Retrieve Images from Image Library in thumbnail format using Rest API

Question

I am trying to retrieve Images from Image Library using Rest API from a mobile device (hence, no cross site calls)..

I am using this approach (https://stackoverflow.com/questions/16893729/how-to-retrieve-image-files-from-sharepoint-image-library-list-through-rest-ap ) to get file binaries directly, not the server relative URL to avoid cross site requests.

I am able to get the images, however since I want to create a picture gallery on my phone, I want to download thumbnails first and then full image once you click on thumbnail.

Is there any way to get thumbnails using Rest API?

Answer 1

It seems SharePoint generates thumbnail file name using the following format:

thumbnailUrl = <filename>_<fileextension>.jpg 

Based on that, the following REST endpoint shows to get thumbnail file content:

/_api/web/getfilebyserverrelativeurl('{thumbnailUrl}')/$value

Example

var webUrl = "https://tenant.sharepoint.com";
var fileUrl = "/PublishingImages/sample.png";

var client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

var requestUrl = String.Format("{0}/_api/web/getfilebyserverrelativeurl('{1}')/$value",webUrl,GetThumbnailUrl(fileUrl));
var response = client.GetAsync(requestUrl, HttpCompletionOption.ResponseHeadersRead).Result;
var fileContent = response.Content.ReadAsByteArrayAsync().Result;

where

public static string GetThumbnailUrl(string fileUrl)
{
    return System.IO.Path.GetFileNameWithoutExtension(fileUrl) + "_" + System.IO.Path.GetExtension(fileUrl) +".jpg";
}

Update

Probably the better option would be to get image thumbnail url via EncodedAbsThumbnailUrl property:

• Get image thumbnail url using request: /_api/web/lists/getbytitle('<image library title>')/items(<item id>)?$select=EncodedAbsThumbnailUrl
• then request thumbnail file content: /_api/web/getfilebyserverrelativeurl('{thumbnailUrl}')/$value