Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 42x 40x 40x 42x 42x 42x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 2x 2x 2x 2x 2x 2x 2x 4x 4x 4x 4x 3x 3x 1x 1x 1x 2x 2x 2x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 72x 72x 72x 1x 1x 1x 1x 1x 1x 1x 1x | /**
* Calculate the row/column coordinates of the center module of each alignment pattern
* for the specified QR Code version.
*
* The alignment patterns are positioned symmetrically on either side of the diagonal
* running from the top left corner of the symbol to the bottom right corner.
*
* Since positions are symmetrical only half of the coordinates are returned.
* Each item of the array will represent in turn the x and y coordinate.
* @see {@link getPositions}
* @param {number} version - QR Code version
* @returns {number[]} Array of coordinate
*/
export function calculateCoordinates (version) {
if (version === 1) return []
const intervals = Math.floor(version / 7) + 1
const distance = 4 * version + 4 // between first and last pattern
const step = version === 32 ? 26 : Math.ceil(distance / intervals / 2) * 2
return [6, ...Array.from({ length: intervals }, (_, index) => distance + 6 - (intervals - 1 - index) * step)]
}
/**
* Returns an array containing the positions of each alignment pattern.
* Each array's element represent the center point of the pattern as (x, y) coordinates
*
* Coordinates are calculated expanding the row/column coordinates returned by {@link calculateCoordinates}
* and filtering out the items that overlaps with finder pattern
* @param {number} version - QR Code version
* @returns {PatternPositions} list of pattern positions
*/
export function calculatePositions (version) {
/** @type {Point[]} */
const coords = []
const pos = calculateCoordinates(version)
const posLength = pos.length
for (let i = 0; i < posLength; i++) {
for (let j = 0; j < posLength; j++) {
// Skip if position is occupied by finder patterns
if ((i === 0 && j === 0) || // top-left
(i === 0 && j === posLength - 1) || // bottom-left
(i === posLength - 1 && j === 0)) { // top-right
continue
}
coords.push(Object.freeze([pos[i], pos[j]]))
}
}
return Object.freeze(coords)
}
/**
* Used to memoize getPatternPosition calls
* @type {PatternPositions[]}
*/
const positionsMemo = []
/**
* Returns an array containing the positions of each alignment pattern.
* Each array's element represent the center point of the pattern as (x, y) coordinates
* @param {number} version - QR code version
* @returns {PatternPositions} list of pattern positions
*/
export function getPatternPositions (version) {
if (!Number.isInteger(version) || version < 1 || version > 40) {
throw Error(`invalid pattern @ version:${version}'`)
}
return (positionsMemo[version - 1] ??= calculatePositions(version))
}
/**
* @typedef {Readonly<[number, number]>} Point
*/
/**
* @typedef {Readonly<Point[]>} PatternPositions
*/
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