d3-svg-legend/src/size.js

A legend component for d3. Given a d3.scale it can create either a color legend, size legend, or symbol legend.

import helper from "./legend"
import { dispatch } from "d3-dispatch"
import { scaleLinear } from "d3-scale"
import { formatLocale, formatSpecifier } from "d3-format"
import { sum, max } from "d3-array"

export default function size() {
  let scale = scaleLinear(),
    shape = "rect",
    shapeWidth = 15,
    shapePadding = 2,
    cells = [5],
    cellFilter,
    labels = [],
    classPrefix = "",
    title = "",
    locale = helper.d3_defaultLocale,
    specifier = helper.d3_defaultFormatSpecifier,
    labelOffset = 10,
    labelAlign = "middle",
    labelDelimiter = helper.d3_defaultDelimiter,
    labelWrap,
    orient = "vertical",
    ascending = false,
    path,
    titleWidth,
    legendDispatcher = dispatch("cellover", "cellout", "cellclick")

  function legend(svg) {
    const type = helper.d3_calcType(
        scale,
        ascending,
        cells,
        labels,
        locale.format(specifier),
        labelDelimiter
      ),
      legendG = svg.selectAll("g").data([scale])

    if (cellFilter) {
      helper.d3_filterCells(type, cellFilter)
    }

    legendG
      .enter()
      .append("g")
      .attr("class", classPrefix + "legendCells")

    let cell = svg
      .select("." + classPrefix + "legendCells")
      .selectAll("." + classPrefix + "cell")
      .data(type.data)
    const cellEnter = cell
      .enter()
      .append("g")
      .attr("class", classPrefix + "cell")
    cellEnter.append(shape).attr("class", classPrefix + "swatch")

    let shapes = svg.selectAll(
      "g." + classPrefix + "cell " + shape + "." + classPrefix + "swatch"
    )

    //add event handlers
    helper.d3_addEvents(cellEnter, legendDispatcher)

    cell
      .exit()
      .transition()
      .style("opacity", 0)
      .remove()

    shapes
      .exit()
      .transition()
      .style("opacity", 0)
      .remove()
    shapes = shapes.merge(shapes)

    //creates shape
    if (shape === "line") {
      helper.d3_drawShapes(shape, shapes, 0, shapeWidth)
      shapes.attr("stroke-width", type.feature)
    } else {
      helper.d3_drawShapes(
        shape,
        shapes,
        type.feature,
        type.feature,
        type.feature,
        path
      )
    }

    const text = helper.d3_addText(
      svg,
      cellEnter,
      type.labels,
      classPrefix,
      labelWrap
    )

    // we need to merge the selection, otherwise changes in the legend (e.g. change of orientation) are applied only to the new cells and not the existing ones.
    cell = cellEnter.merge(cell)

    //sets placement

    const textSize = text.nodes().map(d => d.getBBox()),
      shapeSize = shapes.nodes().map((d, i) => {
        const bbox = d.getBBox()
        const stroke = scale(type.data[i])

        if (shape === "line" && orient === "horizontal") {
          bbox.height = bbox.height + stroke
        } else if (shape === "line" && orient === "vertical") {
          bbox.width = bbox.width
        }
        return bbox
      })

    const maxH = max(shapeSize, d => d.height + d.y),
      maxW = max(shapeSize, d => d.width + d.x)

    let cellTrans,
      textTrans,
      textAlign = labelAlign == "start" ? 0 : labelAlign == "middle" ? 0.5 : 1

    //positions cells and text
    if (orient === "vertical") {
      const cellSize = textSize.map((d, i) =>
        Math.max(d.height, shapeSize[i].height)
      )
      const y =
        shape == "circle" || shape == "line" ? shapeSize[0].height / 2 : 0
      cellTrans = (d, i) => {
        const height = sum(cellSize.slice(0, i))

        return `translate(0, ${y + height + i * shapePadding})`
      }

      textTrans = (d, i) => `translate( ${maxW + labelOffset},
          ${shapeSize[i].y + shapeSize[i].height / 2 + 5})`
    } else if (orient === "horizontal") {
      cellTrans = (d, i) => {
        const width = sum(shapeSize.slice(0, i), d => d.width)
        const y = shape == "circle" || shape == "line" ? maxH / 2 : 0
        return `translate(${width + i * shapePadding}, ${y})`
      }

      const offset = shape == "line" ? maxH / 2 : maxH
      textTrans = (d, i) => {
        return `translate( ${shapeSize[i].width * textAlign + shapeSize[i].x},
              ${offset + labelOffset})`
      }
    }

    helper.d3_placement(orient, cell, cellTrans, text, textTrans, labelAlign)
    helper.d3_title(svg, title, classPrefix, titleWidth)

    cell.transition().style("opacity", 1)
  }

  legend.scale = function(_) {
    if (!arguments.length) return scale
    scale = _
    return legend
  }

  legend.cells = function(_) {
    if (!arguments.length) return cells
    if (_.length > 1 || _ >= 2) {
      cells = _
    }
    return legend
  }

  legend.cellFilter = function(_) {
    if (!arguments.length) return cellFilter
    cellFilter = _
    return legend
  }

  legend.shape = function(_, d) {
    if (!arguments.length) return shape
    if (_ == "rect" || _ == "circle" || _ == "line") {
      shape = _
      path = d
    }
    return legend
  }

  legend.shapeWidth = function(_) {
    if (!arguments.length) return shapeWidth
    shapeWidth = +_
    return legend
  }

  legend.shapePadding = function(_) {
    if (!arguments.length) return shapePadding
    shapePadding = +_
    return legend
  }

  legend.labels = function(_) {
    if (!arguments.length) return labels
    labels = _
    return legend
  }

  legend.labelAlign = function(_) {
    if (!arguments.length) return labelAlign
    if (_ == "start" || _ == "end" || _ == "middle") {
      labelAlign = _
    }
    return legend
  }

  legend.locale = function(_) {
    if (!arguments.length) return locale
    locale = formatLocale(_)
    return legend
  }

  legend.labelFormat = function(_) {
    if (!arguments.length) return legend.locale().format(specifier)
    specifier = formatSpecifier(_)
    return legend
  }

  legend.labelOffset = function(_) {
    if (!arguments.length) return labelOffset
    labelOffset = +_
    return legend
  }

  legend.labelDelimiter = function(_) {
    if (!arguments.length) return labelDelimiter
    labelDelimiter = _
    return legend
  }

  legend.labelWrap = function(_) {
    if (!arguments.length) return labelWrap
    labelWrap = _
    return legend
  }

  legend.orient = function(_) {
    if (!arguments.length) return orient
    _ = _.toLowerCase()
    if (_ == "horizontal" || _ == "vertical") {
      orient = _
    }
    return legend
  }

  legend.ascending = function(_) {
    if (!arguments.length) return ascending
    ascending = !!_
    return legend
  }

  legend.classPrefix = function(_) {
    if (!arguments.length) return classPrefix
    classPrefix = _
    return legend
  }

  legend.title = function(_) {
    if (!arguments.length) return title
    title = _
    return legend
  }

  legend.titleWidth = function(_) {
    if (!arguments.length) return titleWidth
    titleWidth = _
    return legend
  }

  legend.on = function() {
    const value = legendDispatcher.on.apply(legendDispatcher, arguments)
    return value === legendDispatcher ? legend : value
  }

  return legend
}