Slicer — interaction map¶

Every control, key, and gesture in SlicerApp, traced to its handler and the engine call it makes. Status is HOW IT IS — verified against the code with file:line citations — unless a row is explicitly marked otherwise. Both event hops are shown: the shell control raises an event (hop 1), the app subscribes (hop 2). All wiring is code-behind — no MVVM, no ICommand anywhere.

The window's root is a MainWindowShell with IsPlaybackTabVisible="False" (src/SlicerApp/MainWindow.axaml:20); the shell supplies the chrome, the app fills the four regions (src/SlicerApp/MainWindow.axaml:23–99):

flowchart TB
  subgraph W["SlicerApp.MainWindow"]
    L["LeftRegion<br/>layer slider · slice params · Load / Apply"]
    V["ViewportRegion<br/>Canvas 600×600 + ViewportToolbar"]
    I["InspectorRegion<br/>OverlayPanel + FindingsPanel (no Playback)"]
    S["StatusRegion<br/>StatusBar ← Shell.StatusText"]
  end
  L --> ES["EngineSession"]
  V --> VC["ViewportController"]
  I --> VC
  ES --> ABI["NpsAbi → native engine"]
  VC --> ABI

Left bar¶

Hosted in shell:MainWindowShell.LeftRegion as the StackPanel LeftSidebarPanel (MainWindow.axaml:23–69), bound to the SliceParams view-model via left.DataContext = _sliceParams (MainWindow.axaml.cs:68–72).

Slice parameter inputs¶

The AXAML sets no Value= on the NumericUpDowns — the displayed defaults come from the two-way bindings to SliceParams, whose defaults deliberately match the pre-nps-3a3 hard-coded generation call (SliceParams.cs:16–20, 34–36). Editing any of these is UI-only until Apply; values are also re-harvested from the controls in HarvestSliceParamsFromUi (MainWindow.axaml.cs:215–246) as a belt-and-braces against decimal/float binding lag.

Range enforcement lives only on the control min/max — SliceParams has no validation (SliceParams.cs:107–116 is a plain equality-guarded setter).

Other left-bar elements¶

Load vs Apply¶

The two buttons differ in one important way — HOW IT IS:

• Load + Gen + Analyze guards the session, locates the primary Benchy fixture (FixtureLocator.FindPrimaryBenchy3Mf(), FixtureLocator.cs:60–90), errors out if the file is missing, calls _session.LoadModel, sets _modelLoaded = true (MainWindow.axaml.cs:176), then runs RunGenerate(). It does not harvest the sidebar values; first click uses the SliceParams defaults.
• Apply / Regenerate additionally requires _modelLoaded (MainWindow.axaml.cs:200–204) and calls HarvestSliceParamsFromUi() first (215–246), copying each NumericUpDown / CheckBox value into _sliceParams before the same RunGenerate().

RunGenerate() then, in order: builds options via _sliceParams.ToGcodeGenOptions() (MainWindow.axaml.cs:258, SliceParams.cs:88–96), calls _session.GenerateDemoToolpath(options) (261), pushes moves, layer visibility, camera and simulation state into the ViewportController and builds buffers (274–287), runs _session.Analyze(new MaterialProfileOptions("PLA", 210, 60)) (289), loads findings and warp grids (296–297), forces the overlay mode to "thermal" (305–310), applies the overlay, and repaints (312–314). The full click-level chain is in Slicer UI workflows.

Parameter mapping: SliceParams → GcodeGenOptions → NpsGcodeGenParams¶

The full chain from sidebar value to ABI struct — HOW IT IS (SliceParams.cs:88–96, EngineSession.cs:258–269, NpsAbi.cs:132–141):

The app never names the ABI struct itself — packing happens inside EngineSession.GenerateDemoToolpath, per the thin-shell constraint noted in MainWindow.axaml.cs:21–22 and SlicerApp.csproj:20–24. The sole C# [DllImport] home is src/Nps.EngineHost/NpsAbi.cs. See UI → engine calls for the wider call table.

Viewport toolbar¶

ViewportToolbar is code-built (src/Nps.Shell/Controls/ViewportToolbar.cs — there is no .axaml). Ten 32×32 icon buttons, tooltips set via ToolTip.SetTip (ViewportToolbar.cs:120, 135); events raised by lambdas at ViewportToolbar.cs:70–81 and subscribed in InitializeShell (MainWindow.axaml.cs:80–89) — this wiring is character-identical to the Simulator's (see duplication audit).

