feat(chart): support explicit nice x domains

src/components/WaveformChart.vue

@@ -16,6 +16,7 @@ const props = withDefaults(defineProps<WaveformChartProps>(), {
   zoomable: true,
   pannable: false,
   minVisiblePoints: 0,
+  xDomainStrategy: () => ({ type: 'data' }),
   timeUnit: 'ms',
   frameNumber: undefined,
   annotations: () => [],

src/components/core/trackLayoutBuilder.ts

@@ -16,6 +16,7 @@ import type {
   WaveformDisplayMode,
   WaveformOverlayMode,
   WaveformPoint,
+  WaveformXDomainStrategy,
   WaveformXAxisLabelFormatter,
 } from '../../types'
 import { buildMinorTicks, formatXAxisLabel } from '../../utils'
@@ -26,6 +27,7 @@ import {
 } from './grid'
 import { axisTextMetrics, resolveYAxisSeriesGroups } from './layout'
 import type { DisplaySeries, DisplayTrack, TrackLayout, WaveformYAxisLayout } from './types'
+import { applyXDomainStrategy } from './xDomain'
 import {
   Y_AXIS_LABEL_BAND_WIDTH,
   Y_AXIS_LABEL_GAP,
@@ -46,6 +48,7 @@ export interface BuildTrackLayoutsOptions {
   sharedZoomDomain: [number, number]
   initialXDomain?: [number, number]
   initialXDomains?: Record<string, [number, number]>
+  xDomainStrategy?: WaveformXDomainStrategy
   fixedYDomain?: [number, number]
   fixedYDomains?: Record<string, [number, number]>
   yDomains?: Record<string, [number, number]>
@@ -57,6 +60,21 @@ export interface BuildTrackLayoutsOptions {
   showCompactEmptyTracks: boolean
 }
 
+function resolveIndependentXDomain(
+  track: DisplayTrack,
+  seriesId: string,
+  options: BuildTrackLayoutsOptions,
+): [number, number] {
+  const strategy = options.xDomainStrategy ?? { type: 'data' }
+  const explicitDomain =
+    options.initialXDomains?.[track.id] ??
+    options.initialXDomains?.[seriesId] ??
+    options.initialXDomain
+  return explicitDomain
+    ? applyXDomainStrategy(explicitDomain, strategy, true)
+    : applyXDomainStrategy(track.xDomain, strategy)
+}
+
 export function buildTrackLayouts(options: BuildTrackLayoutsOptions): TrackLayout[] {
   const visibleCells = options.cells.map((cell) => ({ ...cell, hasSeries: Boolean(cell.series) }))
   const bottomCells = getBottomRowCellIndexes(visibleCells, options.grid.columnCount)
@@ -88,13 +106,7 @@ export function buildTrackLayouts(options: BuildTrackLayoutsOptions): TrackLayou
     const series = displayTrack.visibleSeries[0] ?? displayTrack.series[0] ?? emptySeries
     const baseXScale =
       options.displayMode === 'independent'
-        ? scaleLinear(
-            options.initialXDomains?.[displayTrack.id] ??
-              options.initialXDomains?.[series.id] ??
-              options.initialXDomain ??
-              displayTrack.xDomain,
-            [0, cell.width],
-          )
+        ? scaleLinear(resolveIndependentXDomain(displayTrack, series.id, options), [0, cell.width])
         : scaleLinear(options.sharedZoomDomain, [0, cell.width])
     const transform =
       options.displayMode === 'independent'

src/components/core/useWaveformChartLifecycle.ts

@@ -204,6 +204,7 @@ export function useWaveformChartLifecycle(context: LifecycleContext) {
       () => props.minVisiblePoints,
       () => props.initialXDomain,
       () => props.initialXDomains,
+      () => props.xDomainStrategy,
       () => props.displayMode,
       () => chartTracks.value.length,
       currentPage,

