Function highchartsToMaidr

Converts a rendered Highcharts chart into a MAIDR data structure.

The chart must already be rendered (i.e. the SVG DOM exists) so that CSS selectors can be generated for element highlighting.

Supported Highcharts series types:

• bar, column → TraceType.BAR
• line, spline → TraceType.LINE, or TraceType.STEP when the series sets step
• area, areaspline → TraceType.AREA
• scatter → TraceType.SCATTER, or TraceType.DOT on a category axis (a Cleveland dot plot)
• lollipop → TraceType.LOLLIPOP
• timeline → TraceType.SCATTER, each event named on its point
• funnel, pyramid → TraceType.FUNNEL
• wordcloud → TraceType.WORD_CLOUD
• sankey, arcdiagram → TraceType.SANKEY
• dependencywheel → TraceType.CHORD
• networkgraph → TraceType.NETWORK
• treemap → TraceType.TREEMAP
• sunburst → TraceType.SUNBURST
• gauge, solidgauge, bullet → TraceType.GAUGE
• waterfall → TraceType.WATERFALL
• errorbar → TraceType.ERROR_BAR, taking its estimates from the series it is linked to
• dumbbell → TraceType.DUMBBELL
• gantt, xrange → TraceType.GANTT
• boxplot → TraceType.BOX
• heatmap → TraceType.HEATMAP
• map (Highmaps) → TraceType.CHOROPLETH
• mapbubble → TraceType.CHOROPLETH, taking its value from the marker size Highcharts names z
• mappoint → TraceType.SCATTER of degrees east against degrees north, each place on ScatterPoint.label
• tilemap → TraceType.HEXBIN, or TraceType.HEATMAP when its tileShape is square (an aligned grid rather than a stagger)
• histogram → TraceType.HISTOGRAM
• candlestick, ohlc, hlc → TraceType.CANDLESTICK, the last without an opening price and so without a body, a trend or a pattern
• pie (including doughnuts, which are a pie with an innerSize) → TraceType.PIE
• Stacked column/bar → TraceType.STACKED
• Grouped (dodged) column/bar → TraceType.DODGED
• Percent-stacked column/bar → TraceType.NORMALIZED
• Stacked area/areaspline → TraceType.STACKED_AREA
• Percent-stacked area/areaspline → TraceType.NORMALIZED_AREA
• Two stacked column/bar series growing opposite ways → TraceType.DIVERGING

Two chart-wide drawing modes override the series types above, because they change what a series means without changing what it is called:

• chart.polar → TraceType.RADAR for line/spline/area series, TraceType.POLAR_AREA for column/bar ones
• chart.parallelCoordinates → TraceType.PARALLEL

Two more are read from the data or declared by the caller, because Highcharts draws them with a series type it shares with something else:

• line/spline series carrying a rank permutation on a reversed axis → TraceType.BUMP, forced or suppressed with options.bump
• scatter series named by options.significancePlot → TraceType.VOLCANO or TraceType.MANHATTAN, merged into one layer

Two more are declared on the series itself, in the maidr block of Highcharts' reserved custom subspace, because nothing in the chart object says what the drawing means:

• custom.maidr = { type: 'survival' } on a stepped line series → TraceType.SURVIVAL, absorbing a linked scatter as its censoring ticks and a linked arearange as its confidence band
• custom.maidr = { type: 'forest', … } on the estimate series → TraceType.FOREST, taking its interval from the errorbar linked over it and its weights, pooled row and null line from the declaration

Multi-pane charts (multiple yAxis/xAxis entries laid out as separate bands, e.g. the Highstock price + volume pattern) are detected from the rendered axis geometry and emitted as a MAIDR subplot grid — one subplot per pane, navigable with arrow keys. Ambiguous layouts (overlapping bands, dual-axis overlays) fall back to today's single-subplot output.