@ -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 fa il s to fit in the largest version QR Code , which means it is too long
* @throws IllegalArgumentException if the data 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
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" ) ;
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 )
break ; // This version number is found to be suitable
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).
Nayuki Minase
9 years ago