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https://github.com/zint/zint
synced 2024-11-16 20:57:25 +13:00
Improved data compression algorithm for QR Code
This commit is contained in:
Robin Stuart
parent
001a0a88d9
commit
653105b81d
345
backend/qr.c
345
backend/qr.c
@ -761,7 +761,7 @@ int write_log(char log[])
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}
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#endif
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int evaluate(unsigned char *grid, int size, int pattern)
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int evaluate(unsigned char *eval, int size, int pattern)
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{
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int x, y, block, weight;
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int result = 0;
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@ -791,16 +791,11 @@ int evaluate(unsigned char *grid, int size, int pattern)
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// all eight bitmask variants have been encoded in the 8 bits of the bytes that make up the grid array. select them for evaluation according to the desired pattern.
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for(x = 0; x < size; x++) {
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for(y = 0; y < size; y++) {
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switch(pattern) {
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case 0: if (grid[(y * size) + x] & 0x01) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 1: if (grid[(y * size) + x] & 0x02) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 2: if (grid[(y * size) + x] & 0x04) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 3: if (grid[(y * size) + x] & 0x08) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 4: if (grid[(y * size) + x] & 0x10) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 5: if (grid[(y * size) + x] & 0x20) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 6: if (grid[(y * size) + x] & 0x40) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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case 7: if (grid[(y * size) + x] & 0x80) { local[(y * size) + x] = '1'; } else { local[(y * size) + x] = '0'; } break;
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}
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if ((eval[(y * size) + x] & (0x01 << pattern)) != 0) {
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local[(y * size) + x] = '1';
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} else {
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local[(y * size) + x] = '0';
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}
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}
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}
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@ -819,7 +814,7 @@ int evaluate(unsigned char *grid, int size, int pattern)
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/* Test 1: Adjacent modules in row/column in same colour */
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/* Vertical */
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for(x = 0; x < size; x++) {
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/*for(x = 0; x < size; x++) {
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state = local[x];
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block = 0;
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for(y = 0; y < size; y++) {
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@ -834,10 +829,10 @@ int evaluate(unsigned char *grid, int size, int pattern)
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block=0;
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}
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}
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}
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}*/
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/* Horizontal */
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for(y = 0; y < size; y++) {
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/*for(y = 0; y < size; y++) {
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state = local[y * size];
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block = 0;
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for(x = 0; x < size; x++) {
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@ -852,8 +847,49 @@ int evaluate(unsigned char *grid, int size, int pattern)
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block=0;
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}
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}
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}
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}*/
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/* Test 1: Adjacent modules in row/column in same colour */
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/* Vertical */
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for (x = 0; x < size; x++) {
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state = local[x];
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block = 0;
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for (y = 0; y < size; y++) {
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if (local[(y * size) + x] == state) {
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block++;
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} else {
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if (block > 5) {
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result += (3 + (block - 5));
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}
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block = 0;
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state = local[(y * size) + x];
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}
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}
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if (block > 5) {
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result += (3 + (block - 5));
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}
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}
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/* Horizontal */
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for (y = 0; y < size; y++) {
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state = local[y * size];
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block = 0;
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for (x = 0; x < size; x++) {
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if (local[(y * size) + x] == state) {
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block++;
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} else {
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if (block > 5) {
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result += (3 + (block - 5));
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}
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block = 0;
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state = local[(y * size) + x];
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}
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}
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if (block > 5) {
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result += (3 + (block - 5));
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}
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}
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#ifdef ZINTLOG
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/* output Test 1 */
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sprintf(str, "%d", result);
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@ -871,7 +907,7 @@ int evaluate(unsigned char *grid, int size, int pattern)
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}
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}
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}
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#ifdef ZINTLOG
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/* output Test 2 */
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sprintf(str, "%d", result-result_b);
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@ -1098,7 +1134,7 @@ int apply_bitmask(unsigned char *grid, int size, int ecc_level)
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add_format_info_eval(eval, size, ecc_level, pattern);
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penalty[pattern] = evaluate(eval, size, pattern);
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penalty[pattern] = evaluate(eval, size, pattern);
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}
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best_pattern = 0;
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@ -1197,11 +1233,216 @@ void add_version_info(unsigned char *grid, int size, int version)
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}
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}
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int tribus(int version, int a, int b, int c) {
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/* Choose from three numbers based on version */
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int RetVal;
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RetVal = c;
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if (version < 10) {
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RetVal = a;
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}
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if ((version >= 10) && (version <= 26)) {
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RetVal = b;
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}
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return RetVal;
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}
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void applyOptimisation(int version, char inputMode[], int inputLength) {
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/* Implements a custom optimisation algorithm, more efficient than that
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given in Annex J.
