Module heatmap 

Heatmap — a rows × cols matrix painted as a colour grid using a theme-derived Ramp, with a gradient legend. The cell-layout math (cell_rect) is a pure function with tests so the grid geometry can be verified headlessly.

Structs

HeatmapState

Persistent, observable interaction state (FC-3): the (row, col) cell the pointer last hovered. Serialized so it round-trips headlessly.

HeatmapView

A dense matrix in row-major order with optional axis labels.

Enums

HeatmapEffect

FC-8: the heatmap does no I/O.

HeatmapMsg

FC-2 input surface. One input: the hovered cell changing (hit-tested purely in HeatmapView::render, applied in HeatmapView::update).

Functions

cell_rect

The pixel rect of cell (row, col) inside grid, given rows × cols. Pure geometry — no painter needed, so it’s directly testable.