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

[kimaidou]

Hi massimo

I completely agree, and would like to avoid the "patch to a fragile system"
you mentionned.

Having the QgsAppLegendItem with properties and methods like you described
it the right way to go IMHO.
The children property will help to re-build the hierarchical tree (instead
of using my algo based on the flat object returned by
groupLayerRelationship, a bit hard to read and understand.).

So + 1 for me :)

Michael

2012/10/4 Massimo <massimo.endrighi at geopartner.it>

> Michael,
>
> the group Id could be the groupIndex. For example:
> GroupA                               [groupIndex=0, itemIndex = 0]
>         Layer1                        [groupIndex=0, itemIndex = 1]
>         GroupB                       [groupIndex=1, itemIndex = 2]
>                 GroupC               [groupIndex=2, itemIndex = 3]
>                         Layer2       [groupIndex=2, itemIndex = 4]
>         GroupA                       [groupIndex=3, itemIndex = 5]
> GroupB                               [groupIndex=4, itemIndex = 6]
>         GroupC                       [groupIndex=5, itemIndex = 7]
>                 Layer3                [groupIndex=5, itemIndex = 8]
>
> In this way you obtain:
> - the groupIndex correspond to legend.layers() list
> ['0.GroupA','1.GroupB','2.GroupC','3.GroupA','4.GroupB','5.GroupC']
> - you can use the groupLayerRelationship to reconstruct the exact hierarchy
> in the same way you are doing now
>
> But, from my point of view, this is like a patch to a fragile system.
> It would be much more useful to expose a property to access the legend
> items
> in terms of QgsAppLegendItem.
>
> The QgsAppLegendItem should be a sort of QgsLegendItem
> (src\app\legend\qgslegenditem.h) that expose the following
>  - type (layer or group)
>  - parent (QgsAppLegendItem)
>  - children (list of QgsAppLegendItem)
>  - expanded
>  - visible
>
> Once you have an item you can do all your business logic.
>
> Please let me know your opinion.
>
> Regard
> Massimo
>
>
> kimaidou wrote
> > Hi massimo,
> >
> > You are right, we must add a id for each group in Qgis. For now, the
> group
> > is defined only with its name, which leads to this kind of behaviour. At
> > the contrary, layers do have an id in Qgis, so you can use the same name
> > for 2 different layers.
> >
> > I think we must enhance a bit the way how groups are handled and provide
> > appropriate public methods like
> > group->id(), ĝetGroup(id), etc.
> >
> > In the lizmap example, I could only use  QgsLegendInterface::groups  wich
> > returns a string list of groups, and groupLayerRelationship which provide
> > a
> > flat list of groups and layers. The latter returns ids of layers, but
> name
> > of groups, so there is no easy way to distinguish to groups with the same
> > name.
> >
> > Michael
> >
> > 2012/10/4 Massimo <
>
> > massimo.endrighi@
>
> > >
> >
> >> Michael,
> >>
> >> thank you for the tip but your code fails under some circumstances. See
> >> attached image.
> >> <
> http://osgeo-org.1560.n6.nabble.com/file/n5006430/lizmap_error.png>
> >>
> >> If you think that you can fix it I will be happy to adopt your
> algorithm,
> >> otherwise we can find a solution adding something to QGis API.
> >>
> >> Regards
> >> Massimo
> >>
> >>
> >> kimaidou wrote
> >> > Hi all,
> >> >
> >> > In Lizmap plugin, I need to display the layer and group tree. You can
> >> find
> >> > some code here :
> >> >
> https://bitbucket.org/mdouchin/lizmapplugin/src/9cdfa856b8f0/lizmap.py
> >> > Line 451 : populateLayerTree
> >> >
> >> > There is some specific lizmap code in there, but you can probably use
> >> some
> >> > of it.
> >> >
> >> > Michael
> >>
> >>
> >>
> >>
> >>
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