEnvironment)
             : base(directoryBrowser, permission, hostingEnvironment)
        {
        }

        /// <summary>
        /// Gets the valid file extensions by which served files will be filtered.
        /// </summary>
        public override string Filter
        {
            get
            {
                return EditorImageBrowserSettings.DefaultFileTypes;
            }
        }

        public virtual bool AuthorizeThumbnail(string path)
        {
            return CanAccess(path);
        }

        /// <summary>
        /// You can use a third-party library to create thumbnails as System.Drawing is not curretnly part of ASP.NET Core https://blogs.msdn.microsoft.com/dotnet/2016/02/10/porting-to-net-core/
        /// </summary>
        public virtual IActionResult Thumbnail(string path)
        {
            return null;
        }
    }
    public abstract class BaseFileBrowserController : Controller, IFileBrowserController
    {
        private readonly IDirectoryBrowser directoryBrowser;
        private readonly IDirectoryPermission permission;

        protected readonly IHostingEnvironment HostingEnvironment;

        protected BaseFileBrowserController(IHostingEnvironment hostingEnvironment)
            : this(DI.Current.Resolve<IDirectoryBrowser>(),
                  DI.Current.Resolve<IDirectoryPermission>(),
                  hostingEnvironment)
        {
        }

        protected BaseFileBrowserController(
            IDirectoryBrowser directoryBrowser,
            IDirectoryPermission permission,
            IHostingEnvironment hostingEnvironment)
        {
            this.directoryBrowser = directoryBrowser;
            this.directoryBrowser.HostingEnvironment = hostingEnvironment;
            this.permission = permission;
            this.HostingEnvironment = hostingEnvironment;
        }

        /// <summary>
        /// Gets the base path from which content will be served.
        /// </summary>
        public abstract string ContentPath
        {
            get;
        }

        /// <summary>
        /// Gets the valid file extensions by which served files will be filtered.
        /// </summary>
        public virtual string Filter
        {
            get
            {
                return "*.*";
            }
        }

        /// <summary>
        /// Creates a folder with a given entry.
        /// </summary>
        /// <param name="path">The path to the parent folder in which the folder should be created.</param>
        /// <param name="entry">The entry.</param>
        /// <returns>An empty <see cref="ContentResult"/>.</returns>
        /// <exception cref="Exception">Forbidden</exception>
        [AcceptVerbs("POST")]
        public virtual ActionResult Create(string path, FileBrowserEntry entry)
        {
            var fullPath = NormalizePath(path);
            var name = entry.Name;

            if (name.HasValue() && AuthorizeCreateDirectory(fullPath, name))
            {
                var physicalPath = Path.Combine(fullPath, name);

                if (!Directory.Exists(physicalPath))
                {
                    Directory.CreateDirectory(physicalPath);
                }

                return Json(entry);
            }

            throw new Exception("Forbidden");
        }

        /// <summary>
        /// Determines if a folder can be created.
        /// </summary>
        /// <param name="path">The path to the parent folder in which the folder should be created.</param>
        /// <param name="name">Name of the folder.</param>
        /// <returns>true if folder can be created, otherwise false.</returns>
        public virtual bool AuthorizeCreateDirectory(string path, string name)
        {
            return CanAccess(path);
        }

        public virtual JsonResult Read(string path)
        {
            var fullPath = NormalizePath(path);

            if (AuthorizeRead(fullPath))
            {
                try
                {
                    var files = directoryBrowser.GetFiles(fullPath, Filter);
                    var directories = directoryBrowser.GetDirectories(fullPath);
                    var result = files.Concat(directories);

                    return Json(result.ToArray());
                }
                catch (DirectoryNotFoundException)
                {
                    throw new Exception("File Not Found");
                }
            }

            throw new Exception("Forbidden");
        }

        /// <summary>
        /// Determines if content of a given path can be browsed.
        /// </summary>
        /// <param name="path">The path which will be browsed.</param>
        /// <returns>true if browsing is allowed, otherwise false.</returns>
        public virtual bool AuthorizeRead(string path)
        {
            return CanAccess(path);
        }

        protected virtual bool CanAccess(string path)
        {
            var rootPath = Path.GetFullPath(Path.Combine(this.HostingEnvironment.WebRootPath, ContentPath));

            return permission.CanAccess(rootPath, path);
        }

        protected string NormalizePath(string path)
        {
            if (string.IsNullOrEmpty(path))
            {
                return Path.GetFullPath(Path.Combine(this.HostingEnvironment.WebRootPath, ContentPath));
            }
            else
            {
                return Path.GetFullPath(Path.Combine(this.HostingEnvironment.WebRootPath, ContentPath, path));
            }
        }

