import { Selection } from 'd3';



// https://stackoverflow.com/questions/17883655/svg-shadow-cut-off
export function addDropShadowFilter(svg: Selection<any, any, HTMLElement, any>, dx = 1, dy = 1, stdDeviation = 4): void {
    const defs = svg.append('defs');
    const filter = defs.append('filter')
        .attr('id', 'dropshadow')
        .attr('y', '-90%') // This positions the filter so that it starts before the element. Preventing cut-off lines
        .attr('x', '-90%')
        .attr('height', '300%')
        .attr('width', '300%');
    filter.append('feGaussianBlur')
        .attr('in', 'SourceAlpha')
        .attr('stdDeviation', stdDeviation)
        .attr('result', 'blur');
    filter.append('feOffset')
        .attr('in', 'blur')
        .attr('dx', dx)
        .attr('dy', dy)
        .attr('result', 'offsetBlur');

    const feMerge = filter.append('feMerge');

    feMerge.append('feMergeNode')
        .attr('in', 'offsetBlur');
    feMerge.append('feMergeNode')
        .attr('in', 'SourceGraphic');
}