THUMBNAIL.md

Thumbnail

General

• Thumbnails are created by special column name '_thumbnail'.
• The given parameter controls size and secure/public access mode.
• The thumbnails are stored in a public available directory or in a access protected directory. Both directories are central configured in config.qfq.ini.
• The column '_thumbnail' checks if the thumbnail already exist or if it has to be created first.
• Cleaning the thumbnail directory is fine at any time. The next page reload will recreate any needed thumbs.
• The thumbnail filename is a MD5 hash of the original pathFilename. To detect any modified source, the timestamp of source has to be older than of the thumbnail.
• SVG files will be rendered by 'inkscape'.
• All other file formats are rendered by GraphicsMagick 'convert'.
• The rendering process starts the rendering in the background. Therefore QFQ returns quickly, even for several new thumbnails.
• Secured thumbnails will detect if there is a rendering process pending: before the rendering starts, the thumbnail will be created as an empty file. Public thumbnails are not protected. The client has to reload the page.

Secured by SIP

Thumbnails might contain sensitive data and needs to be protected by SIP.

QFQ / report generates a <img src="api/download.php?s=..."> HTML tag.

If a thumbnail file is empty, api/download.php will wait up to ten seconds and than returning a 404.

Public

Saved in a public readable directory, referenced like <img src="<public dir>/<hash>.png">

How to use thumbnails

Report column '_thumbnail'

Secure: SELECT 'T:<pathFilename>|[W:[<width>][x<Height>]]' AS _thumbnail >> Public: SELECT 's:0|T:<pathFilename>|[W:[<width>][x<Height>]]' AS _thumbnail >>

Report column '_link'

Part of a '_link' definition. Secure or Public access is equal to the link itself.

Form

Inside of a form with the new feature #5422 {{COLUMN '...' AS _thumbnail}}

Workflow

Report creates a SIP: