Function axisSelectionPolygons

packages/sanddance/src/axisSelection.ts:72–111

(axis: VegaDeckGl.types.Axis, vertical: boolean, axisSelectionType: AxisSelectionType, column: Column)

}

function axisSelectionPolygons(axis: VegaDeckGl.types.Axis, vertical: boolean, axisSelectionType: AxisSelectionType, column: Column) {
    const polygons: SelectPolygon[] = [];
    const size = 50;
    const getSearch: { (a, c, i): SearchExpressionGroup } =
        axisSelectionType === 'exact' ?
            (a, c, i) => ({ expressions: [selectExactAxis(a, c, i)] })
            :
            selectBetweenAxis;
    const { domain, ticks } = axis;
    if (ticks.length > 0 && domain) {
        const dim = vertical ? 1 : 0;
        const between = Math.abs(ticks[0].sourcePosition[dim] - domain.sourcePosition[dim]) > 1;
        let divisions: number[];
        if (between) {
            divisions = [];
            for (let i = 1; i < ticks.length; i++) {
                divisions.push((ticks[i].sourcePosition[dim] + ticks[i - 1].sourcePosition[dim]) / 2);
            }
        } else {
            divisions = ticks.slice(1, -1).map(tick => tick.sourcePosition[dim]);
        }

        const add = (p2: number, i: number) => {
            const coords: VegaDeckGl.Position[] = [[p1, q1], [p2, q1], [p2, q2], [p1, q2]];
            polygons.push({
                search: getSearch(axis, column, i),
                polygon: vertical ? coords.map(xy => xy.reverse() as VegaDeckGl.Position) : coords,
            });
            p1 = p2;
        };

        let p1 = domain.sourcePosition[dim];
        const q1 = domain.sourcePosition[vertical ? 0 : 1];
        const q2 = q1 - size;

        divisions.forEach(add);
        add(domain.targetPosition[dim], ticks.length - (between ? 1 : 2));
    }
    return polygons;
}

function facetSelectionPolygons(facetRects: VegaDeckGl.types.FacetRect[]) {
    const polygons: SelectPolygon[] = [];