Fix zoom domain in fid<->ft transition

src/component/context/processings_mutations_context.api.ts

@@ -23,7 +23,7 @@ import { initializeContoursLevels } from '../../data/data2d/Spectrum2D/contours.
 import type { LiveEdit, State } from '../reducer/Reducer.ts';
 import { setDomain, setMode } from '../reducer/actions/DomainActions.ts';
 import { updateView } from '../reducer/actions/FiltersActions.ts';
-import { restoreLastZoomDomain } from '../reducer/helper/ZoomHistoryManager.ts';
+import { restoreLastZoomUnlessDomainChanged } from '../reducer/helper/ZoomHistoryManager.ts';
 import { getActiveSpectrum } from '../reducer/helper/getActiveSpectrum.ts';
 
 import { useChartData } from './ChartContext.tsx';
@@ -207,6 +207,10 @@ export function useProcessingsMutationsAPI() {
     const operation = spectrum.processings[operationIndex];
     operation.enabled = !operation.enabled;
 
+    // `processSpectrum` mutates the spectrum in place, so capture the current
+    // FID/FT state before processing to detect a FID <-> FT transition.
+    const wasFt = spectrum.info.isFt;
+
     resetSelectedTool();
     await submit(spectrum, indexSpectrum, (draft, processedSpectrum) => {
       if (isSpectrum2D(processedSpectrum) && processedSpectrum.info.isFt) {
@@ -216,7 +220,7 @@ export function useProcessingsMutationsAPI() {
 
       setDomain(draft);
       setMode(draft);
-      restoreLastZoomDomain(draft);
+      restoreLastZoomUnlessDomainChanged(draft, wasFt);
     });
   });
 

src/component/reducer/actions/FiltersActions.ts

@@ -52,7 +52,7 @@ import {
   getDefaultTwoDimensionsPhaseCorrectionTraceOptions,
   getInitialState,
 } from '../Reducer.js';
-import { restoreLastZoomDomain } from '../helper/ZoomHistoryManager.js';
+import { restoreLastZoomUnlessDomainChanged } from '../helper/ZoomHistoryManager.js';
 import { findStrongestPeak } from '../helper/findStrongestPeak.js';
 import { getActiveSpectrum } from '../helper/getActiveSpectrum.js';
 import getRange from '../helper/getRange.js';
@@ -1658,6 +1658,10 @@ export function handleEnableFilter(
   const { id, enabled } = action.payload;
   const datum = draft.data[activeSpectrum.index];
 
+  // `enableFilter` reprocesses the spectrum in place, so capture the current
+  // FID/FT state before to detect a FID <-> FT transition.
+  const wasFt = datum.info.isFt;
+
   //apply filter into the spectrum
   if (isSpectrum1D(datum)) {
     Filters1DManager.enableFilter(datum, { id, enabled });
@@ -1674,7 +1678,7 @@ export function handleEnableFilter(
   resetSelectedTool(draft);
   setDomain(draft);
   setMode(draft);
-  restoreLastZoomDomain(draft);
+  restoreLastZoomUnlessDomainChanged(draft, wasFt);
 }
 
 function deleteFilter(datum: Spectrum, id?: string) {

src/component/reducer/helper/ZoomHistoryManager.ts

@@ -3,6 +3,8 @@ import type { Draft } from 'immer';
 import type { BrushAxis } from '../../EventsTrackers/brush_tracker.types.ts';
 import type { State } from '../Reducer.js';
 
+import { getSpectrum } from './getSpectrum.js';
+
 interface HistoryItem {
   xDomain: number[];
   yDomain: number[];
@@ -117,11 +119,31 @@ export function addToBrushHistory(
   }
 }
 
-export function restoreLastZoomDomain(draft: Draft<State>) {
+interface RestoreLastZoomDomainOptions {
+  /**
+   * Set to true when the displayed spectrum switched between FID and FT.
+   * A FID <-> FT transition regenerates the x axis, so any zoom domain stored
+   * for the previous state is expressed in a different scale and must be
+   * discarded instead of restored (otherwise the previous zoom is applied to
+   * the new axis, e.g. FFT keeps the FID zoom range and only flips the scale).
+   */
+  isFtStateChanged?: boolean;
+}
+
+export function restoreLastZoomDomain(
+  draft: Draft<State>,
+  options: RestoreLastZoomDomainOptions = {},
+) {
   const zoomHistory = zoomHistoryManager(
     draft.zoom.history,
     draft.view.spectra.activeTab,
   );
+
+  if (options.isFtStateChanged) {
+    zoomHistory.clear();
+    return false;
+  }
+
   const zoomValue = zoomHistory.getLast();
 
