53 lines
1.5 KiB
Text
53 lines
1.5 KiB
Text
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window.addEventListener("load", () => main());
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const main = () => {
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for (const item of document.getElementsByTagName("img")) {
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if (!item.src.startsWith("data:image/svg+xml;base64,")) {
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// Exclude image who aren't SVG and base64 encoded
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break;
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}
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/** Convert to grayscale */
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const colorToGrayscale = (color) => {
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return 0.3 * color.r + 0.59 * color.g + 0.11 * color.b;
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};
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/** Extract color using canvas2d */
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const extractColors = (image) => {
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const canvas = document.createElement("canvas");
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canvas.width = image.width;
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canvas.height = image.height;
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const ctx = canvas.getContext("2d");
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ctx.drawImage(image, 0, 0);
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const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
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const pixelData = imageData.data;
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const colors = [];
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for (let i = 0; i < pixelData.length; i += 4) {
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if (pixelData[i + 3] > 0) {
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colors.push({
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r: pixelData[i],
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g: pixelData[i + 1],
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b: pixelData[i + 2],
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});
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}
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}
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return colors;
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};
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// Extract colors
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const colors = extractColors(item);
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// Calculate the average grayscale value
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const grayscaleValues = colors.map(colorToGrayscale);
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const totalGrayscale = grayscaleValues.reduce((acc, val) => acc + val, 0);
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const averageGrayscale = totalGrayscale / grayscaleValues.length;
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console.log(averageGrayscale);
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if (averageGrayscale < 128) {
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item.style = "filter: invert(1);";
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}
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}
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};
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