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refactor(fast_corners): de-duplicate fast_corners module (#47) #64

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Merged
kalwalt merged 1 commit into from
Jul 8, 2026
Merged

refactor(fast_corners): de-duplicate fast_corners module (#47) #64

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231 changes: 228 additions & 3 deletions src/fast_corners/fast_corners.ts
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Original file line number Diff line number Diff line change
@@ -1,10 +1,235 @@
import jsfeatNext from "../core/core";
import { matrix_t } from "../matrix_t/matrix_t";
import { point_t } from "../point_t/point_t";
export class fast_corners {
import { _cmp_score_16 } from "./fast_private";

/**
* Real implementation, moved out of the src/jsfeatNext.ts monolith (issue #47).
* This file previously held a type-only stub whose methods threw
* "Method not implemented." — the implementation below is the inline code
* from the monolith, verbatim.
*/
export class fast_corners extends jsfeatNext {
private offsets16: Int32Array;
public _threshold: number;
public threshold_tab: Uint8Array;
public pixel_off: Int32Array;
public score_diff: Int32Array;

constructor() {
super();
this.offsets16 = new Int32Array([
0, 3, 1, 3, 2, 2, 3, 1, 3, 0, 3, -1, 2, -2, 1, -3, 0, -3, -1, -3, -2, -2, -3, -1, -3, 0, -3, 1, -2, 2, -1,
3,
]);
this.threshold_tab = new Uint8Array(512);
this._threshold = 20;
this.pixel_off = new Int32Array(25);
this.score_diff = new Int32Array(25);
}

set_threshold(threshold: number): number {
throw new Error("Method not implemented.");
this._threshold = Math.min(Math.max(threshold, 0), 255);
for (let i = -255; i <= 255; ++i) {
this.threshold_tab[i + 255] = i < -this._threshold ? 1 : i > this._threshold ? 2 : 0;
}
return this._threshold;
}

detect(src: matrix_t, corners: point_t[], border: number): number {
throw new Error("Method not implemented.");
if (typeof border === "undefined") {
border = 3;
}

const K = 8,
N = 25;
const img = src.data,
w = src.cols,
h = src.rows;
let i = 0,
j = 0,
k = 0,
vt = 0,
x = 0,
m3 = 0;
const buf_node = this.cache.get_buffer(3 * w);
const cpbuf_node = this.cache.get_buffer(((w + 1) * 3) << 2);
const buf = buf_node.u8;
const cpbuf = cpbuf_node.i32;
const pixel = this.pixel_off;
const sd = this.score_diff;
const sy = Math.max(3, border);
const ey = Math.min(h - 2, h - border);
const sx = Math.max(3, border);
const ex = Math.min(w - 3, w - border);
let _count = 0,
corners_cnt = 0,
pt;
const score_func = _cmp_score_16;
const thresh_tab = this.threshold_tab;
const threshold = this._threshold;

let v = 0,
tab = 0,
d = 0,
ncorners = 0,
cornerpos = 0,
curr = 0,
ptr = 0,
prev = 0,
pprev = 0;
let jp1 = 0,
jm1 = 0,
score = 0;

this._cmp_offsets(pixel, w, 16);

// local vars are faster?
const pixel0 = pixel[0];
const pixel1 = pixel[1];
const pixel2 = pixel[2];
const pixel3 = pixel[3];
const pixel4 = pixel[4];
const pixel5 = pixel[5];
const pixel6 = pixel[6];
const pixel7 = pixel[7];
const pixel8 = pixel[8];
const pixel9 = pixel[9];
const pixel10 = pixel[10];
const pixel11 = pixel[11];
const pixel12 = pixel[12];
const pixel13 = pixel[13];
const pixel14 = pixel[14];
const pixel15 = pixel[15];

