feat(chart): support configurable plot margins

src/components/core/constants.ts

@@ -7,6 +7,9 @@
 /** 图表边距 */
 export const margin = { top: 18, right: 24, bottom: 52, left: 64 }
 
+/** Distance from the drawing SVG bottom edge to the X-axis title baseline. */
+export const X_AXIS_TITLE_BOTTOM_OFFSET = 12
+
 /**
  * 图表最小高度（像素）
  */

src/components/core/useWaveformLayout.ts

@@ -24,7 +24,6 @@ import {
   normalizeGridOptions,
   paginateSeries,
   resolveGridCellGeometry,
-  X_AXIS_BAND,
 } from './grid'
 import {
   buildTrackLayouts,
@@ -316,7 +315,6 @@ export function useWaveformLayout(context: LayoutContext) {
         )
       : [],
   )
-  const xAxisTitleY = computed(() => innerHeight.value + X_AXIS_BAND + 10)
   const editorSeries = computed<AnnotationSeriesInfo | undefined>(() => {
     const seriesId = annotationInteraction.editorDraft.value?.annotation.seriesId
     const series = chartSeries.value.find((item) => item.id === seriesId)
@@ -360,7 +358,6 @@ export function useWaveformLayout(context: LayoutContext) {
     resolveSeriesYScale,
     annotationTrackLayouts,
     renderedAnnotations,
-    xAxisTitleY,
     editorSeries,
     resolveFrameNumber,
   }

src/components/core/useWaveformPresentation.ts

@@ -7,6 +7,7 @@ import {
   TITLE_CHAR_WIDTH_RATIO,
   TITLE_DEFAULT_FONT_SIZE,
   TITLE_LINE_HEIGHT,
+  X_AXIS_TITLE_BOTTOM_OFFSET,
   ZERO_LINE_DEFAULTS,
 } from './constants'
 import { calculateRotatedTitleLayout, TITLE_AREA_HORIZONTAL_PADDING } from './title'
@@ -144,11 +145,23 @@ export function useWaveformPresentation(context: PresentationContext) {
   const titleAreaHeight = computed(() =>
     titleAreaReserved.value ? titleLayout.value.areaHeight : 0,
   )
-  const chartTopMargin = computed(() => margin.top)
+  const resolvePlotMargin = (value: number | undefined, fallback: number) =>
+    typeof value === 'number' && Number.isFinite(value) && value >= 0 ? value : fallback
+  const resolvedPlotMargin = computed(() => ({
+    top: resolvePlotMargin(props.plotMargin.top, margin.top),
+    bottom: resolvePlotMargin(props.plotMargin.bottom, margin.bottom),
+  }))
+  const chartTopMargin = computed(() => resolvedPlotMargin.value.top)
   const drawingHeight = computed(() =>
     Math.max(0, chartHeight.value - titleAreaHeight.value - paginationBandHeight.value),
   )
-  const innerHeight = computed(() => Math.max(0, drawingHeight.value - margin.top - margin.bottom))
+  const xAxisTitleY = computed(() => Math.max(0, drawingHeight.value - X_AXIS_TITLE_BOTTOM_OFFSET))
+  const innerHeight = computed(() =>
+    Math.max(
+      0,
+      drawingHeight.value - resolvedPlotMargin.value.top - resolvedPlotMargin.value.bottom,
+    ),
+  )
   const titleAreaStyle = computed<CSSProperties>(() => ({
     height: `${titleAreaHeight.value}px`,
     justifyContent:
@@ -193,8 +206,10 @@ export function useWaveformPresentation(context: PresentationContext) {
     titleMeasureStyle,
     titleLayout,
     titleAreaHeight,
+    resolvedPlotMargin,
     chartTopMargin,
     drawingHeight,
+    xAxisTitleY,
     innerHeight,
     titleAreaStyle,
     titleVisualStyle,

src/components/core/waveformChartTypes.ts

@@ -7,6 +7,7 @@ import type {
   WaveformInteractionMode,
   WaveformLegendOptions,
   WaveformOverlayMode,
+  WaveformPlotMargin,
   WaveformPoint,
   WaveformRenderingOptions,
   WaveformTitleOptions,
@@ -42,6 +43,7 @@ export interface WaveformChartProps {
   interactionMode?: WaveformInteractionMode
   grid?: WaveformGridOptions
   rendering?: WaveformRenderingOptions
+  plotMargin?: WaveformPlotMargin
   title?: WaveformTitleOptions
   legend?: WaveformLegendOptions
   hiddenSeriesIds?: string[]
@@ -65,6 +67,7 @@ type DefaultedProp =
   | 'annotationsVisible'
   | 'grid'
   | 'rendering'
+  | 'plotMargin'
   | 'legend'
   | 'defaultHiddenSeriesIds'
   | 'cleanView'