Canvas gestures¶

The viewport is a fixed 600×600 Canvas (ViewportCanvas, MainWindow.axaml:74). Pointer input is attached by the shell (MainWindowShell.AttachViewportHandlers, MainWindowShell.axaml.cs:256–276) and re-raised verbatim as ViewportPointerPressed/Moved/Released (MainWindowShell.axaml.cs:35–37, handlers :278–291); the app subscribes at MainWindow.axaml.cs:76–78.

Painting is delegated to the shared GcodeToolpathPainter.RenderTo(...) (MainWindow.axaml.cs:622–631) — the Slicer passes the full path (maxMoveIndexExclusive: vp.MoveCount, :630); the painter re-projects every move through NpsAbi.ProjectOrbitXY (GcodeToolpathPainter.cs:160–163) and never clears the canvas — the app clears at :606.

Inspector panels¶

Overlay panel (PanelOverlays, MainWindow.axaml:83, Title "Overlays (Slicer)")¶

Five radios in OverlayPanel.axaml:10–14 (GroupName="OverlayMode"). Each fires OnRadioButtonChecked (OverlayPanel.axaml.cs:98–108) → hop 1 ModeChanged(string) (OverlayPanel.axaml.cs:66) → hop 2 app subscription MainWindow.axaml.cs:99 → OnOverlayModeChanged (:509–513) → ApplyCurrentOverlay() (:516–558).

Return path: legend min/max, stats text, IsOverlayActive written to the panel (MainWindow.axaml.cs:530–546), RenderViewport() recolors extrudes via NpsAbi.ViewportGetHeatmapColor (GcodeToolpathPainter.cs:171–184), status "Overlay '{mode}' applied (Slicer parity)." / "Overlay cleared…" (:550–557). After every Load/Apply the mode is forced to "thermal" (MainWindow.axaml.cs:305–310) — set unconditionally because Avalonia suppresses equal-value property changes, so ModeChanged would not fire on a second load.

Findings panel (PanelFindings, MainWindow.axaml:87, initially IsVisible="False")¶

Filter chips are shell-internal (no app subscription, UI-only): ChipAll (FindingsPanel.axaml:38 → OnChipAllClick FindingsPanel.axaml.cs:268–274), severity chips ChipCritical, ChipWarning, ChipInfo (:40–44 → OnChipSeverityClick :276–303), and seven category chips ChipCatThermal, ChipCatStructural, ChipCatMotion, ChipCatHole, ChipCatRetraction, ChipCatFlow, ChipCatUnknown (:52–64 → OnChipCategoryClick :305–322). Each updates an immutable FindingsFilterState (FindingsFilterState.cs:95–135) and reassigns FindingsList.ItemsSource once (FindingsPanel.axaml.cs:342–351). There is no search TextBox.

There is no playback scrubber mirror in the Slicer (comment MainWindow.axaml.cs:419) — selection is highlight-only.

Window keys¶

KeyDown on the window (MainWindow.axaml:8) → OnKeyDown (MainWindow.axaml.cs:136–151) → ShellKeybindings.Handle (ShellKeybindings.cs:82–113), which handles exactly four keys:

Playback is absent by design: no PlaybackPanel (PanelPlayback) is mounted, the activity tab is hidden via IsPlaybackTabVisible="False" (MainWindow.axaml:20, MainWindowShell.axaml.cs:180), and the comment at MainWindow.axaml:89–90 states the panel is intentionally omitted. No scrubber gestures exist in this app — the scrubber lives in the Simulator only.

Chrome: collapse, splitters, activity tabs, status bar¶

All shell-internal; the app's only subscription is the activity-tab click.

Dead code: OnActivityTabClick(object?, RoutedEventArgs) (MainWindow.axaml.cs:504–507) forwards to Shell.Activity.HandleClick but has no callers and no XAML hookup.

See also¶

• Slicer — how it is for the pipeline narrative behind these handlers.
• Slicer UI workflows for the click-level chain of every workflow, each hop with file:line and its test coverage.
• Simulator — interaction map for the same map with playback; the toolbar, slider, overlay, and gesture blocks are near-verbatim clones of this one.
• Duplication audit for which of these blocks the analysis says to move into the shell.