From 59e3933e8ba7d54c96652c9517b7291d39a46afd Mon Sep 17 00:00:00 2001 From: Project Nayuki Date: Wed, 3 Oct 2018 21:14:45 +0000 Subject: [PATCH] Added and updated comments in Java QrSegmentAdvanced. --- .../nayuki/qrcodegen/QrSegmentAdvanced.java | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java b/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java index 8369a6c..dfad00b 100644 --- a/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java +++ b/java/io/nayuki/qrcodegen/QrSegmentAdvanced.java @@ -37,9 +37,9 @@ public final class QrSegmentAdvanced { /*---- Optimal list of segments encoder ----*/ /** - * Returns a new mutable list of zero or more segments to represent the specified Unicode text string. - * The resulting list optimally minimizes the total encoded bit length, subjected to the constraints given - * by the specified {error correction level, minimum version number, maximum version number}. + * Returns a list of zero or more segments to represent the specified Unicode text string. + * The resulting list optimally minimizes the total encoded bit length, subjected to the constraints + * in the specified {error correction level, minimum version number, maximum version number}. *

This function can utilize all four text encoding modes: numeric, alphanumeric, byte, and kanji. * This can be viewed as a significantly more sophisticated and slower replacement for * {@link QrSegment#makeSegments(String)}, but requiring more input parameters in a way @@ -48,7 +48,7 @@ public final class QrSegmentAdvanced { * @param ecl the error correction level to use * @param minVersion the minimum allowed version of the QR symbol (at least 1) * @param maxVersion the maximum allowed version of the QR symbol (at most 40) - * @return a list of segments containing the text, minimizing the bit length with respect to the constraints + * @return a new mutable list of segments containing the text, minimizing the bit length with respect to the constraints * @throws NullPointerException if the data or error correction level is {@code null} * @throws IllegalArgumentException if 1 ≤ minVersion ≤ maxVersion ≤ 40 is violated, * or if the data is too long to fit in a QR Code at maxVersion at the ECL @@ -87,6 +87,7 @@ public final class QrSegmentAdvanced { } + // Returns an array representing the optimal mode per code point based on the given text and version. private static Mode[] computeCharacterModes(int[] codePoints, int version) { if (codePoints.length == 0) throw new IllegalArgumentException(); @@ -112,16 +113,16 @@ public final class QrSegmentAdvanced { for (int i = 0; i < codePoints.length; i++) { int c = codePoints[i]; int[] curCosts = new int[numModes]; - { // Always extend a bytes segment + { // Always extend a byte mode segment curCosts[0] = prevCosts[0] + countUtf8Bytes(c) * 8 * 6; charModes[i][0] = modeTypes[0]; } // Extend a segment if possible - if (QrSegment.ALPHANUMERIC_CHARSET.indexOf(c) != -1) { + if (QrSegment.ALPHANUMERIC_CHARSET.indexOf(c) != -1) { // Is alphanumeric curCosts[1] = prevCosts[1] + 33; // 5.5 bits per alphanumeric char charModes[i][1] = modeTypes[1]; } - if ('0' <= c && c <= '9') { + if ('0' <= c && c <= '9') { // Is numeric curCosts[2] = prevCosts[2] + 20; // 3.33 bits per digit charModes[i][2] = modeTypes[2]; } @@ -168,6 +169,8 @@ public final class QrSegmentAdvanced { } + // Returns a list of segments based on the given text and modes, such that + // consecutive code points in the same mode are put into the same segment. private static List splitIntoSegments(int[] codePoints, Mode[] charModes) { if (codePoints.length == 0) throw new IllegalArgumentException(); @@ -198,6 +201,7 @@ public final class QrSegmentAdvanced { } + // Returns an array of Unicode code points (effectively UTF-32 / UCS-4) representing the given UTF-16 string. private static int[] toCodePoints(String s) { int[] result = s.codePoints().toArray(); for (int c : result) { @@ -208,6 +212,7 @@ public final class QrSegmentAdvanced { } + // Returns the number of UTF-8 bytes needed to encode the given Unicode code point. private static int countUtf8Bytes(int cp) { if (cp < 0) throw new IllegalArgumentException("Invalid code point"); else if (cp < 0x80) return 1;