[Qgis-developer] index in self.legend.groupLayerRelationship - different behavior between QGIS 1.8 and master?

[Etienne Tourigny]

On Fri, Oct 5, 2012 at 6:28 AM, Massimo <massimo.endrighi at geopartner.it> wrote:
> Etienne Tourigny-3 wrote
>> .....
>> While it woulf be good to expose legend api to python, it mught be a
>> lot of work.
>
> Yes it could be a lot of work and I'm not sure about how to do it.
>
>
> Etienne Tourigny-3 wrote
>> would it be sufficient to have the following?
>>
>> 1) groups relations like this:
>> QList< QPair< int, QList < int > > >
>>
>> 2) layers within a group like this:
>> QList< QPair< int, QList< QString > > >
>> or
>> QList< QPair< int, QList< QgsMapLayer* > > >
>>
>> this way, you have access to group hierarchies by id, and layers for each
>> group.
>>
>> You would use existing methods like setGroupExpanded() to work on
>> groups in a relatively simple manner.
>
> Using the index instead of group name is a good idea. Anyway, the groups
> relations could be recursive in order to avoid a "complex" algorithm to
> reconstruct the hierarchy.
> Furthermore splitting the information over two lists cuts off the exact
> sequence of layers/groups and any post processing logic will fail to
> reconstruct  the hierarchy.

OK, i see how this could fail.

>
> Thus I propose another solution based on QDomDocument similar to the one
> adopted into the QgsLegend::writeProject method.
> The returned document will contain only groups and layers names and indexes,
> like the following example:
> <!DOCTYPE Group Layer Hierarchy>
> <Legend>
>  <Group Name="G0" Index="0">
>   <Layer GroupIndex="0" Id="L020120904162647883" Name="L0" Index="0"/>
>   <Group Name="G1" Index="1">
>    <Group Name="G2" Index="2">
>     <Layer GroupIndex="2" Id="L120120904162647883" Name="L1" Index="1"/>
>     <Layer GroupIndex="2" Id="L220120904162647382" Name="L2" Index="2"/>
>     <Layer GroupIndex="2" Id="L320120904162644097" Name="L3" Index="3"/>
>    </Group>
>    <Group Name="G3" Index="3">
>     <Layer GroupIndex="3" Id="L40120904162648624" Name="L4" Index="4"/>
>    </Group>
>    <Group Name="G4" Index="4">
>     <Layer GroupIndex="4" Id="L520120904162649445" Name="L5" Index="5"/>
>    </Group>
>   </Group>
>  </Group>
> </Legend>

xml stuff is good for export/import but not very handy for
modifications, so this isn't a viable solution

I'll give a -1 on your implementation as it's another stop-gap solution.

I'd support either Martin's solution or exposing the QgsLegend and
related classes to python. But even there,  GroupLayerInfo and
QgsLegend::groupLayerRelationship() have to be modified, or dropped.

cheers
Etienne

>
> Massimo
>
>
>
>
>
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