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*/
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int blockCount = 0;
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int i, j;
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char currentMode = ' '; // Null
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for (i = 0; i < inputLength; i++) {
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if (inputMode[i] != currentMode) {
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currentMode = inputMode[i];
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blockCount++;
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}
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}
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int blockLength[blockCount];
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char blockMode[blockCount];
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j = -1;
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currentMode = ' '; // Null
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for (i = 0; i < inputLength; i++) {
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if (inputMode[i] != currentMode) {
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j++;
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blockLength[j] = 1;
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blockMode[j] = inputMode[i];
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currentMode = inputMode[i];
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} else {
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blockLength[j]++;
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}
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}
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if (blockCount > 1) {
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// Search forward
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for (i = 0; i <= (blockCount - 2); i++) {
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if (blockMode[i] == 'B') {
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switch (blockMode[i + 1]) {
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case 'K':
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if (blockLength[i + 1] < tribus(version, 4, 5, 6)) {
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blockMode[i + 1] = 'B';
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}
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break;
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case 'A':
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if (blockLength[i + 1] < tribus(version, 7, 8, 9)) {
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blockMode[i + 1] = 'B';
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}
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break;
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case 'N':
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if (blockLength[i + 1] < tribus(version, 3, 4, 5)) {
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blockMode[i + 1] = 'B';
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}
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break;
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}
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}
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if ((blockMode[i] == 'A')
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&& (blockMode[i + 1] == 'N')) {
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if (blockLength[i + 1] < tribus(version, 6, 8, 10)) {
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blockMode[i + 1] = 'A';
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}
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}
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}
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// Search backward
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for (i = blockCount - 1; i > 0; i--) {
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if (blockMode[i] == 'B') {
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switch (blockMode[i - 1]) {
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case 'K':
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if (blockLength[i - 1] < tribus(version, 4, 5, 6)) {
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blockMode[i - 1] = 'B';
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}
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break;
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case 'A':
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if (blockLength[i - 1] < tribus(version, 7, 8, 9)) {
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blockMode[i - 1] = 'B';
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}
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break;
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case 'N':
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if (blockLength[i - 1] < tribus(version, 3, 4, 5)) {
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blockMode[i - 1] = 'B';
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}
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break;
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}
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}
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if ((blockMode[i] == 'A')
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&& (blockMode[i - 1] == 'N')) {
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if (blockLength[i - 1] < tribus(version, 6, 8, 10)) {
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blockMode[i - 1] = 'A';
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}
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}
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}
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}
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j = 0;
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for (int block = 0; block < blockCount; block++) {
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currentMode = blockMode[block];
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for (i = 0; i < blockLength[block]; i++) {
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inputMode[j] = currentMode;
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j++;
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}
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}
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}
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int blockLength(int start, char inputMode[], int inputLength) {
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/* Find the length of the block starting from 'start' */
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int i, count;
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char mode = inputMode[start];
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count = 0;
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i = start;
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do {
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count++;
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} while (((i + count) < inputLength) && (inputMode[i + count] == mode));
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return count;
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}
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int getBinaryLength(int version, char inputMode[], int inputData[], int inputLength, int gs1) {
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/* Calculate the actual bitlength of the proposed binary string */
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char currentMode;
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int i, j;
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int count = 0;
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applyOptimisation(version, inputMode, inputLength);
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currentMode = ' '; // Null
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if (gs1 == 1) {
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count += 4;
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}
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for (i = 0; i < inputLength; i++) {
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if (inputMode[i] != currentMode) {
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count += 4;
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switch (inputMode[i]) {
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case 'K':
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count += tribus(version, 8, 10, 12);
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count += (blockLength(i, inputMode, inputLength) * 13);
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break;
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case 'B':
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count += tribus(version, 8, 16, 16);
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for (j = i; j < (i + blockLength(i, inputMode, inputLength)); j++) {
