computeSankeyNodeVisuals function

List<FluentSankeyNodeVisual> computeSankeyNodeVisuals({ required FluentSankeyLayoutResult layout, required FluentChartTextMeasurer measurer, required TextStyle nameStyle, required TextStyle weightMeasurementStyle, required String formatNumber(double value), required String nodeSemanticLabel(String name, String weight), })

Computes the text visuals for every node.

Ports _computeNodeAttributes (SankeyChart.tsx:619-665). The name budget is NODE_WIDTH - 8 less the padding: 8 on a tall node, and 8 + 6 + weightWidth on a short one, where the weight is measured at weightMeasurementStyle.

Implementation

List<FluentSankeyNodeVisual> computeSankeyNodeVisuals({
  required FluentSankeyLayoutResult layout,
  required FluentChartTextMeasurer measurer,
  required TextStyle nameStyle,
  required TextStyle weightMeasurementStyle,
  required String Function(double value) formatNumber,
  required String Function(String name, String weight) nodeSemanticLabel,
}) {
  final result = <FluentSankeyNodeVisual>[];
  for (var i = 0; i < layout.nodes.length; i++) {
    final node = layout.nodes[i];
    final height = math.max(node.y1 - node.y0, 0.0);
    final actualValue = layout.nodeActualValues[i];
    final formatted = formatNumber(actualValue);
    // `:631` — 8px of left margin inside the rectangle.
    var padding = 8.0;
    var weightOffset = 0.0;
    if (height < kSankeyMinHeightForDoubleLine) {
      // `:638` — 6px of breathing room between the name and the weight.
      padding += 6;
      weightOffset = measurer.width(formatted, weightMeasurementStyle);
      padding += weightOffset;
    }
    // `:647-649` — 124 - 8 = 116 is the rectangle width the truncation works
    // against, and `truncateText` subtracts the padding from it (`:391`).
    final name = truncateSankeyText(
      layout.data.nodes[i].name,
      kSankeyNodeWidth - 8 - padding,
      measurer: measurer,
      style: nameStyle,
    );
    result.add(
      FluentSankeyNodeVisual(
        name: name,
        trimmed: name.endsWith(kSankeyEllipsis),
        height: height,
        weightOffset: weightOffset,
        // `:855` — a falsy 0 bypasses the formatter entirely.
        weightText: actualValue != 0 ? formatted : '0',
        semanticLabel: nodeSemanticLabel(layout.data.nodes[i].name, formatted),
      ),
    );
  }
  return result;
}