[Bugs] #2400 UNSP: Object Chooser API awkward / too limited

[Sugar Labs Bugs]

#2400: Object Chooser API awkward / too limited
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    Reporter:  sascha_silbe               |          Owner:  alsroot          
        Type:  enhancement                |         Status:  new              
    Priority:  Unspecified by Maintainer  |      Milestone:  1.0              
   Component:  journal                    |        Version:  Git as of bugdate
    Severity:  Major                      |       Keywords:                   
Status_field:  New                        |   Distribution:                   
   Seeta_dev:                             |  
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 The
 [http://git.sugarlabs.org/projects/sugar/repos/mainline/blobs/master/src/jarabe/journal/objectchooser.py
 Object Chooser API] is rather awkward to work with if one wants to let the
 user select a specific kind of object from the Journal. {{{what_filter}}}
 takes a single string which is either the bundle ID of an activity or the
 name of a [https://api.sugarlabs.org/epydocs/sugar.mime-
 module.html#GENERIC_TYPE_TEXT generic MIME type collection] (e.g.
 'Audio'). There is no way to select objects
 1. that are not part of a predefined collection (e.g. a TIFF image as TIFF
 is not yet part of the 'Image' collection) or
 2. have a specific MIME type (e.g. only Ogg Vorbis audio files, but no
 MP3s).

 From an API point of view, passing a query dictionary like we do in
 [http://git.sugarlabs.org/projects/sugar-
 toolkit/repos/mainline/blobs/master/src/sugar/datastore/datastore.py
 sugar.datastore.datastore.find()] would be a good way to approach this.
 I'm not sure about the UI part, though: Currently we use the what_filter
 to preselect the
 [https://wiki.sugarlabs.org/go/Design_Team/Designs/Object_Chooser "What"
 combo box]. Some parts of a query dictionary translate more or less easily
 into the existing filters while others have no UI equivalent at all.

 A compromise might be supporting only specific filters, but with a clean
 API. E.g.
 [https://wiki.sugarlabs.org/go/Design_Team/Designs/Object_Chooser#03 one
 of the mockups] explains:

 > The object chooser supports some extra parameters from activities,
 including lists of filters and mime-types.  The filter list specifies
 presets for the controls in the toolbar, for instance allowing an "insert
 image" button to automatically filter for all entries of type "image". A
 boolean for each specified filter determines whether or not the preset is
 locked, or remains adjustable by the child. The mime-type list specifies
 the formats which the activity can support. Items which do not match on
 this list and therefore cannot be selected are rendered with gray text,
 and do not receive a highlight on rollover.

-- 
Ticket URL: <http://bugs.sugarlabs.org/ticket/2400>
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