[GIS] legend groups and layer position/order qgis 1.8

layerspyqgisqgistable of contents

I'm tring to programmatically create layer sequence also using groups.
Simple python code:

layer = QgsVectorLayer("004cp000.shp", "004cp000", "ogr")
QgsMapLayerRegistry.instance().addMapLayer(layer)
legend = qgis.utils.iface.legendInterface()
index = legend.addGroup ("G1")
index = legend.addGroup ("G2",index)
legend.moveLayer (legend.layers()[0],index)

  • How it is possible to remove a nested group ?
    qgis.utils.iface.legendInterface().removeGroup only works with top level groups.

  • How a layer can be moved into a nested group?
    qgis.utils.iface.legendInterface().moveLayer only works with top level groups.

  • How can I move a layer before or after a another layer inside the same group?

After some research into QGis Source code I've discovered that it is not possible to move a layer into a sub group and also it is not possible to delete a soub group.

void QgsLegend::moveLayer( QgsMapLayer *ml, int groupIndex )
{
  if ( !ml )
    return;

  QgsLegendLayer *layer = findLegendLayer( ml->id() );
  if ( !layer )
    return;

  QgsLegendGroup *group = dynamic_cast<QgsLegendGroup*>( topLevelItem( groupIndex ) );
  if ( !group )
    return;

  insertItem( layer, group );

  emit itemMovedGroup( dynamic_cast<QgsLegendItem*>( layer ), groupIndex );
}

void QgsLegend::removeGroup( int groupIndex )
{
  QgsLegendGroup * lg = dynamic_cast<QgsLegendGroup *>( topLevelItem( groupIndex ) );
  if ( lg )
  {
    removeGroup( lg );
  }
}

Best Answer

You should really update QGIS to v.>=2.4. Martin Dobias refactored the QGIS layer list widget (aka legend or ToC), enabling developers to manipulate legend objects from the QGIS API.

Martin has recently posted a couple of articles on how to use the new legend API from Python:

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