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339 lines
12 KiB
339 lines
12 KiB
/*
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* Fast QR Code generator library
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*
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* Copyright (c) Project Nayuki. (MIT License)
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* https://www.nayuki.io/page/fast-qr-code-generator-library
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*
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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.fastqrcodegen;
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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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/**
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* A segment of character/binary/control data in a QR Code symbol.
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* Instances of this class are immutable.
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* <p>The mid-level way to create a segment is to take the payload data and call a
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* static factory function such as {@link QrSegment#makeNumeric(String)}. The low-level
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* way to create a segment is to custom-make the bit buffer and call the {@link
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* QrSegment#QrSegment(Mode,int,int[],int) constructor} with appropriate values.</p>
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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.
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* This class can represent kanji mode segments, but provides no help in encoding them
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* - see {@link QrSegmentAdvanced} for full kanji support.</p>
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*/
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public final class QrSegment {
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/*---- Static factory functions (mid level) ----*/
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/**
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* Returns a segment representing the specified binary data
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* encoded in byte mode. All input byte arrays are acceptable.
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* <p>Any text string can be converted to UTF-8 bytes ({@code
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* s.getBytes(StandardCharsets.UTF_8)}) and encoded as a byte mode segment.</p>
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* @param data the binary data (not {@code null})
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* @return a segment (not {@code null}) 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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if (data.length * 8L > Integer.MAX_VALUE)
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throw new IllegalArgumentException("Data too long");
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int[] bits = new int[(data.length + 3) / 4];
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for (int i = 0; i < data.length; i++)
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bits[i >>> 2] |= (data[i] & 0xFF) << (~i << 3);
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return new QrSegment(Mode.BYTE, data.length, bits, 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 the text (not {@code null}), with only digits from 0 to 9 allowed
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* @return a segment (not {@code null}) containing the text
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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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BitBuffer bb = new BitBuffer();
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int accumData = 0;
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int accumCount = 0;
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for (int i = 0; i < digits.length(); i++) {
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char c = digits.charAt(i);
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if (c < '0' || c > '9')
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throw new IllegalArgumentException("String contains non-numeric characters");
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accumData = accumData * 10 + (c - '0');
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accumCount++;
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if (accumCount == 3) {
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bb.appendBits(accumData, 10);
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accumData = 0;
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accumCount = 0;
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}
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}
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if (accumCount > 0) // 1 or 2 digits remaining
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bb.appendBits(accumData, accumCount * 3 + 1);
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return new QrSegment(Mode.NUMERIC, digits.length(), bb.data, 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.
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* The characters allowed are: 0 to 9, A to Z (uppercase only), space,
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* dollar, percent, asterisk, plus, hyphen, period, slash, colon.
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* @param text the text (not {@code null}), with only certain characters allowed
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* @return a segment (not {@code null}) containing the text
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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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BitBuffer bb = new BitBuffer();
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int accumData = 0;
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int accumCount = 0;
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for (int i = 0; i < text.length(); i++) {
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char c = text.charAt(i);
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if (c >= ALPHANUMERIC_MAP.length || ALPHANUMERIC_MAP[c] == -1)
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throw new IllegalArgumentException("String contains unencodable characters in alphanumeric mode");
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accumData = accumData * 45 + ALPHANUMERIC_MAP[c];
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accumCount++;
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if (accumCount == 2) {
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bb.appendBits(accumData, 11);
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accumData = 0;
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accumCount = 0;
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}
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}
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if (accumCount > 0) // 1 character remaining
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bb.appendBits(accumData, 6);
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return new QrSegment(Mode.ALPHANUMERIC, text.length(), bb.data, bb.bitLength);
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}
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/**
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* Returns a 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 new mutable list (not {@code null}) of segments (not {@code null}) 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("")); // Leave result empty
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else if (isNumeric(text))
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result.add(makeNumeric(text));
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else if (isAlphanumeric(text))
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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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/**
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* Returns a segment representing an Extended Channel Interpretation
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* (ECI) designator with the specified assignment value.
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* @param assignVal the ECI assignment number (see the AIM ECI specification)
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* @return a segment (not {@code null}) containing the data
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* @throws IllegalArgumentException if the value is outside the range [0, 10<sup>6</sup>)
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*/
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public static QrSegment makeEci(int assignVal) {
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BitBuffer bb = new BitBuffer();
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if (assignVal < 0)
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throw new IllegalArgumentException("ECI assignment value out of range");
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else if (assignVal < (1 << 7))
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bb.appendBits(assignVal, 8);
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else if (assignVal < (1 << 14)) {
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bb.appendBits(2, 2);
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bb.appendBits(assignVal, 14);
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} else if (assignVal < 1_000_000) {
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bb.appendBits(6, 3);
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bb.appendBits(assignVal, 21);
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} else
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throw new IllegalArgumentException("ECI assignment value out of range");
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return new QrSegment(Mode.ECI, 0, bb.data, bb.bitLength);
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}
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/**
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* Tests whether the specified string can be encoded as a segment in numeric mode.
