38 lines
1.0 KiB
TypeScript
38 lines
1.0 KiB
TypeScript
import type { PixelImage } from './types';
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export function encodeBmpBytes(img: PixelImage): Uint8Array<ArrayBuffer> {
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const rowSize = Math.ceil((img.width * 3) / 4) * 4;
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const pixelArraySize = rowSize * img.height;
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const fileSize = 54 + pixelArraySize;
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const buf = new Uint8Array(fileSize);
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const view = new DataView(buf.buffer);
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buf[0] = 0x42;
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buf[1] = 0x4d;
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view.setUint32(2, fileSize, true);
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view.setUint32(10, 54, true);
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view.setUint32(14, 40, true);
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view.setInt32(18, img.width, true);
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view.setInt32(22, img.height, true);
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view.setUint16(26, 1, true);
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view.setUint16(28, 24, true);
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view.setUint32(30, 0, true);
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view.setUint32(34, pixelArraySize, true);
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view.setInt32(38, 2835, true);
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view.setInt32(42, 2835, true);
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for (let y = 0; y < img.height; y++) {
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const srcY = img.height - 1 - y;
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let off = 54 + y * rowSize;
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for (let x = 0; x < img.width; x++) {
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const i = (srcY * img.width + x) * 4;
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buf[off++] = img.data[i + 2];
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buf[off++] = img.data[i + 1];
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buf[off++] = img.data[i];
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}
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}
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return buf;
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}
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