AUSAXS→SasView Integration Plan (Phase 1 & 2)

[wpotrzebowski]

From KristianL & JanSP (summary):

• Phase 1 (near-term):
  • Hydration layer + SAXS with actual contrast in water buffers using the “simple method” (Lytje & Pedersen, 2025).
  • Swap X-ray form factors with neutron scattering lengths + Debye–Waller factor.
  • Note: C++ interfacing and bandwidth are constraints; will need help from SasView contributors.
• Phase 2 (long-term):
  • Rigid-body optimization incl. assembly symmetries.
  • Requires dedicated GUI and polishing; not yet production-ready in AUSAXS.

Questions/Needs

• Ownership for C++ integration layer
• GUI design partnership for Phase 2
• Incremental milestones users can test early

Checklist

• Spec Phase 1 interfaces & data flow
• Identify owners / PR plan
• Define minimal test datasets & benchmarks

[klytje]

SAXS integration
I'm currently working on the SAXS integration here, but stalled because there is no good way to load both a PDB and data file into SasView. My suggestion is to decouple the "Send to" button from perspectives, and allow it to send arbitrary data to arbitrary windows, which they may then accept or not. This would neatly solve the issue, and allow all file loading to be centralized to the main SasView window (e.g., the nuclear and magnetic data for the GSC could also use this approach). This option would require significant changes to SasView, however.

I eventually settled on including the SAXS fitter as an option in the fit panel instead of adding another tool-specific menu for it. I think this is also an intuitive location for it. However, it will require a custom GUI fitting interface, which I'm not sure is currently supported by SasView.

SANS integration
I haven't done any work on this yet. AUSAXS already has Debye-Waller factors, so if we really only need to add another set of form factors, it will be trivial to implement & integrate into SasView.

C++ interfacing
This is already solved, see pyAUSAXS. Extending this integration to other / new functions of AUSAXS is trivial. The only limitation is GUI support in SasView.

Phase 2
We should discuss exactly what we want so I can list what is already supported & what needs additional work.