# OL3-ext: layer preview

Get a preview image for a layer.
It will add a getPreview(lonlat, res) function to layers to get an image preview of it.

- The function return an array of previews (group layers will return a preview for each layers in it).
- You can add a preview image on layer that has no preview (vector layers for examples).
- See how it runs on Layer switcher image example.

Preview: