Stop subject hierarchy node duplication
Implementation of subject hierarchy 2.0. In a nutshell, what it offers in addition to the current subject hierarchy is:
- Considerably increased speed due to the single subject hierarchy node (instead of duplicate SH node for each data node)
- It is enabled by default, because it does not clutter the MRML scene and there are no special mechanisms to support other hierarchies (no pop-up window when entering the module)
- Support of model and annotation hierarchies in subject hierarchy (subject hierarchy shows the same tree that the Models module shows, and it is handled the same way (atlases, drag&drop, show/hide, etc.)
- Improved drag&drop: re-ordering of items (and restoring the order correctly on complete update), drag&drop to empty area reparents to the scene
- Expand and collapsed states of the items are preserved, and restored when reconstructing the hierarchy
- Subject hierarchy combobox showing a drop-down tree is implemented. It can be added in the modules instead of a simple MRML node selector. This, besides allowing an easier overview of the data, makes it possible to differentiate between nodes that have the same name but belong to different patient or study
- More versatile filtering options in the tree and combobox (name, attribute, level)
- More control over the subject hierarchy Qt model in general, more room for further improvements
Extended information about it can be found on the labs page https://www.slicer.org/wiki/Documentation/Labs/SubjectHierarchy