- Use OCP\Response constants instead of the HTTP error code
- Use checkAppEnabled() instead of OC_App::isEnabled with an if statement
- Remove uneeded variable $baseURL
- Rename $isvalid to $isValid
- adding keep aspect to core/ajax/preview.php
- remove duplicate method Preview::show()
- no more hard coded mimetype of preview
- remove .png from the preview urls
- keep old route preview.png for backwards compatibility
- aspect preserving previews are now cached