46 lines
1.6 KiB
JavaScript
46 lines
1.6 KiB
JavaScript
import sharp from "sharp";
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import path from "path";
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export default class AlphaComposite {
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async process(filename, maskFilename, extractedDir) {
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const image = sharp(path.join(extractedDir, filename))
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.removeAlpha()
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const imageMeta = await image.metadata()
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const imageBuffer = await image.toBuffer()
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const mask = await sharp(path.join(extractedDir, maskFilename))
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.extractChannel("blue")
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.resize(imageMeta.width, imageMeta.height)
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.toBuffer();
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return sharp(imageBuffer)
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.joinChannel(mask)
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.toBuffer()
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}
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async crop(buffer, rect) {
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const left = rect.y
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const top = rect.x
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const width = rect.h
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const height = rect.w
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const rotate = rect.rotate === 0 ? -90 : 0
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const newImage = await sharp(buffer).rotate(90).extract({ left: left, top: top, width: width, height: height }).resize(width, height).extract({ left: 0, top: 0, width: width, height: height }).toBuffer()
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return await sharp(newImage).rotate(rotate).toBuffer()
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}
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async toBuffer(filename, extractedDir) {
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const file = path.join(extractedDir, filename)
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const { data, info } = await sharp(file).raw().toBuffer({ resolveWithObject: true })
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const { width, height, channels } = info;
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const pixelArray = new Uint8ClampedArray(data.buffer);
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for (let i = 0; i < pixelArray.length; i += 4) {
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let alpha = pixelArray[i + 3] / 255;
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pixelArray[i + 0] = pixelArray[i + 0] * alpha
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pixelArray[i + 1] = pixelArray[i + 1] * alpha
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pixelArray[i + 2] = pixelArray[i + 2] * alpha
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}
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return await sharp(pixelArray, { raw: { width, height, channels } }).png().toBuffer();
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}
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}
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