[whatwg] Drag-and-drop folders/files support with directory structure using DirectoryEntry

[Kinuko Yasuda]

Hi,

We'd like to propose (and experiment in Webkit/chromium) exposing
dropped files/folders as {File,Directory}Entry defined in FileSystem
API [1] for better folders/files drag-and-drop support.

[1] File API: Directories and System http://www.w3.org/TR/file-system-api/

Usage scenario:
  Many sites have 'upload your files' feature, like for
  your photo images.  HTML5 allows you to do this via
  <input type="file" multiple> or drag-and-drop feature,
  but the current solution does not provide clean solution
  for cases with folders, files/folder mixed cases, or folders
  with subfolders cases.

  For context, back then we have proposed (and implemented)
  'directory' attribute for <input type=file> specifically to upload
  a directory, but the approach does not provide useful information
  to webapps about which file comes from which folder, neither
  does it allow apps to control how and when to enumerate
  directories (e.g. app cannot show progress meter etc even
  the enumerating part takes long time).
  http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2010-April/025764.html

Proposal:
  Add a new field 'entries' to <input type=files> element
  and to DataTransfer object, and populate the field with
  file or directory 'Entries' defined in FileSystem API [1]
  upon file selection or drop events.

  Since FileSystem API naturally supports tree-structured
  folder hierarchy, Entry object exposes handy fields like 'isFile'
  and 'isDirectory', and allows webapps to recursively walk over
  the nested entries in subfolders via ReadDirectory() method.

  This approach allows webapps to directly interact
  with the local folder structure, and also allows
  them to control the enumerating part so that
  the apps can show nice progress meter if they want.

Security notes:
 The Entries exposed by this feature must be
 read-only and isolated in a special temporary
 filesystem so that the webapps cannot access any
 other folders outside the dropped ones.

Example:
  When I choose or drag-and-drop a set of folders
  in the photos folder like:

    /Users/kinuko/Photos/trip/1.jpg
    /Users/kinuko/Photos/trip/2.jpg
    /Users/kinuko/Photos/trip/3.jpg
    /Users/kinuko/Photos/halloween/a.jpg
    /Users/kinuko/Photos/halloween/b.jpg
    /Users/kinuko/Photos/tokyo/1.jpg
    /Users/kinuko/Photos/tokyo/2.jpg
    ...

  Via the new 'entries' field the site can access each
  subfolder 'trip' or 'halloween' by scripting, and can
  properly organize and process pictures using the local
  folder structure.

  We can think of similar interesting usage scenarios
  like local-cloud sync app or bulk 'importer', e.g. importing
  local source directory to cloud IDE etc.

What are your thoughts about adding folder support using DirectoryEntry?

Thanks,
Kinuko