44 lines
1.2 KiB
Plaintext
44 lines
1.2 KiB
Plaintext
import { readUInt16LE } from "./utils.js";
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const TYPE_ICON = 1;
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const SIZE_HEADER = 2 + 2 + 2;
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const SIZE_IMAGE_ENTRY = 1 + 1 + 1 + 1 + 2 + 2 + 4 + 4;
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function getSizeFromOffset(input, offset) {
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const value = input[offset];
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return value === 0 ? 256 : value;
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}
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function getImageSize(input, imageIndex) {
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const offset = SIZE_HEADER + imageIndex * SIZE_IMAGE_ENTRY;
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return {
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height: getSizeFromOffset(input, offset + 1),
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width: getSizeFromOffset(input, offset)
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};
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}
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const ICO = {
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validate(input) {
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const reserved = readUInt16LE(input, 0);
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const imageCount = readUInt16LE(input, 4);
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if (reserved !== 0 || imageCount === 0)
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return false;
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const imageType = readUInt16LE(input, 2);
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return imageType === TYPE_ICON;
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},
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calculate(input) {
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const nbImages = readUInt16LE(input, 4);
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const imageSize = getImageSize(input, 0);
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if (nbImages === 1)
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return imageSize;
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const imgs = [imageSize];
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for (let imageIndex = 1; imageIndex < nbImages; imageIndex += 1) {
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imgs.push(getImageSize(input, imageIndex));
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}
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return {
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height: imageSize.height,
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images: imgs,
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width: imageSize.width
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};
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}
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};
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export {
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ICO
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};
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