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Merge pull request #89 from claudiofelber/master

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Support horizontally flipped QR-codes according to ISO 18004:2015
This commit is contained in:
Alexandre Perrin 2020-09-23 22:09:39 +02:00 committed by GitHub
commit 7e7ab596e4
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GPG key ID: 4AEE18F83AFDEB23
7 changed files with 55 additions and 6 deletions
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1
.gitignore vendored
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@ -9,3 +9,4 @@ libquirc.so*
.*.swp
*~
.DS_Store
.idea

17
README.md
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@ -174,6 +174,23 @@ for (i = 0; i < num_codes; i++) {
`quirc_code` and `quirc_data` are flat structures which don't need to be
initialized or freed after use.
In case you also need to support horizontally flipped QR-codes (mirrored
images according to ISO 18004:2015, pages 6 and 62), you can make a second
decode attempt with the flipped image data whenever you get an ECC failure:
```C
err = quirc_decode(&code, &data);
if (err == QUIRC_ERROR_DATA_ECC) {
quirc_flip(&code);
err = quirc_decode(&code, &data);
}
if (err)
printf("DECODE FAILED: %s\n", quirc_strerror(err));
else
printf("Data: %s\n", data.payload);
```
Copyright
---------
Copyright (C) 2010-2012 Daniel Beer <<dlbeer@gmail.com>>

15
lib/decode.c
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@ -916,3 +916,18 @@ quirc_decode_error_t quirc_decode(const struct quirc_code *code,
return QUIRC_SUCCESS;
}
void quirc_flip(struct quirc_code *code)
{
struct quirc_code flipped = {0};
unsigned int offset = 0;
for (int y = 0; y < code->size; y++) {
for (int x = 0; x < code->size; x++) {
if (grid_bit(code, y, x)) {
flipped.cell_bitmap[offset >> 3u] |= (1u << (offset & 7u));
}
offset++;
}
}
memcpy(&code->cell_bitmap, &flipped.cell_bitmap, sizeof(flipped.cell_bitmap));
}

3
lib/quirc.h
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@ -168,6 +168,9 @@ void quirc_extract(const struct quirc *q, int index,
quirc_decode_error_t quirc_decode(const struct quirc_code *code,
struct quirc_data *data);
/* Flip a QR-code according to optional mirror feature of ISO 18004:2015 */
void quirc_flip(struct quirc_code *code);
#ifdef __cplusplus
}
#endif

4
tests/inspect.c
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@ -34,6 +34,10 @@ static void dump_info(struct quirc *q)
quirc_extract(q, i, &code);
err = quirc_decode(&code, &data);
if (err == QUIRC_ERROR_DATA_ECC) {
quirc_flip(&code);
err = quirc_decode(&code, &data);
}
dump_cells(&code);
printf("\n");

19
tests/qrtest.c
View file

@ -125,9 +125,16 @@ static int scan_file(const char *path, const char *filename,
quirc_extract(decoder, i, &code);
if (!quirc_decode(&code, &data))
quirc_decode_error_t err = quirc_decode(&code, &data);
if (err == QUIRC_ERROR_DATA_ECC) {
quirc_flip(&code);
err = quirc_decode(&code, &data);
}
if (!err) {
info->decode_count++;
}
}
(void)clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &tp);
info->total_time += MS(tp) - total_start;
@ -150,12 +157,14 @@ static int scan_file(const char *path, const char *filename,
if (want_verbose) {
struct quirc_data data;
quirc_decode_error_t err =
quirc_decode(&code, &data);
quirc_decode_error_t err = quirc_decode(&code, &data);
if (err == QUIRC_ERROR_DATA_ECC) {
quirc_flip(&code);
err = quirc_decode(&code, &data);
}
if (err) {
printf(" ERROR: %s\n\n",
quirc_strerror(err));
printf(" ERROR: %s\n\n", quirc_strerror(err));
} else {
printf(" Decode successful:\n");
dump_data(&data);