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if (inputData[j] > 0xff) {
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count += 16;
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} else {
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count += 8;
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}
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}
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break;
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case 'A':
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count += tribus(version, 9, 11, 13);
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switch (blockLength(i, inputMode, inputLength) % 2) {
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case 0:
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count += (blockLength(i, inputMode, inputLength) / 2) * 11;
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break;
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case 1:
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count += ((blockLength(i, inputMode, inputLength) - 1) / 2) * 11;
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count += 6;
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break;
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}
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break;
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case 'N':
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count += tribus(version, 10, 12, 14);
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switch (blockLength(i, inputMode, inputLength) % 3) {
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case 0:
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count += (blockLength(i, inputMode, inputLength) / 3) * 10;
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break;
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case 1:
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count += ((blockLength(i, inputMode, inputLength) - 1) / 3) * 10;
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count += 4;
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break;
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case 2:
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count += ((blockLength(i, inputMode, inputLength) - 2) / 3) * 10;
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count += 7;
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break;
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}
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break;
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}
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currentMode = inputMode[i];
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}
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}
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return count;
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}
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int qr_code(struct zint_symbol *symbol, unsigned char source[], int length)
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{
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int error_number, i, j, glyph, est_binlen;
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int ecc_level, autosize, version, max_cw, target_binlen, blocks, size;
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int bitmask, gs1;
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int canShrink;
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#ifndef _MSC_VER
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int utfdata[length + 1];
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@ -1295,16 +1536,66 @@ int qr_code(struct zint_symbol *symbol, unsigned char source[], int length)
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break;
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}
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}
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// Now see if the optimised binary will fit in a smaller symbol.
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canShrink = 1;
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if((symbol->option_2 >= 1) && (symbol->option_2 <= 40)) {
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if (symbol->option_2 > autosize) {
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version = symbol->option_2;
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} else {
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version = autosize;
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}
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} else {
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version = autosize;
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}
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do {
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if (autosize == 1) {
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canShrink = 0;
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} else {
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if (tribus(autosize - 1, 1, 2, 3) != tribus(autosize, 1, 2, 3)) {
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// Length of binary needed to encode the data in the smaller symbol is different, recalculate
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est_binlen = getBinaryLength(autosize - 1, mode, jisdata, length, gs1);
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}
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switch (ecc_level) {
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case LEVEL_L:
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if ((8 * qr_data_codewords_L[autosize - 2]) < est_binlen) {
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canShrink = 0;
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}
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break;
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case LEVEL_M:
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if ((8 * qr_data_codewords_M[autosize - 2]) < est_binlen) {
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canShrink = 0;
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}
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break;
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case LEVEL_Q:
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if ((8 * qr_data_codewords_Q[autosize - 2]) < est_binlen) {
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canShrink = 0;
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}
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break;
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case LEVEL_H:
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if ((8 * qr_data_codewords_H[autosize - 2]) < est_binlen) {
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canShrink = 0;
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}
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break;
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}
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if (canShrink == 1) {
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// Optimisation worked - data will fit in a smaller symbol
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autosize--;
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} else {
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// Data did not fit in the smaller symbol, revert to original size
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if (tribus(autosize - 1, 1, 2, 3) != tribus(autosize, 1, 2, 3)) {
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est_binlen = getBinaryLength(autosize, mode, jisdata, length, gs1);
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}
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}
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}
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} while (canShrink == 1);
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version = autosize;
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if ((symbol->option_2 >= 1) && (symbol->option_2 <= 40)) {
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/* If the user has selected a larger symbol than the smallest available,
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then use the size the user has selected, and re-optimise for this
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symbol size.
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*/
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if (symbol->option_2 > version) {
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version = symbol->option_2;
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est_binlen = getBinaryLength(symbol->option_2, mode, jisdata, length, gs1);
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}
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}
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/* Ensure maxium error correction capacity */
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if(est_binlen <= qr_data_codewords_M[version - 1]) { ecc_level = LEVEL_M; }
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