for (i = 0; i < w * 3; ++i) {
buf[i] = 0;
}

for (i = sy; i < ey; ++i) {
ptr = (i * w + sx) | 0;
m3 = (i - 3) % 3;
curr = (m3 * w) | 0;
cornerpos = (m3 * (w + 1)) | 0;
for (j = 0; j < w; ++j) buf[curr + j] = 0;
ncorners = 0;

if (i < ey - 1) {
j = sx;

for (; j < ex; ++j, ++ptr) {
v = img[ptr];
tab = -v + 255;
d = thresh_tab[tab + img[ptr + pixel0]] | thresh_tab[tab + img[ptr + pixel8]];

if (d == 0) {
continue;
}

d &= thresh_tab[tab + img[ptr + pixel2]] | thresh_tab[tab + img[ptr + pixel10]];
d &= thresh_tab[tab + img[ptr + pixel4]] | thresh_tab[tab + img[ptr + pixel12]];
d &= thresh_tab[tab + img[ptr + pixel6]] | thresh_tab[tab + img[ptr + pixel14]];

if (d == 0) {
continue;
}

d &= thresh_tab[tab + img[ptr + pixel1]] | thresh_tab[tab + img[ptr + pixel9]];
d &= thresh_tab[tab + img[ptr + pixel3]] | thresh_tab[tab + img[ptr + pixel11]];
d &= thresh_tab[tab + img[ptr + pixel5]] | thresh_tab[tab + img[ptr + pixel13]];
d &= thresh_tab[tab + img[ptr + pixel7]] | thresh_tab[tab + img[ptr + pixel15]];

if (d & 1) {
vt = v - threshold;
_count = 0;

for (k = 0; k < N; ++k) {
x = img[ptr + pixel[k]];
if (x < vt) {
++_count;
if (_count > K) {
++ncorners;
cpbuf[cornerpos + ncorners] = j;
buf[curr + j] = score_func(img, ptr, pixel, sd, threshold);
break;
}
} else {
_count = 0;
}
}
}

if (d & 2) {
vt = v + threshold;
_count = 0;

for (k = 0; k < N; ++k) {
x = img[ptr + pixel[k]];
if (x > vt) {
++_count;
if (_count > K) {
++ncorners;
cpbuf[cornerpos + ncorners] = j;
buf[curr + j] = score_func(img, ptr, pixel, sd, threshold);
break;
}
} else {
_count = 0;
}
}
}
}
}

cpbuf[cornerpos + w] = ncorners;

if (i == sy) {
continue;
}

m3 = (i - 4 + 3) % 3;
prev = (m3 * w) | 0;
cornerpos = (m3 * (w + 1)) | 0;
m3 = (i - 5 + 3) % 3;
pprev = (m3 * w) | 0;

ncorners = cpbuf[cornerpos + w];

for (k = 0; k < ncorners; ++k) {
j = cpbuf[cornerpos + k];
jp1 = (j + 1) | 0;
jm1 = (j - 1) | 0;
score = buf[prev + j];
if (
score > buf[prev + jp1] &&
score > buf[prev + jm1] &&
score > buf[pprev + jm1] &&
score > buf[pprev + j] &&
score > buf[pprev + jp1] &&
score > buf[curr + jm1] &&
score > buf[curr + j] &&
score > buf[curr + jp1]
) {
// save corner
pt = corners[corners_cnt];
(pt.x = j), (pt.y = i - 1), (pt.score = score);
corners_cnt++;
}
}
} // y loop
this.cache.put_buffer(buf_node);
this.cache.put_buffer(cpbuf_node);
return corners_cnt;
}

private _cmp_offsets(pixel: Uint8Array | Int32Array, step: number, pattern_size: number): void {
let k = 0;
const offsets = this.offsets16;
for (; k < pattern_size; ++k) {
pixel[k] = offsets[k << 1] + offsets[(k << 1) + 1] * step;
}
for (; k < 25; ++k) {
pixel[k] = pixel[k - pattern_size];
}
}
}
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