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272 lines
10 KiB
272 lines
10 KiB
/*
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* QR Code generator library (Java)
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*
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* Copyright (c) Project Nayuki
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* https://www.nayuki.io/page/qr-code-generator-library
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*
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* (MIT License)
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* - The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* - The Software is provided "as is", without warranty of any kind, express or
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* implied, including but not limited to the warranties of merchantability,
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* fitness for a particular purpose and noninfringement. In no event shall the
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* authors or copyright holders be liable for any claim, damages or other
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* liability, whether in an action of contract, tort or otherwise, arising from,
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* out of or in connection with the Software or the use or other dealings in the
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* Software.
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*/
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package io.nayuki.qrcodegen;
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import java.nio.charset.StandardCharsets;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Objects;
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import java.util.regex.Pattern;
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/**
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* Represents a character string to be encoded in a QR Code symbol. Each segment has
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* a mode, and a sequence of characters that is already encoded as a sequence of bits.
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* Instances of this class are immutable.
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* <p>This segment class imposes no length restrictions, but QR Codes have restrictions.
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* Even in the most favorable conditions, a QR Code can only hold 7089 characters of data.
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* Any segment longer than this is meaningless for the purpose of generating QR Codes.</p>
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*/
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public final class QrSegment {
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/*---- Static factory functions ----*/
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/**
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* Returns a segment representing the specified binary data encoded in byte mode.
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* @param data the binary data
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* @return a segment containing the data
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* @throws NullPointerException if the array is {@code null}
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*/
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public static QrSegment makeBytes(byte[] data) {
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Objects.requireNonNull(data);
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return new QrSegment(Mode.BYTE, data.length, data, data.length * 8);
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}
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/**
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* Returns a segment representing the specified string of decimal digits encoded in numeric mode.
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* @param digits a string consisting of digits from 0 to 9
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* @return a segment containing the data
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* @throws NullPointerException if the string is {@code null}
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* @throws IllegalArgumentException if the string contains non-digit characters
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*/
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public static QrSegment makeNumeric(String digits) {
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Objects.requireNonNull(digits);
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if (!NUMERIC_REGEX.matcher(digits).matches())
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throw new IllegalArgumentException("String contains non-numeric characters");
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BitBuffer bb = new BitBuffer();
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int i;
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for (i = 0; i + 3 <= digits.length(); i += 3) // Process groups of 3
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bb.appendBits(Integer.parseInt(digits.substring(i, i + 3)), 10);
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int rem = digits.length() - i;
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if (rem > 0) // 1 or 2 digits remaining
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bb.appendBits(Integer.parseInt(digits.substring(i)), rem * 3 + 1);
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return new QrSegment(Mode.NUMERIC, digits.length(), bb.getBytes(), bb.bitLength());
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}
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/**
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* Returns a segment representing the specified text string encoded in alphanumeric mode. The characters allowed are:
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* 0 to 9, A to Z (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
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* @param text a string of text, with only certain characters allowed
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* @return a segment containing the data
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* @throws NullPointerException if the string is {@code null}
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* @throws IllegalArgumentException if the string contains non-encodable characters
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*/
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public static QrSegment makeAlphanumeric(String text) {
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Objects.requireNonNull(text);
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if (!ALPHANUMERIC_REGEX.matcher(text).matches())
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throw new IllegalArgumentException("String contains unencodable characters in alphanumeric mode");
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BitBuffer bb = new BitBuffer();
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int i;
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for (i = 0; i + 2 <= text.length(); i += 2) { // Process groups of 2
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int temp = ALPHANUMERIC_ENCODING_TABLE[text.charAt(i) - ' '] * 45;
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temp += ALPHANUMERIC_ENCODING_TABLE[text.charAt(i + 1) - ' '];
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bb.appendBits(temp, 11);
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}
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if (i < text.length()) // 1 character remaining
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bb.appendBits(ALPHANUMERIC_ENCODING_TABLE[text.charAt(i) - ' '], 6);
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return new QrSegment(Mode.ALPHANUMERIC, text.length(), bb.getBytes(), bb.bitLength());
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}
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/**
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* Returns a new mutable list of zero or more segments to represent the specified Unicode text string.
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* The result may use various segment modes and switch modes to optimize the length of the bit stream.
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* @param text the text to be encoded, which can be any Unicode string
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* @return a list of segments containing the text
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* @throws NullPointerException if the text is {@code null}
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*/
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public static List<QrSegment> makeSegments(String text) {
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Objects.requireNonNull(text);
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// Select the most efficient segment encoding automatically
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List<QrSegment> result = new ArrayList<>();
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if (text.equals(""))
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return result;
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else if (NUMERIC_REGEX.matcher(text).matches())
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result.add(makeNumeric(text));
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else if (ALPHANUMERIC_REGEX.matcher(text).matches())
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result.add(makeAlphanumeric(text));
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else
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result.add(makeBytes(text.getBytes(StandardCharsets.UTF_8)));
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return result;
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}
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/*---- Instance fields ----*/
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/** The mode indicator for this segment. Never {@code null}. */
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public final Mode mode;
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/** The length of this segment's unencoded data, measured in characters. Always zero or positive. */
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public final int numChars;
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/** The bits of this segment packed into a byte array in big endian. Accessed through {@link getByte(int)}. Not {@code null}. */
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private final byte[] data;
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/** The length of this segment's encoded data, measured in bits. Satisfies 0 ≤ {@code bitLength} ≤ {@code data.length} × 8. */
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public final int bitLength;
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/*---- Constructor ----*/
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/**
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* Creates a new QR Code data segment with the specified parameters and data.
