[mythtv-commits] Ticket #2594: Add multiselect configuration control

[MythTV]

#2594: Add multiselect configuration control
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 Reporter:  mythtv at dadeos.freeserve.co.uk  |       Owner:  ijr    
     Type:  enhancement                    |      Status:  new    
 Priority:  minor                          |   Milestone:  unknown
Component:  mythtv                         |     Version:  head   
 Severity:  medium                         |  
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 This patch expands the functionality of the SelectSetting class in order
 to provide multi-select capability.

 The new implementation stores a multi-selection (from a QListBox) as a ‘;’
 delimited string in the database. It preserves the order in which
 selections are made (in order to provide order preference) and treats
 single-selection functionality (e.g. from a QComboBox) as a special case
 of multi-selection.

 The new implementation also provides an “expand” policing mechanism. This
 is in order to filter erroneous settings (usually from the database) from
 appearing in selections. Also to this end, it declares the “SetValue()”
 member function as private so that the setting of a selection control to
 an arbitrary value is prohibited. When the system contains a selection
 option, for which a number of potential choices are available, and there
 is the ability to set arbitrary values (which ultimately may not match any
 of the expected selections) it can cause problems.

 In order to facilitate a multi-selection widget, minor modification were
 made to the MythListBox class. These result in Left/Right action mapping
 to Select/Deselect the current item (in a toggle manner). These actions
 used to cause navigation to the next/previous widget. I made this change
 for two reasons, one is that it is in keeping with the logic of most of
 the other widgets (namely, up/down cycles through widgets, and left/right
 changes values), but also I have found that using left/right for
 navigation often results in moving to the next widget and then changing
 its value (if it’s a widget that doesn’t support left/right navigation). I
 personally feel this provides a more uniform user experience (but would
 accept that this navigation is not ideal with long lists).

 A few bugs, or potential bugs, were addressed along the way. There was a
 selection bug on first entering a MythListBox. There were also situations
 where the selection displayed by the Qt widget could become out of sync
 with the underlying SelectSetting state (mainly in situations where the
 state was updated programmatically for which signals indicating a
 selection change are not generated by the Qt widgets).

 All of the other changes were required in order to overcome “SetValue()”
 becoming private.

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Ticket URL: <http://svn.mythtv.org/trac/ticket/2594>
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