   if (!zoomValue) {
@@ -133,3 +155,21 @@ export function restoreLastZoomDomain(draft: Draft<State>) {
 
   return true;
 }
+
+/**
+ * Restore the last zoom domain, unless the active spectrum switched between FID
+ * and FT since `previousIsFt` was captured. This is the shared criterion for
+ * every action that re-processes a spectrum (processings panel, legacy filter
+ * panel, FFT): a FID <-> FT transition regenerates the x axis, so the stored
+ * zoom is stale and the freshly computed full domain must be kept instead.
+ */
+export function restoreLastZoomUnlessDomainChanged(
+  draft: Draft<State>,
+  previousIsFt: boolean,
+) {
+  const currentIsFt = getSpectrum(draft)?.info.isFt ?? previousIsFt;
+
+  return restoreLastZoomDomain(draft, {
+    isFtStateChanged: previousIsFt !== currentIsFt,
+  });
+}

src/component/reducer/helper/__tests__/ZoomHistoryManager.test.ts

@@ -0,0 +1,90 @@
+import type { Draft } from 'immer';
+import { expect, test } from 'vitest';
+
+import type { State } from '../../Reducer.ts';
+import {
+  addToBrushHistory,
+  restoreLastZoomDomain,
+  restoreLastZoomUnlessDomainChanged,
+} from '../ZoomHistoryManager.ts';
+
+/**
+ * Minimal draft exposing only what `addToBrushHistory`,
+ * `restoreLastZoomDomain` and `restoreLastZoomUnlessDomainChanged` read from
+ * the reducer state.
+ */
+function createDraft(isFt: boolean): Draft<State> {
+  return {
+    displayerMode: '1D',
+    xDomain: [0, 100],
+    yDomain: [0, 1],
+    yDomains: {},
+    data: [{ info: { isFt } }],
+    view: {
+      spectra: {
+        activeTab: '1H',
+        activeSpectra: { '1H': [{ index: 0, selected: true }] },
+      },
+    },
+    zoom: { history: {} },
+  } as unknown as Draft<State>;
+}
+
+test('restores the last zoom domain when no FID/FT transition happened', () => {
+  const draft = createDraft(false);
+
+  // user brushes a zoom on the current (FID) spectrum
+  addToBrushHistory(draft, { axis: 'X', xDomain: [20, 40], yDomain: [0, 1] });
+  expect(draft.xDomain).toStrictEqual([20, 40]);
+
+  // toggling a processing that does not change the FID/FT state resets the
+  // domain and then restores the user zoom
+  draft.xDomain = [-10, 10];
+  const restored = restoreLastZoomUnlessDomainChanged(draft, false);
+
+  expect(restored).toBe(true);
+  expect(draft.xDomain).toStrictEqual([20, 40]);
+});
+
+test('discards the stale zoom domain on a FID -> FT transition (FFT enabled)', () => {
+  const draft = createDraft(false);
+
+  // user brushes a zoom while the spectrum is in the FID state
+  addToBrushHistory(draft, { axis: 'X', xDomain: [20, 40], yDomain: [0, 1] });
+
+  // enabling FFT switches to FT and recomputes the full domain
+  draft.data[0].info.isFt = true;
+  draft.xDomain = [-10, 10];
+  const restored = restoreLastZoomUnlessDomainChanged(draft, false);
+
+  // the FID zoom must not be applied on the regenerated FT axis
+  expect(restored).toBe(false);
+  expect(draft.xDomain).toStrictEqual([-10, 10]);
+  expect(draft.zoom.history['1H']).toStrictEqual([]);
+});
+
+test('discards the stale zoom domain on a FT -> FID transition (FFT disabled)', () => {
+  const draft = createDraft(true);
+
+  // user brushes a zoom while the spectrum is in the FT state
+  addToBrushHistory(draft, { axis: 'X', xDomain: [2, 4], yDomain: [0, 1] });
+
+  // disabling FFT switches back to FID and recomputes the full domain
+  draft.data[0].info.isFt = false;
+  draft.xDomain = [0, 100];
+  const restored = restoreLastZoomUnlessDomainChanged(draft, true);
+
+  expect(restored).toBe(false);
+  expect(draft.xDomain).toStrictEqual([0, 100]);
+  expect(draft.zoom.history['1H']).toStrictEqual([]);
+});
+
+test('restoreLastZoomDomain keeps its default behaviour (restore when possible)', () => {
+  const draft = createDraft(false);
+
+  addToBrushHistory(draft, { axis: 'X', xDomain: [20, 40], yDomain: [0, 1] });
+  draft.xDomain = [-10, 10];
+
+  expect(restoreLastZoomDomain(draft)).toBe(true);
+  expect(draft.xDomain).toStrictEqual([20, 40]);
+});