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* A string is encodable iff each character is in the range 0 to 9.
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* @param text the string to test for encodability (not {@code null})
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* @return {@code true} iff each character is in the range 0 to 9.
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* @throws NullPointerException if the string is {@code null}
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* @see #makeNumeric(String)
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*/
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public static boolean isNumeric(String text) {
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for (int i = 0; i < text.length(); i++) {
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char c = text.charAt(i);
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if (c < '0' || c > '9')
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return false;
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}
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return true;
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}
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/**
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* Tests whether the specified string can be encoded as a segment in alphanumeric mode.
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* A string is encodable iff each character is in the following set: 0 to 9, A to Z
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* (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
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* @param text the string to test for encodability (not {@code null})
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* @return {@code true} iff each character is in the alphanumeric mode character set
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* @throws NullPointerException if the string is {@code null}
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* @see #makeAlphanumeric(String)
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*/
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public static boolean isAlphanumeric(String text) {
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for (int i = 0; i < text.length(); i++) {
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char c = text.charAt(i);
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if (c >= ALPHANUMERIC_MAP.length || ALPHANUMERIC_MAP[c] == -1)
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return false;
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}
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return true;
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}
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/*---- Instance fields ----*/
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/** The mode indicator of this segment. Not {@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 for
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* numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
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* Always zero or positive. Not the same as the data's bit length. */
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public final int numChars;
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// The data bits of this segment. Not null.
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final int[] data;
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// Requires 0 <= bitLength <= data.length * 32.
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final int bitLength;
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/*---- Constructor (low level) ----*/
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/**
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* Constructs a QR Code segment with the specified attributes and data.
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* The character count (numCh) must agree with the mode and the bit buffer length,
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* but the constraint isn't checked. The specified bit buffer is cloned and stored.
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* @param md the mode (not {@code null})
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* @param numCh the data length in characters or bytes, which is non-negative
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* @param data the data bits (not {@code null})
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* @param bitLen the number of valid prefix bits in the data array
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* @throws NullPointerException if the mode or data is {@code null}
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* @throws IllegalArgumentException if the character count is negative
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*/
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public QrSegment(Mode md, int numCh, int[] data, int bitLen) {
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mode = Objects.requireNonNull(md);
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this.data = Objects.requireNonNull(data);
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if (numCh < 0 || bitLen < 0 || bitLen > data.length * 32L)
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throw new IllegalArgumentException("Invalid value");
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numChars = numCh;
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bitLength = bitLen;
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}
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// Calculates the number of bits needed to encode the given segments at the given version.
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// Returns a non-negative number if successful. Otherwise returns -1 if a segment has too
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// many characters to fit its length field, or the total bits exceeds Integer.MAX_VALUE.
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static int getTotalBits(List<QrSegment> segs, int version) {
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Objects.requireNonNull(segs);
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long 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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if (seg.numChars >= (1 << ccbits))
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return -1; // The segment's length doesn't fit the field's bit width
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result += 4L + ccbits + seg.bitLength;
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if (result > Integer.MAX_VALUE)
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return -1; // The sum will overflow an int type
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}
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return (int)result;
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}
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/*---- Constants ----*/
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static final int[] ALPHANUMERIC_MAP;
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static {
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final String ALPHANUMERIC_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
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int maxCh = -1;
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for (int i = 0; i < ALPHANUMERIC_CHARSET.length(); i++)
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maxCh = Math.max(ALPHANUMERIC_CHARSET.charAt(i), maxCh);
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ALPHANUMERIC_MAP = new int[maxCh + 1];
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Arrays.fill(ALPHANUMERIC_MAP, -1);
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for (int i = 0; i < ALPHANUMERIC_CHARSET.length(); i++)
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ALPHANUMERIC_MAP[ALPHANUMERIC_CHARSET.charAt(i)] = i;
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}
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/*---- Public helper enumeration ----*/
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/**
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* Describes how a segment's data bits are interpreted.
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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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ECI (0x7, 0, 0, 0);
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/*-- Fields --*/
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// The mode indicator bits, which is a uint4 value (range 0 to 15).
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final int modeBits;
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// Number of character count bits for three different version ranges.
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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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modeBits = mode;
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numBitsCharCount = ccbits;
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}
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/*-- Method --*/
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// Returns the bit width of the character count field for a segment in this mode
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// in a QR Code at the given version number. The result is in the range [0, 16].
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int numCharCountBits(int ver) {
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assert QrCode.MIN_VERSION <= ver && ver <= QrCode.MAX_VERSION;
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return numBitsCharCount[(ver + 7) / 17];
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}
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}
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}
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