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* @param md the mode, which is not {@code null}
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* @param numCh the data length in characters, which is non-negative
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* @param bitLen the data length in bits, which is non-negative
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* @param b the bits packed into bytes, which is not {@code null}
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* @throws NullPointerException if the mode or array is {@code null}
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* @throws IllegalArgumentException if the character count or bit length are negative or invalid
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*/
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public QrSegment(Mode md, int numCh, byte[] b, int bitLen) {
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Objects.requireNonNull(md);
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Objects.requireNonNull(b);
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if (numCh < 0 || bitLen < 0 || bitLen > b.length * 8L)
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throw new IllegalArgumentException("Invalid value");
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mode = md;
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numChars = numCh;
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data = Arrays.copyOf(b, (bitLen + 7) / 8); // Trim to precise length and also make defensive copy
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bitLength = bitLen;
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}
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/*---- Method ----*/
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/**
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* Returns the data byte at the specified index.
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* @param index the index to retrieve from, satisfying 0 ≤ {@code index} < ceil({@code bitLength} ÷ 8)
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* @return the data byte at the specified index
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* @throws IndexOutOfBoundsException if the index is out of bounds
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*/
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public byte getByte(int index) {
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if (index < 0 || index > data.length)
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throw new IndexOutOfBoundsException();
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return data[index];
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}
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// Package-private helper function.
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static int getTotalBits(List<QrSegment> segs, int version) {
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Objects.requireNonNull(segs);
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if (version < 1 || version > 40)
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throw new IllegalArgumentException("Version number out of range");
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int result = 0;
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for (QrSegment seg : segs) {
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Objects.requireNonNull(seg);
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int ccbits = seg.mode.numCharCountBits(version);
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// Fail if segment length value doesn't fit in the length field's bit-width
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if (seg.numChars >= (1 << ccbits))
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return -1;
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result += 4 + ccbits + seg.bitLength;
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}
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return result;
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}
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/*---- Constants ----*/
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/** Can test whether a string is encodable in numeric mode (such as by using {@link #makeNumeric(String)}). */
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public static final Pattern NUMERIC_REGEX = Pattern.compile("[0-9]*");
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/** Can test whether a string is encodable in alphanumeric mode (such as by using {@link #makeAlphanumeric(String)}). */
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public static final Pattern ALPHANUMERIC_REGEX = Pattern.compile("[A-Z0-9 $%*+./:-]*");
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/** Maps shifted ASCII codes to alphanumeric mode character codes. */
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private static final byte[] ALPHANUMERIC_ENCODING_TABLE = {
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// SP, !, ", #, $, %, &, ', (, ), *, +, ,, -, ., /, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, :, ;, <, =, >, ?, @, // ASCII codes 32 to 64
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36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 44, -1, -1, -1, -1, -1, -1, // Array indices 0 to 32
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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, // Array indices 33 to 58
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// A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, // ASCII codes 65 to 90
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};
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/*---- Public helper enumeration ----*/
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/**
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* The mode field of a segment. Immutable. Provides methods to retrieve closely related values.
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*/
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public enum Mode {
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/*-- Constants --*/
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NUMERIC (0x1, 10, 12, 14),
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ALPHANUMERIC(0x2, 9, 11, 13),
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BYTE (0x4, 8, 16, 16),
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KANJI (0x8, 8, 10, 12);
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/*-- Fields --*/
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/** An unsigned 4-bit integer value (range 0 to 15) representing the mode indicator bits for this mode object. */
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final int modeBits;
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private final int[] numBitsCharCount;
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/*-- Constructor --*/
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private Mode(int mode, int... ccbits) {
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this.modeBits = mode;
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numBitsCharCount = ccbits;
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}
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/*-- Method --*/
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/**
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* Returns the bit width of the segment character count field for this mode object at the specified version number.
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* @param ver the version number, which is between 1 to 40, inclusive
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* @return the number of bits for the character count, which is between 8 to 16, inclusive
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* @throws IllegalArgumentException if the version number is out of range
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*/
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int numCharCountBits(int ver) {
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if ( 1 <= ver && ver <= 9) return numBitsCharCount[0];
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else if (10 <= ver && ver <= 26) return numBitsCharCount[1];
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else if (27 <= ver && ver <= 40) return numBitsCharCount[2];
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else throw new IllegalArgumentException("Version number out of range");
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}
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}
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}
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