mirror of
https://github.com/ConnectedHumber/Air-Quality-Web
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Starbeamrainbowlabs
b91794fa61
Plan: - Fetch SVG - Find + replace special marker with colour - Generate data URL (See btoa()) - Use it in a Marker in Leaflet
46 lines
1.2 KiB
JavaScript
46 lines
1.2 KiB
JavaScript
"use strict";
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function colourize(image, r, g, b) {
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let canvas = document.createElement("canvas"),
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context = canvas.getContext("2d");
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canvas.width = image.width;
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canvas.height = image.height;
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context.drawImage(image, 0, 0);
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let image_data = context.getImageData(
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0, 0,
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canvas.width, canvas.height
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),
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buf = new ArrayBuffer(image_data.data.length),
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view = new Uint32Array(buf),
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view8 = new Uint8ClampedArray(buf);
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console.log(`Canvas: ${canvas.width}x${canvas.height}, image data: ${image_data.width}x${image_data.height}`);
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let count = 0;
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for(let y = 0; y < image_data.height; y++) {
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for(let x = 0; x < image_data.width; x++) {
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let loc = y*image_data.width + x;
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//if(image_data.data[loc*4 + 3] == 0) continue
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view[loc] =
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(image_data.data[loc*4 + 3] << 24) | // Alpha
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((b+image_data.data[loc*4 + 2])/2 << 16) | // Blue
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((g+image_data.data[loc*4 + 1])/2 << 8) | // Green
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(r+image_data.data[loc*4])/2; // Red
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count++;
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}
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}
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console.log(`Changed ${count} / ${canvas.width*canvas.height} pixels`);
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image_data.data.set(view8);
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context.putImageData(image_data, 0, 0);
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return canvas.toDataURL();
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// let image_data = context.getImageData()
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}
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export default colourize;
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