sankeyTitleHeight function
Height the chart reserves above the plot for its title.
Ports SankeyChart.tsx:554-560: a title costs its font size plus
CHART_TITLE_PADDING, floored at 36; no title still reserves 36.
Implementation
double sankeyTitleHeight({String? chartTitle, double? titleFontSize}) =>
chartTitle != null
// 13 is upstream's fallback title size (`SankeyChart.tsx:556`).
? math.max(
(titleFontSize ?? 13) + kChartTitlePadding,
kSankeyMinTitleHeight,
)
: kSankeyMinTitleHeight;