src/components/core/useWaveformLayout.ts

@@ -34,6 +34,7 @@ import {
 import type { DisplaySeries, DisplayTrack, TrackLayout } from './types'
 import type { PreparedWaveformSeries } from './useWaveformData'
 import type { ResolvedWaveformChartProps } from './waveformChartTypes'
+import { applyXDomainStrategy } from './xDomain'
 import type { useWaveformAnnotationInteraction } from '../annotation'
 
 interface LayoutContext {
@@ -224,9 +225,13 @@ export function useWaveformLayout(context: LayoutContext) {
       Number.isFinite(domain[1]) &&
       domain[0] !== domain[1]
     ) {
-      return domain[0] < domain[1] ? domain : [domain[1], domain[0]]
+      return applyXDomainStrategy(
+        domain[0] < domain[1] ? domain : [domain[1], domain[0]],
+        props.xDomainStrategy,
+        true,
+      )
     }
-    return sharedXDomain.value
+    return applyXDomainStrategy(sharedXDomain.value, props.xDomainStrategy)
   })
   const resolveInitialTrackDomain = (track: TrackLayout): [number, number] => {
     const configuredDomain =
@@ -239,11 +244,18 @@ export function useWaveformLayout(context: LayoutContext) {
       Number.isFinite(configuredDomain[1]) &&
       configuredDomain[0] !== configuredDomain[1]
     ) {
-      return configuredDomain[0] < configuredDomain[1]
-        ? configuredDomain
-        : [configuredDomain[1], configuredDomain[0]]
+      return applyXDomainStrategy(
+        configuredDomain[0] < configuredDomain[1]
+          ? configuredDomain
+          : [configuredDomain[1], configuredDomain[0]],
+        props.xDomainStrategy,
+        true,
+      )
     }
-    return paddedDomain(track.seriesList.flatMap((series) => series.xDomain))
+    return applyXDomainStrategy(
+      paddedDomain(track.seriesList.flatMap((series) => series.xDomain)),
+      props.xDomainStrategy,
+    )
   }
   const sharedZoomDomain = computed(
     () =>
@@ -272,6 +284,7 @@ export function useWaveformLayout(context: LayoutContext) {
       sharedZoomDomain: sharedZoomDomain.value,
       initialXDomain: props.initialXDomain ? initialXDomain.value : undefined,
       initialXDomains: props.initialXDomains,
+      xDomainStrategy: props.xDomainStrategy,
       fixedYDomain: props.yDomain,
       fixedYDomains: props.yDomains,
       yDomains:

src/components/core/waveformChartTypes.ts

@@ -11,6 +11,7 @@ import type {
   WaveformPoint,
   WaveformRenderingOptions,
   WaveformTitleOptions,
+  WaveformXDomainStrategy,
   WaveformZeroLineOptions,
   WaveformZoomEndPayload,
   WaveformZoomResetPayload,
@@ -33,6 +34,7 @@ export interface WaveformChartProps {
   minVisiblePoints?: number
   initialXDomain?: [number, number]
   initialXDomains?: Record<string, [number, number]>
+  xDomainStrategy?: WaveformXDomainStrategy
   yDomain?: [number, number]
   yDomains?: Record<string, [number, number]>
   timeUnit?: 's' | 'ms'
@@ -63,6 +65,7 @@ type DefaultedProp =
   | 'zoomable'
   | 'pannable'
   | 'minVisiblePoints'
+  | 'xDomainStrategy'
   | 'timeUnit'
   | 'annotations'
   | 'annotationsVisible'

src/components/core/xDomain.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, it } from 'vitest'
+
+import { applyXDomainStrategy } from './xDomain'
+
+describe('applyXDomainStrategy', () => {
+  it('keeps the exact data domain by default', () => {
+    expect(applyXDomainStrategy([0, 4999.999], { type: 'data' })).toEqual([0, 4999.999])
+  })
+
+  it('expands both bounds to stable nice values', () => {
+    expect(applyXDomainStrategy([123, 456], { type: 'nice' })).toEqual([100, 500])
+  })
+
+  it('can expand only the end bound', () => {
+    expect(applyXDomainStrategy([123, 456], { type: 'nice', bounds: 'end' })).toEqual([123, 500])
+  })
+
+  it('keeps explicit domains exact unless they are included', () => {
+    expect(applyXDomainStrategy([123, 456], { type: 'nice' }, true)).toEqual([123, 456])
+    expect(applyXDomainStrategy([123, 456], { type: 'nice', includeExplicit: true }, true)).toEqual(
+      [100, 500],
+    )
+  })
+
+  it('falls back to the default tick count for invalid values', () => {
+    expect(applyXDomainStrategy([0, 4999.999], { type: 'nice', tickCount: 0 })).toEqual([0, 5000])
+  })
+})

