My U.S. Map (Canvas) / pbogden

pbogden

Workspace

Published

mapping

Edited

Apr 12, 2019

2 forks

3 stars

projection = d3.geoAlbersUsa().scale(1280).translate([480, 300])

point

{

let counties = topojson.feature(us, us.objects.counties)

let county = counties.features.find(feature => d3.geoContains(feature, point))

return (!county) ? "Outside" : county.properties.ADMIN_NAME + ", " + county.properties.STATE

}

viewof point = {

const height = Math.round(width * 600 / 960);

const context = DOM.context2d(width, height);

const path = d3.geoPath(projection, context);

const pointPath = d3.geoPath(projection, context);

const scale = width / 960;

context.scale(scale, scale);

context.lineJoin = "round";

context.lineCap = "round";

context.beginPath();

path(topojson.mesh(us, us.objects.counties, (a, b) => a !== b && (a.id / 1000 | 0) === (b.id / 1000 | 0)));

context.lineWidth = 0.5 / scale;

context.strokeStyle = "#aaa";

context.stroke();

context.beginPath();

path(topojson.mesh(us, us.objects.states, (a, b) => a !== b));

context.lineWidth = 0.5 / scale;

context.strokeStyle = "#000";

context.stroke();

context.beginPath();

path(topojson.feature(us, us.objects.nation));

context.lineWidth = 1 / scale;

context.strokeStyle = "#000";

context.stroke();

context.lineWidth = 2, context.strokeStyle = "#f00";

const image = context.getImageData(0, 0, context.canvas.width, context.canvas.height);

function render(coordinates) {

context.canvas.value = coordinates;

context.clearRect(0, 0, width, height);

context.putImageData(image, 0, 0);

context.beginPath(), pointPath({type: "Point", coordinates: coordinates}), context.stroke();

}

context.canvas.onmousemove = ({layerX, layerY}) => {

render(projection.invert([layerX / scale, layerY / scale]));

context.canvas.dispatchEvent(new CustomEvent("input"));

};

context.canvas.onmouseout = () => {

render(dc);

context.canvas.dispatchEvent(new CustomEvent("input"));

};

render(dc);

return context.canvas;

}

us = d3.json('https://pbogden.com/mapping/data/topojson/us-10m.json')

us_no_metadata = fetch("https://cdn.jsdelivr.net/npm/us-atlas@2/us/10m.json").then(response => response.json())

topojson = require("topojson-client@3")

d3 = require("d3@5", "d3-geo@1")

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