@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
157 lines (156 loc) • 5.65 kB
JavaScript
import Arrays from '../../util/Arrays';
/**
* Symbol Character Placement Program. Adapted from Annex M.1 in ISO/IEC 16022:2000(E).
*/
class DefaultPlacement {
/**
* Main constructor
*
* @param codewords the codewords to place
* @param numcols the number of columns
* @param numrows the number of rows
*/
constructor(codewords, numcols, numrows) {
this.codewords = codewords;
this.numcols = numcols;
this.numrows = numrows;
this.bits = new Uint8Array(numcols * numrows);
Arrays.fill(this.bits, 2); // Initialize with "not set" value
}
getNumrows() {
return this.numrows;
}
getNumcols() {
return this.numcols;
}
getBits() {
return this.bits;
}
getBit(col, row) {
return this.bits[row * this.numcols + col] === 1;
}
setBit(col, row, bit) {
this.bits[row * this.numcols + col] = bit ? 1 : 0;
}
noBit(col, row) {
return this.bits[row * this.numcols + col] === 2;
}
place() {
let pos = 0;
let row = 4;
let col = 0;
do {
// repeatedly first check for one of the special corner cases, then...
if (row === this.numrows && col === 0) {
this.corner1(pos++);
}
if (row === this.numrows - 2 && col === 0 && this.numcols % 4 !== 0) {
this.corner2(pos++);
}
if (row === this.numrows - 2 && col === 0 && this.numcols % 8 === 4) {
this.corner3(pos++);
}
if (row === this.numrows + 4 && col === 2 && this.numcols % 8 === 0) {
this.corner4(pos++);
}
// sweep upward diagonally, inserting successive characters...
do {
if (row < this.numrows && col >= 0 && this.noBit(col, row)) {
this.utah(row, col, pos++);
}
row -= 2;
col += 2;
} while (row >= 0 && col < this.numcols);
row++;
col += 3;
// and then sweep downward diagonally, inserting successive characters, ...
do {
if (row >= 0 && col < this.numcols && this.noBit(col, row)) {
this.utah(row, col, pos++);
}
row += 2;
col -= 2;
} while (row < this.numrows && col >= 0);
row += 3;
col++;
// ...until the entire array is scanned
} while (row < this.numrows || col < this.numcols);
// Lastly, if the lower right-hand corner is untouched, fill in fixed pattern
if (this.noBit(this.numcols - 1, this.numrows - 1)) {
this.setBit(this.numcols - 1, this.numrows - 1, true);
this.setBit(this.numcols - 2, this.numrows - 2, true);
}
}
module(row, col, pos, bit) {
if (row < 0) {
row += this.numrows;
col += 4 - ((this.numrows + 4) % 8);
}
if (col < 0) {
col += this.numcols;
row += 4 - ((this.numcols + 4) % 8);
}
// Note the conversion:
let v = this.codewords.charCodeAt(pos);
v &= 1 << (8 - bit);
this.setBit(col, row, v !== 0);
}
/**
* Places the 8 bits of a utah-shaped symbol character in ECC200.
*
* @param row the row
* @param col the column
* @param pos character position
*/
utah(row, col, pos) {
this.module(row - 2, col - 2, pos, 1);
this.module(row - 2, col - 1, pos, 2);
this.module(row - 1, col - 2, pos, 3);
this.module(row - 1, col - 1, pos, 4);
this.module(row - 1, col, pos, 5);
this.module(row, col - 2, pos, 6);
this.module(row, col - 1, pos, 7);
this.module(row, col, pos, 8);
}
corner1(pos) {
this.module(this.numrows - 1, 0, pos, 1);
this.module(this.numrows - 1, 1, pos, 2);
this.module(this.numrows - 1, 2, pos, 3);
this.module(0, this.numcols - 2, pos, 4);
this.module(0, this.numcols - 1, pos, 5);
this.module(1, this.numcols - 1, pos, 6);
this.module(2, this.numcols - 1, pos, 7);
this.module(3, this.numcols - 1, pos, 8);
}
corner2(pos) {
this.module(this.numrows - 3, 0, pos, 1);
this.module(this.numrows - 2, 0, pos, 2);
this.module(this.numrows - 1, 0, pos, 3);
this.module(0, this.numcols - 4, pos, 4);
this.module(0, this.numcols - 3, pos, 5);
this.module(0, this.numcols - 2, pos, 6);
this.module(0, this.numcols - 1, pos, 7);
this.module(1, this.numcols - 1, pos, 8);
}
corner3(pos) {
this.module(this.numrows - 3, 0, pos, 1);
this.module(this.numrows - 2, 0, pos, 2);
this.module(this.numrows - 1, 0, pos, 3);
this.module(0, this.numcols - 2, pos, 4);
this.module(0, this.numcols - 1, pos, 5);
this.module(1, this.numcols - 1, pos, 6);
this.module(2, this.numcols - 1, pos, 7);
this.module(3, this.numcols - 1, pos, 8);
}
corner4(pos) {
this.module(this.numrows - 1, 0, pos, 1);
this.module(this.numrows - 1, this.numcols - 1, pos, 2);
this.module(0, this.numcols - 3, pos, 3);
this.module(0, this.numcols - 2, pos, 4);
this.module(0, this.numcols - 1, pos, 5);
this.module(1, this.numcols - 3, pos, 6);
this.module(1, this.numcols - 2, pos, 7);
this.module(1, this.numcols - 1, pos, 8);
}
}
export default DefaultPlacement;