diff --git a/lib/identify.c b/lib/identify.c index 44fa48d..098e36f 100644 --- a/lib/identify.c +++ b/lib/identify.c @@ -648,131 +648,31 @@ static void find_leftmost_to_line(void *user_data, int y, int left, int right) } } -/* Do a Bresenham scan from one point to another and count the number - * of black/white transitions. - */ -static int timing_scan(const struct quirc *q, - const struct quirc_point *p0, - const struct quirc_point *p1) +static double distance(struct quirc_point a, struct quirc_point b) { - int n = p1->x - p0->x; - int d = p1->y - p0->y; - int x = p0->x; - int y = p0->y; - int *dom, *nondom; - int dom_step; - int nondom_step; - int a = 0; - int i; - int run_length = 0; - int count = 0; - - if (p0->x < 0 || p0->y < 0 || p0->x >= q->w || p0->y >= q->h) - return -1; - if (p1->x < 0 || p1->y < 0 || p1->x >= q->w || p1->y >= q->h) - return -1; - - if (abs(n) > abs(d)) { - int swap = n; - - n = d; - d = swap; - - dom = &x; - nondom = &y; - } else { - dom = &y; - nondom = &x; - } - - if (n < 0) { - n = -n; - nondom_step = -1; - } else { - nondom_step = 1; - } - - if (d < 0) { - d = -d; - dom_step = -1; - } else { - dom_step = 1; - } - - x = p0->x; - y = p0->y; - for (i = 0; i <= d; i++) { - int pixel; - - if (y < 0 || y >= q->h || x < 0 || x >= q->w) - break; - - pixel = q->pixels[y * q->w + x]; - - if (pixel) { - if (run_length >= 2) - count++; - run_length = 0; - } else { - run_length++; - } - - a += n; - *dom += dom_step; - if (a >= d) { - *nondom += nondom_step; - a -= d; - } - } - - return count; + return sqrt((a.x - b.x)*(a.x - b.x) + (a.y - b.y)*(a.y - b.y)); } - -/* Try the measure the timing pattern for a given QR code. This does - * not require the global perspective to have been set up, but it - * does require that the capstone corners have been set to their - * canonical rotation. - * - * For each capstone, we find a point in the middle of the ring band - * which is nearest the centre of the code. Using these points, we do - * a horizontal and a vertical timing scan. +/* Estimate grid size by determing distance between capstones */ -static int measure_timing_pattern(struct quirc *q, int index) +static void measure_grid_size(struct quirc *q, int index) { struct quirc_grid *qr = &q->grids[index]; - int i; - int scan; - int ver; - int size; - for (i = 0; i < 3; i++) { - static const double us[] = {6.5, 6.5, 0.5}; - static const double vs[] = {0.5, 6.5, 6.5}; - struct quirc_capstone *cap = &q->capstones[qr->caps[i]]; + struct quirc_capstone *a = &(q->capstones[qr->caps[0]]); + struct quirc_capstone *b = &(q->capstones[qr->caps[1]]); + struct quirc_capstone *c = &(q->capstones[qr->caps[2]]); - perspective_map(cap->c, us[i], vs[i], &qr->tpep[i]); - } + double ab = distance(b->corners[0], a->corners[3]); + double capstone_ab_size = (distance(b->corners[0], b->corners[3]) + distance(a->corners[0], a->corners[3]))/2.0; + double ver_grid = 7.0 * ab / capstone_ab_size; - qr->hscan = timing_scan(q, &qr->tpep[1], &qr->tpep[2]); - qr->vscan = timing_scan(q, &qr->tpep[1], &qr->tpep[0]); - - scan = qr->hscan; - if (qr->vscan > scan) - scan = qr->vscan; - - /* If neither scan worked, we can't go any further. */ - if (scan < 0) - return -1; - - /* Choose the nearest allowable grid size */ - size = scan * 2 + 13; - ver = (size - 15) / 4; - if (ver > QUIRC_MAX_VERSION) { - return -1; - } - - qr->grid_size = ver * 4 + 17; - return 0; + double bc = distance(b->corners[0], c->corners[1]); + double capstone_bc_size = (distance(b->corners[0], b->corners[1]) + distance(c->corners[0], c->corners[1]))/2.0; + double hor_grid = 7.0 * bc / capstone_bc_size; + + double grid_size_estimate = (ver_grid + hor_grid) / 2; + + qr->grid_size = 4*((int)(grid_size_estimate - 17.0 + 2.0) / 4) + 17; } /* Read a cell from a grid using the currently set perspective @@ -1036,12 +936,10 @@ static void record_qr_grid(struct quirc *q, int a, int b, int c) cap->qr_grid = qr_index; } - /* Check the timing pattern. This doesn't require a perspective + /* Check the timing pattern by measuring grid size. This doesn't require a perspective * transform. */ - if (measure_timing_pattern(q, qr_index) < 0) - goto fail; - + measure_grid_size(q, qr_index); /* Make an estimate based for the alignment pattern based on extending * lines from capstones A and C. */ @@ -1108,31 +1006,16 @@ static void test_neighbours(struct quirc *q, int i, const struct neighbour_list *hlist, const struct neighbour_list *vlist) { - int j, k; - double best_score = 0.0; - int best_h = -1, best_v = -1; - /* Test each possible grouping */ - for (j = 0; j < hlist->count; j++) - for (k = 0; k < vlist->count; k++) { - const struct neighbour *hn = &hlist->n[j]; + for (int j = 0; j < hlist->count; j++) { + const struct neighbour *hn = &hlist->n[j]; + for (int k = 0; k < vlist->count; k++) { const struct neighbour *vn = &vlist->n[k]; - double score = fabs(1.0 - hn->distance / vn->distance); - - if (score > 2.5) - continue; - - if (best_h < 0 || score < best_score) { - best_h = hn->index; - best_v = vn->index; - best_score = score; - } + double squareness = fabs(1.0 - hn->distance / vn->distance); + if (squareness < 0.2) + record_qr_grid(q, hn->index, i, vn->index); } - - if (best_h < 0 || best_v < 0) - return; - - record_qr_grid(q, best_h, i, best_v); + } } static void test_grouping(struct quirc *q, unsigned int i) @@ -1142,9 +1025,6 @@ static void test_grouping(struct quirc *q, unsigned int i) struct neighbour_list hlist; struct neighbour_list vlist; - if (c1->qr_grid >= 0) - return; - hlist.count = 0; vlist.count = 0; @@ -1155,7 +1035,7 @@ static void test_grouping(struct quirc *q, unsigned int i) struct quirc_capstone *c2 = &q->capstones[j]; double u, v; - if (i == j || c2->qr_grid >= 0) + if (i == j) continue; perspective_unmap(c1->c, &c2->center, &u, &v); diff --git a/lib/quirc_internal.h b/lib/quirc_internal.h index 0d8a229..37b4e4d 100644 --- a/lib/quirc_internal.h +++ b/lib/quirc_internal.h @@ -32,7 +32,8 @@ #define QUIRC_MAX_REGIONS 254 #endif #define QUIRC_MAX_CAPSTONES 32 -#define QUIRC_MAX_GRIDS 8 +#define QUIRC_MAX_GRIDS (QUIRC_MAX_CAPSTONES * 2) + #define QUIRC_PERSPECTIVE_PARAMS 8 #if QUIRC_MAX_REGIONS < UINT8_MAX @@ -72,8 +73,6 @@ struct quirc_grid { /* Timing pattern endpoints */ struct quirc_point tpep[3]; - int hscan; - int vscan; /* Grid size and perspective transform */ int grid_size;