0f8399ec88
Replace CDN React/ReactDOM/Babel with local libs; remove Babel and inline scripts Build Tailwind locally, add safelist; switch to assets/tailwind.css Self-host Font Awesome and Inter (CSS + woff2); remove external font CDNs Implement strict CSP (no unsafe-inline/eval; scripts/styles/fonts from self) Extract inline handlers; move PWA scripts to external files Add local QR code generation (qrcode lib) and remove api.qrserver.com Improve SessionTypeSelector visual selection (highlighted background and ring) Keep PWA working with service worker and offline assets Refs: CSP hardening, offline-first, no external dependencies
84 lines
2.9 KiB
JavaScript
84 lines
2.9 KiB
JavaScript
/**
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* Alignment pattern are fixed reference pattern in defined positions
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* in a matrix symbology, which enables the decode software to re-synchronise
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* the coordinate mapping of the image modules in the event of moderate amounts
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* of distortion of the image.
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*
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* Alignment patterns are present only in QR Code symbols of version 2 or larger
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* and their number depends on the symbol version.
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*/
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const getSymbolSize = require('./utils').getSymbolSize
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/**
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* Calculate the row/column coordinates of the center module of each alignment pattern
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* for the specified QR Code version.
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*
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* The alignment patterns are positioned symmetrically on either side of the diagonal
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* running from the top left corner of the symbol to the bottom right corner.
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*
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* Since positions are simmetrical only half of the coordinates are returned.
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* Each item of the array will represent in turn the x and y coordinate.
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* @see {@link getPositions}
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*
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* @param {Number} version QR Code version
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* @return {Array} Array of coordinate
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*/
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exports.getRowColCoords = function getRowColCoords (version) {
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if (version === 1) return []
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const posCount = Math.floor(version / 7) + 2
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const size = getSymbolSize(version)
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const intervals = size === 145 ? 26 : Math.ceil((size - 13) / (2 * posCount - 2)) * 2
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const positions = [size - 7] // Last coord is always (size - 7)
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for (let i = 1; i < posCount - 1; i++) {
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positions[i] = positions[i - 1] - intervals
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}
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positions.push(6) // First coord is always 6
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return positions.reverse()
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}
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/**
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* Returns an array containing the positions of each alignment pattern.
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* Each array's element represent the center point of the pattern as (x, y) coordinates
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*
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* Coordinates are calculated expanding the row/column coordinates returned by {@link getRowColCoords}
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* and filtering out the items that overlaps with finder pattern
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*
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* @example
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* For a Version 7 symbol {@link getRowColCoords} returns values 6, 22 and 38.
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* The alignment patterns, therefore, are to be centered on (row, column)
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* positions (6,22), (22,6), (22,22), (22,38), (38,22), (38,38).
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* Note that the coordinates (6,6), (6,38), (38,6) are occupied by finder patterns
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* and are not therefore used for alignment patterns.
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*
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* let pos = getPositions(7)
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* // [[6,22], [22,6], [22,22], [22,38], [38,22], [38,38]]
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*
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* @param {Number} version QR Code version
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* @return {Array} Array of coordinates
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*/
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exports.getPositions = function getPositions (version) {
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const coords = []
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const pos = exports.getRowColCoords(version)
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const posLength = pos.length
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for (let i = 0; i < posLength; i++) {
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for (let j = 0; j < posLength; j++) {
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// Skip if position is occupied by finder patterns
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if ((i === 0 && j === 0) || // top-left
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(i === 0 && j === posLength - 1) || // bottom-left
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(i === posLength - 1 && j === 0)) { // top-right
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continue
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}
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coords.push([pos[i], pos[j]])
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}
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}
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return coords
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}
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