How to display file thumbnails on hover with JSON formatting in SharePoint

10 november 2024 Oprindeligt udgivet på alexanderhenkel.dk

Learn how to create a custom JSON formatted column that shows a thumbnail preview of a file in a SharePoint library

JSON formatting

When storing a file in a SharePoint library, a thumbnail preview of the file is available.

We can use that thumbnail to show a preview of the file, using JSON formatting.

SharePoint document library with a file preview icon column that shows a large thumbnail of the file when the user hovers over the icon

Step 1
Create a new text column called File preview

Insert the following code into Column setting -> Format this column

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "style": {
    "display": "=if([$File_x0020_Size] == '0' || [$ContentType] == 'Folder', 'none', 'flex')"
  },
  "children": [
    {
      "elmType": "div",
      "style": {
        "margin-left": "25px"
      },
      "attributes": {
        "iconName": "FileImage",
        "class": "ms-font-xl"
      },
      "customCardProps": {
        "openOnEvent": "hover",
        "formatter": {
          "elmType": "div",
          "style": {
            "width": "450px",
            "height": "600px"
          },
          "children": [
            {
              "elmType": "img",
              "style": {
                "width": "100%",
                "height": "98%"
              },
              "attributes": {
                "src": "=@thumbnail.440x590",
                "alt": "File thumbnail"
              }
            }
          ]
        },
        "directionalHint": "rightCenter",
        "isBeakVisible": true
      }
    }
  ]
}

You can adjust the width/height of the customcardprop (the popup) if you like.

You can also adjust the icon by replacing FileImage.

You can find more columns here

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