Add Icons as Labels

[sambowenhughes]

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I would love to be able to add an Icon, parent label, and value inside a tree node. See screenshot:

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More configurations to customize the inner tree node. Adding icons and parent labels.

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[plouc]

@sambowenhughes, this component already has a lot of props, it's impossible to cover every needs, and it would make the API and the implementation quite complex.

This is achievable using a custom component though, you can start with the default node: https://github.com/plouc/nivo/blob/master/packages/treemap/src/TreeMapNode.tsx.