src/components/core/xDomain.ts

@@ -0,0 +1,25 @@
+import { scaleLinear } from 'd3'
+
+import type { WaveformXDomainStrategy } from '../../types'
+
+const DEFAULT_NICE_TICK_COUNT = 10
+
+function resolveTickCount(value: number | undefined): number {
+  if (!Number.isFinite(value) || (value ?? 0) < 1) return DEFAULT_NICE_TICK_COUNT
+  return Math.max(1, Math.trunc(value as number))
+}
+
+/** Derives a viewport domain without changing any source coordinates. */
+export function applyXDomainStrategy(
+  domain: [number, number],
+  strategy: WaveformXDomainStrategy,
+  explicit = false,
+): [number, number] {
+  if (strategy.type !== 'nice' || (explicit && !strategy.includeExplicit)) return [...domain]
+
+  const niceDomain = scaleLinear()
+    .domain(domain)
+    .nice(resolveTickCount(strategy.tickCount))
+    .domain() as [number, number]
+  return strategy.bounds === 'end' ? [domain[0], niceDomain[1]] : niceDomain
+}

src/components/data/types.ts

@@ -9,6 +9,7 @@ export type {
   WaveformDisplayMode,
   WaveformOverlayMode,
   WaveformInteractionMode,
+  WaveformXDomainStrategy,
   WaveformZoomEndPayload,
   WaveformZoomResetPayload,
   WaveformAnnotationStyle,

src/components/waveform.ts

@@ -9,6 +9,7 @@ export type {
   WaveformDisplayMode,
   WaveformOverlayMode,
   WaveformInteractionMode,
+  WaveformXDomainStrategy,
   WaveformAnnotationStyle,
   WaveformAnnotation,
   WaveformRenderingOptions,

src/components/waveformChartCases/viewportReset.test.ts

@@ -5,6 +5,13 @@ import { flushAnimationFrames } from '../../test/setup'
 import { gridSeries, mountSizedChart } from '../../test/waveformChart'
 
 describe('WaveformChart viewport reset', () => {
+  const niceExplicitStrategy = {
+    type: 'nice' as const,
+    bounds: 'end' as const,
+    tickCount: 10,
+    includeExplicit: true,
+  }
+
   it('resets a shared viewport on double-click and emits a global payload', async () => {
     const wrapper = await mountSizedChart(
       {
@@ -111,4 +118,32 @@ describe('WaveformChart viewport reset', () => {
     expect(wrapper.findAll('.waveform-chart__axis-endpoint--start')[0].text()).toBe('0')
     expect(wrapper.findAll('.waveform-chart__axis-endpoint--end')[0].text()).toBe('1000')
   })
+
+  it('resets shared and independent explicit domains to their included nice bounds', async () => {
+    const shared = await mountSizedChart(
+      {
+        kind: 'points',
+        points: [
+          { x: 0, y: 0 },
+          { x: 4.999999, y: 1 },
+        ],
+      },
+      { initialXDomain: [0, 4.999999], xDomainStrategy: niceExplicitStrategy },
+    )
+    const independent = await mountSizedChart(gridSeries(2), {
+      displayMode: 'independent',
+      initialXDomains: { 'channel-0': [0, 4.999999] },
+      xDomainStrategy: niceExplicitStrategy,
+    })
+
+    ;(shared.vm as unknown as { resetViewport: () => void }).resetViewport()
+    ;(independent.vm as unknown as { resetViewport: () => void }).resetViewport()
+    await flushPromises()
+
+    expect(shared.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(shared.get('.waveform-chart__axis-endpoint--end').text()).toBe('5000')
+    const firstTrack = independent.findAll('.waveform-chart__track')[0]
+    expect(firstTrack.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(firstTrack.get('.waveform-chart__axis-endpoint--end').text()).toBe('5000')
+  })
 })

