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58 lines
2.4 KiB
JavaScript
58 lines
2.4 KiB
JavaScript
import { removeDopplerRadarImageNoise } from './radar-utils.mjs';
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import { RADAR_FULL_SIZE, RADAR_FINAL_SIZE } from './radar-constants.mjs';
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onmessage = async (e) => {
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const {
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url, RADAR_HOST, OVERRIDES, radarSourceXY,
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} = e.data;
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// get the image
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const modifiedRadarUrl = OVERRIDES.RADAR_HOST ? url.replace(RADAR_HOST, OVERRIDES.RADAR_HOST) : url;
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const radarResponsePromise = fetch(modifiedRadarUrl);
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// calculate offsets and sizes
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const radarSource = {
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width: 240,
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height: 163,
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x: Math.round(radarSourceXY.x / 2),
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y: Math.round(radarSourceXY.y / 2),
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};
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// create radar context for manipulation
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const radarCanvas = new OffscreenCanvas(RADAR_FULL_SIZE.width, RADAR_FULL_SIZE.height);
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const radarContext = radarCanvas.getContext('2d');
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radarContext.imageSmoothingEnabled = false;
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// test response
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const radarResponse = await radarResponsePromise;
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if (!radarResponse.ok) throw new Error(`Unable to fetch radar error ${radarResponse.status} ${radarResponse.statusText} from ${radarResponse.url}`);
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// get the blob
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const radarImgBlob = await radarResponse.blob();
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// assign to an html image element
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const radarImgElement = await createImageBitmap(radarImgBlob);
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// draw the entire image
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radarContext.clearRect(0, 0, RADAR_FULL_SIZE.width, RADAR_FULL_SIZE.height);
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radarContext.drawImage(radarImgElement, 0, 0, RADAR_FULL_SIZE.width, RADAR_FULL_SIZE.height);
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// crop the radar image without scaling
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const croppedRadarCanvas = new OffscreenCanvas(radarSource.width, radarSource.height);
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const croppedRadarContext = croppedRadarCanvas.getContext('2d');
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croppedRadarContext.imageSmoothingEnabled = false;
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croppedRadarContext.drawImage(radarCanvas, radarSource.x, radarSource.y, croppedRadarCanvas.width, croppedRadarCanvas.height, 0, 0, croppedRadarCanvas.width, croppedRadarCanvas.height);
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// clean the image
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removeDopplerRadarImageNoise(croppedRadarContext);
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// stretch the radar image
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const stretchCanvas = new OffscreenCanvas(RADAR_FINAL_SIZE.width, RADAR_FINAL_SIZE.height);
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const stretchContext = stretchCanvas.getContext('2d', { willReadFrequently: true });
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stretchContext.imageSmoothingEnabled = false;
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stretchContext.drawImage(croppedRadarCanvas, 0, 0, radarSource.width, radarSource.height, 0, 0, RADAR_FINAL_SIZE.width, RADAR_FINAL_SIZE.height);
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const stretchedRadar = stretchCanvas.transferToImageBitmap();
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postMessage(stretchedRadar, [stretchedRadar]);
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};
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