        /// <summary>
        /// Deletes a entry.
        /// </summary>
        /// <param name="path">The path to the entry.</param>
        /// <param name="entry">The entry.</param>
        /// <returns>An empty <see cref="ContentResult"/>.</returns>
        /// <exception cref="Exception">File Not Found</exception>
        [AcceptVerbs("POST")]
        public virtual ActionResult Destroy(string path, FileBrowserEntry entry)
        {
            var fullPath = NormalizePath(path);

            if (entry != null)
            {
                fullPath = Path.Combine(fullPath, entry.Name);

                if (entry.EntryType == FileBrowserEntryType.File)
                {
                    DeleteFile(fullPath);
                }
                else
                {
                    DeleteDirectory(fullPath);
                }

                return Json(new object[0]);
            }

            throw new Exception("File Not Found");
        }

        /// <summary>
        /// Determines if a file can be deleted.
        /// </summary>
        /// <param name="path">The path to the file.</param>
        /// <returns>true if file can be deleted, otherwise false.</returns>
        public virtual bool AuthorizeDeleteFile(string path)
        {
            return CanAccess(path);
        }

        /// <summary>
        /// Determines if a folder can be deleted.
        /// </summary>
        /// <param name="path">The path to the folder.</param>
        /// <returns>true if folder can be deleted, otherwise false.</returns>
        public virtual bool AuthorizeDeleteDirectory(string path)
        {
            return CanAccess(path);
        }

        protected virtual void DeleteFile(string path)
        {
            if (!AuthorizeDeleteFile(path))
            {
                throw new Exception("Forbidden");
            }

            if (System.IO.File.Exists(path))
            {
                System.IO.File.Delete(path);
            }
        }

        protected virtual void DeleteDirectory(string path)
        {
            if (!AuthorizeDeleteDirectory(path))
            {
                throw new Exception("Forbidden");
            }

            if (Directory.Exists(path))
            {
                Directory.Delete(path, true);
            }
        }


        /// <summary>
        /// Uploads a file to a given path.
        /// </summary>
        /// <param name="path">The path to which the file should be uploaded.</param>
        /// <param name="file">The file which should be uploaded.</param>
        /// <returns>A <see cref="JsonResult"/> containing the uploaded file's size and name.</returns>
        /// <exception cref="Exception">Forbidden</exception>
        [AcceptVerbs("POST")]
        public virtual ActionResult Upload(string path, IFormFile file)
        {
            var fullPath = NormalizePath(path);

            if (AuthorizeUpload(fullPath, file))
            {
                SaveFile(file, fullPath);

                var result = new FileBrowserEntry
                {
                    Size = file.Length,
                    Name = GetFileName(file)
                };

                return Json(result);
            }

            throw new Exception("Forbidden");
        }

        protected virtual void SaveFile(IFormFile file, string pathToSave)
        {
            try
            {
                var path = Path.Combine(pathToSave, GetFileName(file));
                using (var stream = System.IO.File.Create(path))
                {
                    file.CopyTo(stream);
                }
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }

        /// <summary>
        /// Determines if a file can be uploaded to a given path.
        /// </summary>
        /// <param name="path">The path to which the file should be uploaded.</param>
        /// <param name="file">The file which should be uploaded.</param>
        /// <returns>true if the upload is allowed, otherwise false.</returns>
        public virtual bool AuthorizeUpload(string path, IFormFile file)
        {
            return CanAccess(path) && IsValidFile(GetFileName(file));
        }

        private bool IsValidFile(string fileName)
        {
            var extension = Path.GetExtension(fileName);
            var allowedExtensions = Filter.Split(',');

            return allowedExtensions.Any(e => e.Equals("*.*") || e.EndsWith(extension, StringComparison.OrdinalIgnoreCase));
        }

        public virtual string GetFileName(IFormFile file)
        {
            var fileContent = ContentDispositionHeaderValue.Parse(file.ContentDisposition);
            return Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
        }
    }
    public interface IImageBrowserController : IFileBrowserController
    {
        IActionResult Thumbnail(string path);
    }
    public interface IFileBrowserController
    {
        JsonResult Read(string path);

        ActionResult Destroy(string path, FileBrowserEntry entry);

        ActionResult Create(string path, FileBrowserEntry entry);

        ActionResult Upload(string path, IFormFile file);
    }

The following list provides information about the default requests and responses for the Create(), Read(), Destroy(), and Upload() operations.

  • Create()—Makes a POST request for the creation of a directory with the following parameters and does not expect a response.

