LithosAnanake/tools/ttftest.c

/*
  StarForth — Steady-State Virtual Machine Runtime

  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  Licensed under the StarForth License, Version 1.0.
*/

/**
 * ttftest.c — Host-side unit test for src/starkernel/hal/ttf.c (FABRIC.md
 * item 4.3.7). No QEMU needed, same pattern as tools/README.md's fbtest.c
 * entry (that file is itself missing from tools/ — stale doc, reported
 * separately, not fixed here).
 *
 * Expected values below were independently computed by a from-scratch
 * Python/struct reference reader (not this codebase's parser), against
 * JetBrainsMono-Regular.ttf.
 *
 * Usage: ./ttftest <path-to-ttf>
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../include/starkernel/ttf.h"

typedef struct {
    uint32_t codepoint;
    uint32_t expect_glyph;
    int16_t expect_contours;
    int16_t expect_xmin, expect_ymin, expect_xmax, expect_ymax;
    uint32_t expect_glyf_offset;
    uint32_t expect_glyf_length;
} expect_t;

static const expect_t EXPECTED[] = {
    /*   cp     glyph   nc  xmin ymin xmax ymax    off      len */
    {0x0041, 1, 2, 50, 0, 550, 730, 35536, 112},   /* 'A' */
    {0x0061, 198, 2, 67, -10, 508, 560, 46968, 244}, /* 'a' */
    {0x0030, 737, 3, 80, -10, 520, 740, 92152, 184}, /* '0' */
    {0x002E, 908, 1, 218, -10, 382, 152, 110044, 72}, /* '.' */
    {0x0021, 913, 2, 225, -5, 375, 730, 110632, 108}, /* '!' */
    {0x0040, 1151, 2, 45, -180, 560, 740, 144400, 224}, /* '@' */
    {0x0020, 821, 0, 0, 0, 0, 0, 99448, 0},         /* space, empty glyph */
};

static int failures = 0;

static void check_eq_i(const char *what, uint32_t cp, long got, long want) {
    if (got != want) {
        printf("  FAIL U+%04X %s: got %ld want %ld\n", cp, what, got, want);
        failures++;
    }
}

/* Outline expectations (4.3.7a), independently computed by a from-scratch
 * Python outline decoder (tools/../../tmp .../ttf_outline_ref.py, not
 * committed, reproducible from FABRIC.md's 4.3.7a completion note) that
 * shares no code with ttf.c. '.' and '0' are simple glyphs; 'A' is simple
 * with two contours; 'a' is a translation-only composite (2 components). */
typedef struct {
    int32_t x, y;
    int on_curve;
} exp_point_t;

typedef struct {
    uint32_t codepoint;
    uint32_t glyph;
    const uint16_t *contour_ends;
    uint32_t contour_count;
    const exp_point_t *points;
    uint32_t point_count;
} outline_expect_t;

static const uint16_t DOT_ENDS[] = {11};
static const exp_point_t DOT_PTS[] = {
    {300, -10, 1}, {263, -10, 0}, {218, 34, 0}, {218, 69, 1}, {218, 106, 0}, {263, 152, 0},
    {300, 152, 1}, {337, 152, 0}, {382, 106, 0}, {382, 69, 1}, {382, 34, 0}, {337, -10, 0},
};

static const uint16_t A_ENDS[] = {7, 16};
static const exp_point_t A_PTS[] = {
    {50, 0, 1}, {240, 730, 1}, {361, 730, 1}, {550, 0, 1}, {459, 0, 1}, {411, 194, 1},
    {190, 194, 1}, {142, 0, 1}, {208, 270, 1}, {392, 270, 1}, {336, 495, 1}, {320, 559, 0},
    {302, 645, 0}, {300, 658, 1}, {298, 645, 0}, {280, 559, 0}, {264, 496, 1},
};

static const uint16_t ALOWER_ENDS[] = {27, 38, 42};
static const exp_point_t ALOWER_PTS[] = {
    {252, -10, 1}, {167, -10, 0}, {67, 85, 0}, {67, 162, 1}, {67, 213, 0}, {113, 289, 0},
    {195, 332, 0}, {248, 332, 1}, {418, 332, 1}, {418, 375, 1}, {418, 482, 0}, {301, 482, 1},
    {249, 482, 0}, {185, 444, 0}, {183, 410, 1}, {93, 410, 1}, {98, 475, 0}, {209, 560, 0},
    {301, 560, 1}, {401, 560, 0}, {508, 464, 0}, {508, 378, 1}, {508, 0, 1}, {419, 0, 1},
    {419, 100, 1}, {417, 100, 1}, {409, 49, 0}, {323, -10, 0}, {274, 66, 1}, {340, 66, 0},
    {418, 130, 0}, {418, 185, 1}, {418, 262, 1}, {258, 262, 1}, {214, 262, 0}, {159, 209, 0},
    {159, 165, 1}, {159, 119, 0}, {220, 66, 0}, {247, 645, 1}, {353, 785, 1}, {450, 785, 1},
    {339, 645, 1},
};

