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| import Map from 'ol/Map.js';
import RasterSource from 'ol/source/Raster.js';
import View from 'ol/View.js';
import XYZ from 'ol/source/XYZ.js';
import {Image as ImageLayer, Tile as TileLayer} from 'ol/layer.js';
import {fromLonLat} from 'ol/proj.js';
function growRegion(inputs, data) {
const image = inputs[0];
let seed = data.pixel;
const delta = parseInt(data.delta);
if (!seed) {
return image;
}
seed = seed.map(Math.round);
const width = image.width;
const height = image.height;
const inputData = image.data;
const outputData = new Uint8ClampedArray(inputData);
const seedIdx = (seed[1] * width + seed[0]) * 4;
const seedR = inputData[seedIdx];
const seedG = inputData[seedIdx + 1];
const seedB = inputData[seedIdx + 2];
let edge = [seed];
while (edge.length) {
const newedge = [];
for (let i = 0, ii = edge.length; i < ii; i++) {
const next = next4Edges(edge[i]);
for (let j = 0, jj = next.length; j < jj; j++) {
const s = next[j][0];
const t = next[j][1];
if (s >= 0 && s < width && t >= 0 && t < height) {
const ci = (t * width + s) * 4;
const cr = inputData[ci];
const cg = inputData[ci + 1];
const cb = inputData[ci + 2];
const ca = inputData[ci + 3];
if (ca === 0) {
continue;
}
if (
Math.abs(seedR - cr) < delta &&
Math.abs(seedG - cg) < delta &&
Math.abs(seedB - cb) < delta
) {
outputData[ci] = 255;
outputData[ci + 1] = 0;
outputData[ci + 2] = 0;
outputData[ci + 3] = 255;
newedge.push([s, t]);
}
inputData[ci + 3] = 0;
}
}
}
edge = newedge;
}
return {data: outputData, width: width, height: height};
}
function next4Edges(edge) {
const x = edge[0];
const y = edge[1];
return [
[x + 1, y],
[x - 1, y],
[x, y + 1],
[x, y - 1],
];
}
const key = 'Get your own API key at https://www.maptiler.com/cloud/';
const attributions =
'<a href="https://www.maptiler.com/copyright/" target="_blank">© MapTiler</a> ' +
'<a href="https://www.openstreetmap.org/copyright" target="_blank">© OpenStreetMap contributors</a>';
const imagery = new TileLayer({
source: new XYZ({
attributions: attributions,
url: 'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
maxZoom: 20,
crossOrigin: '',
}),
});
const raster = new RasterSource({
sources: [imagery.getSource()],
operationType: 'image',
operation: growRegion,
lib: {
next4Edges: next4Edges,
},
});
const rasterImage = new ImageLayer({
opacity: 0.7,
source: raster,
});
const map = new Map({
layers: [imagery, rasterImage],
target: 'map',
view: new View({
center: fromLonLat([-119.07, 47.65]),
zoom: 11,
}),
});
let coordinate;
map.on('click', function (event) {
coordinate = event.coordinate;
raster.changed();
});
const thresholdControl = document.getElementById('threshold');
raster.on('beforeoperations', function (event) {
const data = event.data;
data.delta = thresholdControl.value;
if (coordinate) {
data.pixel = map.getPixelFromCoordinate(coordinate);
}
});
function updateControlValue() {
document.getElementById('threshold-value').innerText = thresholdControl.value;
}
updateControlValue();
thresholdControl.addEventListener('input', function () {
updateControlValue();
raster.changed();
});
|
)
