nodeGroup: d => d.id.split(/\W/)[0],

width,

format: (f => d => `${f(d)} Acres`)(d3.format(",.1~f")),

// Had to fork the built in Sankey Library so I could make the colors match the Land-Use classes

adjustNodeColor: (c,t)=>

{

switch (t.split(/[\W\n]/)[0])

{

case "Water":

return "#419bdf";

case "Trees":

return "#397d49";

case "Rangeland":

return "#e3e2c3";

case "Crops":

return "#e49635";

case "Built":

return "#c4281b";

case "Bare":

return "#a59b8f";

case "Snow":

return "#aaeafd";

case "Flooded":

return "#7a87c6";

}},

height: 300})

let result={};

console.log(map.getCenter());

console.log(map.getZoom());

console.log("starting analyze");

const NO_DATA =0; //255,255,255

const WATER=1; // 65,155,223

const TREES=2; // 57,125, 73

const FLOODED_VEGETATION=3; //122,135,198

const CROPS=4; //228,150, 53

const BUILT_AREA = 5; //196, 40, 27

const BARE_GROUND=6; //165,155,143

const SNOW_ICE=7; //168,235,255

const CLOUDS=8; // 97, 97, 97

const RANGELAND=9; //227,226,195

const FRIENDLY_NAMES = ["No Data","Water","Trees","Flooded Vegetation","Crops","Built Area","Bare Ground","Snow/Ice","Clouds","Rangeland"];

const SQM_PER_ACRE = 4046.86; //ugh, why no metric in this country

const WGS_EARTH_RADIUS = 6378137.0; // used to calculate areas

// ripped from the Leaflet-draw library because it wasn't happy being included here and is total ovekill

let geodesicArea = function (latLngs) {

var pointsCount = latLngs.length,

area = 0.0,

d2r = Math.PI / 180,

p1, p2;

if (pointsCount > 2) {

for (var i = 0; i < pointsCount; i++) {

p1 = latLngs[i];

p2 = latLngs[(i + 1) % pointsCount];

area += ((p2.lng - p1.lng) * d2r) *

(2 + Math.sin(p1.lat * d2r) + Math.sin(p2.lat * d2r));

}

area = area * (WGS_EARTH_RADIUS*WGS_EARTH_RADIUS) / 2.0;

}

return Math.abs(area);

}

// We can determine the use type entirely by the red pixels as each item in the symbology varies

function getUseType(redPixel)

{

switch (redPixel)

{

case 65: return WATER;

case 57: return TREES;

case 122: return FLOODED_VEGETATION;

case 228: return CROPS;

case 196: return BUILT_AREA;

case 165: return BARE_GROUND;

case 168: return SNOW_ICE;

case 97: return CLOUDS;

case 227: return RANGELAND;

}

return redPixel;

// console.log("Undefined r of "+ redPixel);

}

// This is a custom forked version of the LeafletImage library that will let me render a single layer

// instead of the map as it shows up on screen.

let complete=false;

let ls2017only = function(l){ return l.name=="2017";}

LeafletImage(map, ls2017only, function(err,canvas2017) {

let ls2021Only = function(l){ return l.name=="2021";}

LeafletImage(map, ls2021Only, function(err,canvas2021) {

var dimensions = map.getSize();

const image2017 = canvas2017.getContext("2d").getImageData(0,0,dimensions.x,dimensions.y);

const image2021 = canvas2021.getContext("2d").getImageData(0,0,dimensions.x,dimensions.y);

result.totalMapAreaSqM = geodesicArea(

[map.getBounds().getNorthWest(),

map.getBounds().getNorthEast(),

map.getBounds().getSouthEast(),

map.getBounds().getSouthWest() ]);

result.acresPerPixel = result.totalMapAreaSqM/ SQM_PER_ACRE / (dimensions.x * dimensions.y);

result.pixelsChangedDict=[];

result.totalPixels=0;

result.pixelsChanged=0;

for (let i = 0; i < image2017.data.length; i += 4)

{

result.totalPixels++;

let pixelUse2017 =getUseType(image2017.data[i]);

let pixelUse2021 =getUseType(image2021.data[i]);

if (pixelUse2017!=pixelUse2021)

{

result.pixelsChanged++;

}

if (!result.pixelsChangedDict[pixelUse2017 + "|" + pixelUse2021])

{

result.pixelsChangedDict[pixelUse2017 + "|" + pixelUse2021]=0;

}

result.pixelsChangedDict[pixelUse2017 + "|" + pixelUse2021]++;

}

result.sankey=[];

for (let src=0;src<FRIENDLY_NAMES.length;src++)

{

for (let dest=0;dest<FRIENDLY_NAMES.length;dest++)

{

if ((result.pixelsChangedDict[src + "|" + dest]) && result.pixelsChangedDict[src + "|" + dest]>1000)

{

result.sankey.push({source:FRIENDLY_NAMES[src] , target: FRIENDLY_NAMES[dest]+" ", value:(result.pixelsChangedDict[src + "|" + dest]*result.acresPerPixel) });

}

}

}

console.log("done analyzing");

complete=true;

console.log(result);

});

});

// THis is horribly hacky, but stops us returning until everything is loaded

while (!complete)

{

await new Promise(r => setTimeout(r, 100));

}

return result;

}

LeafletImage = require("https://cdn.jsdelivr.net/gh/grahamsz/leaflet-image-layers/leaflet-image.js?2")