src/components/waveformChartCases/xDomainStrategy.test.ts

@@ -0,0 +1,96 @@
+import { describe, expect, it } from 'vitest'
+
+import { gridSeries, mountSizedChart } from '../../test/waveformChart'
+
+describe('WaveformChart x domain strategy', () => {
+  it('expands automatic x domains without changing source seconds', async () => {
+    const data = {
+      kind: 'points' as const,
+      points: [
+        { x: 0, y: 0 },
+        { x: 4.999999, y: 1 },
+      ],
+    }
+    const wrapper = await mountSizedChart(data, {
+      timeUnit: 'ms',
+      xDomainStrategy: { type: 'nice', bounds: 'end' },
+    })
+
+    expect(wrapper.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(wrapper.get('.waveform-chart__axis-endpoint--end').text()).toBe('5000')
+    expect(data.points[1]?.x).toBe(4.999999)
+  })
+
+  it('keeps explicit initial x domains exact by default', async () => {
+    const wrapper = await mountSizedChart(
+      {
+        kind: 'points',
+        points: [
+          { x: 123, y: 0 },
+          { x: 456, y: 1 },
+        ],
+      },
+      {
+        timeUnit: 's',
+        initialXDomain: [120, 460],
+        xDomainStrategy: { type: 'nice' },
+      },
+    )
+
+    expect(wrapper.get('.waveform-chart__axis-endpoint--start').text()).toBe('120')
+    expect(wrapper.get('.waveform-chart__axis-endpoint--end').text()).toBe('460')
+  })
+
+  it('keeps explicit per-track initial x domains exact by default', async () => {
+    const wrapper = await mountSizedChart(gridSeries(1), {
+      displayMode: 'independent',
+      initialXDomains: { 'channel-0': [0, 4.999999] },
+      xDomainStrategy: { type: 'nice', bounds: 'end' },
+    })
+
+    expect(wrapper.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(wrapper.get('.waveform-chart__axis-endpoint--end').text()).toBe('4999.999')
+  })
+
+  it('includes an explicit shared initial x domain when requested', async () => {
+    const wrapper = await mountSizedChart(
+      {
+        kind: 'points',
+        points: [
+          { x: 0, y: 0 },
+          { x: 4.999999, y: 1 },
+        ],
+      },
+      {
+        initialXDomain: [0, 4.999999],
+        xDomainStrategy: {
+          type: 'nice',
+          bounds: 'end',
+          tickCount: 10,
+          includeExplicit: true,
+        },
+      },
+    )
+
+    expect(wrapper.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(wrapper.get('.waveform-chart__axis-endpoint--end').text()).toBe('5000')
+  })
+
+  it('includes explicit per-track initial x domains in independent mode', async () => {
+    const wrapper = await mountSizedChart(gridSeries(2), {
+      displayMode: 'independent',
+      grid: { rowCount: 1, columnCount: 2 },
+      initialXDomains: {
+        'channel-0': [0, 4.999999],
+        'channel-1': [10, 14.999999],
+      },
+      xDomainStrategy: { type: 'nice', bounds: 'end', tickCount: 10, includeExplicit: true },
+    })
+
+    const tracks = wrapper.findAll('.waveform-chart__track')
+    expect(tracks[0]?.get('.waveform-chart__axis-endpoint--start').text()).toBe('0')
+    expect(tracks[0]?.get('.waveform-chart__axis-endpoint--end').text()).toBe('5000')
+    expect(tracks[1]?.get('.waveform-chart__axis-endpoint--start').text()).toBe('10000')
+    expect(tracks[1]?.get('.waveform-chart__axis-endpoint--end').text()).toBe('15000')
+  })
+})