Annotated Heatmap: automatic font color

Given an annotated heatmap I would expect the cell text to contrast with the cell color.
(Not doing so leads to the readability issues in the current documentation/example of Annotated Heatmap: https://plotly.net/simple-charts/heatmaps.html)

A good contrast is shown and discussed on the python side of plotly: https://github.com/plotly/plotly.py/issues/1300

When I did not find a way to do that, I looked at the implementation of AnnotatedHeatmap.
Here the configuration of the annotations is not dependent on the actual cell values - I could only apply a workaround of setting a background color.
I did not find/check the actual layouting step if there is a better place to compute correct font color.

Commencez par lire l’implémentation de AnnotatedHeatmap ainsi que la documentation ou l’exemple de annotated heatmap liés dans l’issue, puis comparez le comportement du contraste abordé dans plotly.py issue 1300. Déterminez à quel endroit la couleur de la police des annotations peut tenir compte des valeurs des cellules et terminez lorsque le texte annoté reste lisible sur l’ensemble des couleurs de la heatmap.