diff options
Diffstat (limited to 'lpg/libqr/code-create.c')
| -rw-r--r-- | lpg/libqr/code-create.c | 206 |
1 files changed, 199 insertions, 7 deletions
diff --git a/lpg/libqr/code-create.c b/lpg/libqr/code-create.c index ef419d3..5582a30 100644 --- a/lpg/libqr/code-create.c +++ b/lpg/libqr/code-create.c @@ -11,6 +11,15 @@ #define MIN(a, b) ((b) < (a) ? (b) : (a)) +static int mask_data(struct qr_code * code); +static int score_mask(const struct qr_bitmap * bmp); +static int score_runs(const struct qr_bitmap * bmp, int base); +static int count_2blocks(const struct qr_bitmap * bmp); +static int count_locators(const struct qr_bitmap * bmp); +static int calc_bw_balance(const struct qr_bitmap * bmp); +static int get_px(const struct qr_bitmap * bmp, int x, int y); +static int get_mask(const struct qr_bitmap * bmp, int x, int y); + /* FIXME: the static functions should be in a better * order, with prototypes. */ @@ -32,13 +41,6 @@ static void x_dump(struct qr_bitstream * bits) printf("\n"); } -static int mask_data(struct qr_code * code) -{ - /* XXX */ - code->modules = qr_mask_apply(code->modules, 2); - return 2; -} - static void setpx(struct qr_bitmap * bmp, int x, int y) { size_t off = y * bmp->stride + x / CHAR_BIT; @@ -274,3 +276,193 @@ fail: goto exit; } +static int mask_data(struct qr_code * code) +{ + struct qr_bitmap * mask, * test; + int selected, score; + int i, best; + + mask = 0; + + /* Generate bitmap for each mask and evaluate */ + for (i = 0; i < 8; ++i) { + test = qr_mask_apply(code->modules, i); + if (!test) { + qr_bitmap_destroy(mask); + return -1; + } + score = score_mask(test); + printf("mask %d scored %d\n", i, score); + if (!mask || score < best) { + best = score; + selected = i; + qr_bitmap_destroy(mask); + mask = test; + } else { + qr_bitmap_destroy(test); + } + } + printf("Selected mask %d (%d)\n", selected, best); + + qr_bitmap_destroy(code->modules); + code->modules = mask; + + return selected; +} + +static int score_mask(const struct qr_bitmap * bmp) +{ + const int N[4] = { 3, 3, 40, 10 }; + int score = 0; + + score += score_runs(bmp, N[0]); + score += N[1] * count_2blocks(bmp); + score += N[2] * count_locators(bmp); + score += N[3] * ((abs(calc_bw_balance(bmp) - 50) + 4) / 5); + + return score; +} + +static int score_runs(const struct qr_bitmap * bmp, int base) +{ + /* Runs of 5+n bits -> N[0] + i */ + int x, y, flip; + int score = 0; + int count, last; + + for (flip = 0; flip <= 1; ++flip) { + for (y = 0; y < bmp->height; ++y) { + count = 0; + for (x = 0; x < bmp->width; ++x) { + int mask, bit; + if (flip) { + mask = get_mask(bmp, y, x); + bit = get_mask(bmp, y, x); + } else { + mask = get_mask(bmp, x, y); + bit = get_px(bmp, x, y); + } + + if (mask && + (count == 0 || !!bit == !!last)) { + ++count; + last = bit; + } else { + if (count >= 5) + score += base + count - 5; + count = 0; + } + } + } + } + + return score; +} + +static int count_2blocks(const struct qr_bitmap * bmp) +{ + /* Count the number of 2x2 blocks (on or off) */ + int x, y; + int count = 0; + + /* Slow and stupid */ + for (y = 0; y < bmp->height - 1; ++y) { + for (x = 0; x < bmp->width - 1; ++x) { + if (get_mask(bmp, x, y) && + get_mask(bmp, x+1, y) && + get_mask(bmp, x, y+1) && + get_mask(bmp, x+1, y+1)) { + int v[4]; + v[0] = get_px(bmp, x, y); + v[1] = get_px(bmp, x+1, y); + v[2] = get_px(bmp, x, y+1); + v[3] = get_px(bmp, x+1, y+1); + if (!(v[0] || v[1] || v[2] || v[3]) || + (v[0] && v[1] && v[2] && v[3])) { + ++count; + } + } + } + } + + return count; +} + +static int count_locators(const struct qr_bitmap * bmp) +{ + /* 1:1:3:1:1 patterns -> N[2] */ + int x, y, flip; + int count = 0; + + for (flip = 0; flip <= 1; ++flip) { + for (y = 0; y < bmp->height - 7; ++y) { + for (x = 0; x < bmp->width - 7; ++x) { + int bits[7]; + int i; + + for (i = 0; i < 7; ++i) + if (!(flip ? get_mask(bmp, y, x+i) : get_mask(bmp, x+i, y))) + continue; + + for (i = 0; i < 7; ++i) + bits[i] = flip ? get_px(bmp, y, x+i) : get_px(bmp, x+i, y); + + if (!bits[0]) + for (i = 0; i < 7; ++i) + bits[i] = !bits[i]; + + if ( bits[0] && !bits[1] && bits[2] && + bits[3] && bits[4] && !bits[5] && + bits[6]) + ++count; + } + } + } + + return count; +} + +static int calc_bw_balance(const struct qr_bitmap * bmp) +{ + /* Calculate the proportion (in percent) of "on" bits */ + int x, y; + unsigned char bit; + long on, total; + + assert(bmp->mask); /* we only need this case */ + + on = total = 0; + for (y = 0; y < bmp->height; ++y) { + size_t off = y * bmp->stride; + unsigned char * bits = bmp->bits + off; + unsigned char * mask = bmp->mask + off; + + for (x = 0; x < bmp->width / CHAR_BIT; ++x, ++bits, ++mask) { + for (bit = 1; bit; bit <<= 1) { + int m = *mask & bit; + + total += !!m; + on += !!(*bits & m); + } + } + } + + return (on * 100) / total; +} + +static int get_px(const struct qr_bitmap * bmp, int x, int y) +{ + size_t off = y * bmp->stride + x / CHAR_BIT; + unsigned char bit = 1 << (x % CHAR_BIT); + + return bmp->bits[off] & bit; +} + +static int get_mask(const struct qr_bitmap * bmp, int x, int y) +{ + size_t off = y * bmp->stride + x / CHAR_BIT; + unsigned char bit = 1 << (x % CHAR_BIT); + + return bmp->mask[off] & bit; +} + |