    { "name": "New folder name", "type": "d", "path": "foo/" }
    
  • Read()—Makes a POST request that contains the path parameter which specifies the path that is browsed and expects a file listing in the following format.

    [
        { "name": "foo.png", "type": "f", "size": 73289 },
        { "name": "bar.jpg", "type": "f", "size": 15289 },
        ...
    ]
    

    name from the previous example is the name of the file or directory, type is either an f for a file or a d for a directory, and size is the file size (optional).

  • Destroy()—Makes a POST request with the following parameters and expects an empty ContentResult as a response:

    Parameter Description
    name The file or the directory that will be deleted.
    path The directory in which the file or the directory resides.
    type The file or the directory that will be deleted (an f or a d).
    size (Optional) The file size, as provided by the Read() response.
  • Upload()—Makes a POST request. The request includes FormData which contains the upload path and the file name and type. Its payload consists of the uploaded file. The expected response is a file object in the following format:

    { "name": "foo.png", "type": "f", "size": 12345 }
    
  • Image()—Used by the Editor to generate the src attribute of the original image when the image is inserted. It results in a GET request generated by the browser for each inserted image. The URL can point to a file system or to a service and is parameterized—the {0} placeholder denotes the path and fileName as received from the Read() service.

You can update all of these requests and responses through the ImageBrowser() configuration. Each of them exposes more options that you can tweak.

ImageBrowser in Razor Page scenario

In order to set up the ImageBrowser of the Telerik UI Editor HtmlHelper for ASP.NET Core component in Razor page scenario, you need to configure the Read , Create, Update and Destroy methods of the ImageBrowser Transport configuration. The URL in these methods should refer the name of the handler in the PageModel. See the implementation details in the example below, and for the full project with RazorPages examples, visit our GitHub repository.

    @(Html.Kendo().Editor()
            .Name("editor")
            .ImageBrowser(imageBrowser => imageBrowser
                .Transport(transport => {
                    transport.Read(r => r.Url("/Editor/ImageBrowser?handler=Read"));
                    transport.Create(c => c.Url("/Editor/ImageBrowser?handler=Create"));
                    transport.Destroy(d => d.Url("/Editor/ImageBrowser?handler=Destroy"));
                    transport.UploadUrl("/Editor/ImageBrowser?handler=Upload");
                    transport.ImageUrl("/Images/{0}");

                })
                .Schema(schema => schema.Model(
                    model => model.Fields(fields => fields
                        .Name(name => name.Field("Name"))
                        .Size(size => size.Field("Size"))
                        .Type(type => type.Field("EntryType"))
                        )
                    )
                )
            )
        )
    public JsonResult OnPostRead(string path)
    {
        var fullPath = NormalizePath(path);

        if (AuthorizeRead(fullPath))
        {
            try
            {
                var files = directoryBrowser.GetFiles(fullPath, Filter);
                var directories = directoryBrowser.GetDirectories(fullPath);
                var result = files.Concat(directories);

                return new JsonResult(result.ToArray());
            }
            catch (DirectoryNotFoundException)
            {
                throw new Exception("File Not Found");
            }
        }

        throw new Exception("Forbidden");
    }

    public JsonResult OnPostCreate(string path, FileBrowserEntry entry)
    {
        var fullPath = NormalizePath(path);
        var name = entry.Name;

        if (name.HasValue() && AuthorizeCreateDirectory(fullPath, name))
        {
            var physicalPath = Path.Combine(fullPath, name);

            if (!Directory.Exists(physicalPath))
            {
                Directory.CreateDirectory(physicalPath);
            }

            return new JsonResult(entry);
        }

        throw new Exception("Forbidden");
    }

    public JsonResult OnPostDestroy(string path, FileBrowserEntry entry)
    {
        var fullPath = NormalizePath(path);

        if (entry != null)
        {
            fullPath = Path.Combine(fullPath, entry.Name);

            if (entry.EntryType == "f")
            {
                DeleteFile(fullPath);
            }
            else
            {
                DeleteDirectory(fullPath);
            }

            return new JsonResult(new object[0]);
        }

        throw new Exception("File Not Found");
    }

    public virtual ActionResult OnPostUpload(string path, IFormFile file)
    {
        var fullPath = NormalizePath(path);

        if (AuthorizeUpload(fullPath, file))
        {
            SaveFile(file, fullPath);

            var result = new FileBrowserEntry
            {
                Size = file.Length,
                Name = GetFileName(file)
            };

            return new JsonResult(result);
        }

        throw new Exception("Forbidden");
    }

See Also

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