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Revamped QrCode.encodeSegments() to add parameters to make a much richer API, in all language versions; updated JavaScript demo script to handle new semantics.

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Nayuki Minase
2016-04-16 03:53:58 +00:00
parent ca7e7a60a7
commit 5692e951dd
9 changed files with 205 additions and 113 deletions
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java/io/nayuki/qrcodegen/QrCode.java
+47 -29
View File
@@ -76,49 +76,66 @@ public final class QrCode {
/**
* Returns a QR Code symbol representing the specified data segments at the specified error
* correction level. The smallest possible QR Code version is automatically chosen for the output.
* Returns a QR Code symbol representing the specified data segments at the specified error correction
* level or higher. The smallest possible QR Code version is automatically chosen for the output.
* <p>This function allows the user to create a custom sequence of segments that switches
* between modes (such as alphanumeric and binary) to encode text more efficiently. This
* function is considered to be lower level than simply encoding text or binary data.</p>
* @param segs the segments to encode
* @param ecl the error correction level to use
* @param ecl the error correction level to use (will be boosted)
* @return a QR Code representing the segments
* @throws NullPointerException if the list of segments, a segment, or the error correction level is {@code null}
* @throws IllegalArgumentException if the data fails to fit in the largest version QR Code, which means it is too long
* @throws IllegalArgumentException if the data is too long to fit in the largest version QR Code at the ECL
*/
public static QrCode encodeSegments(List<QrSegment> segs, Ecc ecl) {
return encodeSegments(segs, ecl, 1, 40, -1, true);
}
/**
* Returns a QR Code symbol representing the specified data segments with the specified encoding parameters.
* The smallest possible QR Code version within the specified range is automatically chosen for the output.
* <p>This function allows the user to create a custom sequence of segments that switches
* between modes (such as alphanumeric and binary) to encode text more efficiently.
* This function is considered to be lower level than simply encoding text or binary data.</p>
* @param segs the segments to encode
* @param ecl the error correction level to use (may be boosted)
* @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)
* @param mask the mask pattern to use, which is either -1 for automatic choice or from 0 to 7 for fixed choice
* @param boostEcl increases the error correction level if it can be done without increasing the version number
* @return a QR Code representing the segments
* @throws NullPointerException if the list of segments, a segment, or the error correction level is {@code null}
* @throws IllegalArgumentException if 1 &le; minVersion &le; maxVersion &le; 40 is violated, or if mask
* &lt; &minus;1 or mask > 7, or if the data is too long to fit in a QR Code at maxVersion at the ECL
*/
public static QrCode encodeSegments(List<QrSegment> segs, Ecc ecl, int minVersion, int maxVersion, int mask, boolean boostEcl) {
if (segs == null || ecl == null)
throw new NullPointerException();
if (!(1 <= minVersion && minVersion <= maxVersion && maxVersion <= 40) || mask < -1 || mask > 7)
throw new IllegalArgumentException("Invalid value");
// Find the minimal version number to use
int version, dataCapacityBits;
outer:
for (version = 1; ; version++) { // Increment until the data fits in the QR Code
if (version > 40) // All versions could not fit the given data
throw new IllegalArgumentException("Data too long");
dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
// Calculate the total number of bits needed at this version number
// to encode all the segments (i.e. segment metadata and payloads)
int dataUsedBits = 0;
for (QrSegment seg : segs) {
if (seg == null)
throw new NullPointerException();
if (seg.numChars < 0)
throw new AssertionError();
int ccbits = seg.mode.numCharCountBits(version);
if (seg.numChars >= (1 << ccbits)) {
// Segment length value doesn't fit in the length field's bit-width, so fail immediately
continue outer;
}
dataUsedBits += 4 + ccbits + seg.bitLength;
}
if (dataUsedBits <= dataCapacityBits)
int version, dataUsedBits;
for (version = minVersion; ; version++) {
int dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
dataUsedBits = QrSegment.getTotalBits(segs, version);
if (dataUsedBits != -1 && dataUsedBits <= dataCapacityBits)
break; // This version number is found to be suitable
if (version >= maxVersion) // All versions in the range could not fit the given data
throw new IllegalArgumentException("Data too long");
}
if (dataUsedBits == -1)
throw new AssertionError();
// Increase the error correction level while the data still fits in the current version number
for (Ecc newEcl : Ecc.values()) {
if (boostEcl && dataUsedBits <= getNumDataCodewords(version, newEcl) * 8)
ecl = newEcl;
}
// Create the data bit string by concatenating all segments
int dataCapacityBits = getNumDataCodewords(version, ecl) * 8;
BitBuffer bb = new BitBuffer();
for (QrSegment seg : segs) {
bb.appendBits(seg.mode.modeBits, 4);
@@ -137,7 +154,7 @@ public final class QrCode {
throw new AssertionError();
// Create the QR Code symbol
return new QrCode(version, ecl, bb.getBytes(), -1);
return new QrCode(version, ecl, bb.getBytes(), mask);
}
@@ -732,7 +749,8 @@ public final class QrCode {
* Represents the error correction level used in a QR Code symbol.
*/
public enum Ecc {
// Constants declared in ascending order of error protection.
// These enum constants must be declared in ascending order of error protection,
// for the sake of the implicit ordinal() method and values() function.
LOW(1), MEDIUM(0), QUARTILE(3), HIGH(2);
// In the range 0 to 3 (unsigned 2-bit integer).
java/io/nayuki/qrcodegen/QrSegment.java
+21
View File
@@ -186,6 +186,27 @@ public final class QrSegment {
}
// Package-private helper function.
static int getTotalBits(List<QrSegment> segs, int version) {
if (segs == null)
throw new NullPointerException();
if (version < 1 || version > 40)
throw new IllegalArgumentException("Version number out of range");
int result = 0;
for (QrSegment seg : segs) {
if (seg == null)
throw new NullPointerException();
int ccbits = seg.mode.numCharCountBits(version);
// Fail if segment length value doesn't fit in the length field's bit-width
if (seg.numChars >= (1 << ccbits))
return -1;
result += 4 + ccbits + seg.bitLength;
}
return result;
}
/*---- Constants ----*/
/** Can test whether a string is encodable in numeric mode (such as by using {@link #makeNumeric(String)}). */