static const outline_expect_t OUTLINE_EXPECTED[] = {
    {0x002E, 908, DOT_ENDS, 1, DOT_PTS, 12},
    {0x0041, 1, A_ENDS, 2, A_PTS, 17},
    {0x0061, 199, ALOWER_ENDS, 3, ALOWER_PTS, 43},
};

static int32_t unscale(q48_16_t q) {
    return (int32_t) (((int64_t) q) >> 16);
}

static void test_outlines(const ttf_font_t *font) {
    ttf_point_t point_buf[600];
    uint16_t contour_buf[16];
    size_t i;

    for (i = 0; i < sizeof(OUTLINE_EXPECTED) / sizeof(OUTLINE_EXPECTED[0]); i++) {
        const outline_expect_t *e = &OUTLINE_EXPECTED[i];
        ttf_outline_t outline;
        int rc;
        uint32_t j;

        outline.points = point_buf;
        outline.max_points = sizeof(point_buf) / sizeof(point_buf[0]);
        outline.contour_ends = contour_buf;
        outline.max_contours = sizeof(contour_buf) / sizeof(contour_buf[0]);

        rc = ttf_glyph_outline(font, e->glyph, &outline);
        if (rc != TTF_OK) {
            printf("  FAIL U+%04X ttf_glyph_outline rc=%d\n", e->codepoint, rc);
            failures++;
            continue;
        }

        printf("U+%04X outline: points=%u (want %u) contours=%u (want %u)\n",
               e->codepoint, outline.point_count, e->point_count,
               outline.contour_count, e->contour_count);
        check_eq_i("point_count", e->codepoint, outline.point_count, e->point_count);
        check_eq_i("contour_count", e->codepoint, outline.contour_count, e->contour_count);

        for (j = 0; j < e->contour_count && j < outline.contour_count; j++) {
            check_eq_i("contour_end", e->codepoint, outline.contour_ends[j], e->contour_ends[j]);
        }
        for (j = 0; j < e->point_count && j < outline.point_count; j++) {
            check_eq_i("point.x", e->codepoint, unscale(outline.points[j].x), e->points[j].x);
            check_eq_i("point.y", e->codepoint, unscale(outline.points[j].y), e->points[j].y);
            check_eq_i("point.on_curve", e->codepoint, outline.points[j].on_curve, e->points[j].on_curve);
        }
    }
}

/* Rasterization (4.3.7c) sanity check: rasterize a glyph at a modest
 * pixel size, print an ASCII-art dump for visual "is this recognizable"
 * inspection (this item's own acceptance criterion), plus loose
 * structural checks -- fill coverage in a plausible range, background
 * untouched in the far corner -- since there's no independent reference
 * rasterizer to diff against pixel-for-pixel (unlike 4.3.7/4.3.7a, which
 * had a from-scratch Python decoder to check against). */
static void test_rasterize(const ttf_font_t *font, uint32_t codepoint, const char *label) {
    enum { SIZE_PX = 28, MARGIN = 6 };
    uint32_t w = SIZE_PX + MARGIN * 2;
    uint32_t h = SIZE_PX + MARGIN * 2;
    uint8_t *pixels = calloc((size_t) w * h, 1);
    ttf_bitmap_t bmp;
    q48_16_t scale;
    uint32_t gid;
    int rc;
    uint32_t x, y, filled = 0;

    if (!pixels) {
        printf("test_rasterize U+%04X: calloc failed\n", codepoint);
        failures++;
        return;
    }

    bmp.pixels = pixels;
    bmp.width = w;
    bmp.height = h;

    scale = q48_div(q48_from_u64(SIZE_PX), q48_from_u64(font->units_per_em));
    gid = ttf_codepoint_to_glyph(font, codepoint);

    rc = ttf_rasterize_glyph(font, gid, scale,
                              q48_from_u64(MARGIN),
                              q48_from_u64(SIZE_PX + MARGIN),
                              255, &bmp);
    if (rc != TTF_OK) {
        printf("test_rasterize U+%04X (%s): ttf_glyph_outline/rasterize rc=%d\n",
               codepoint, label, rc);
        failures++;
        free(pixels);
        return;
    }

    printf("U+%04X (%s) rasterized %ux%u:\n", codepoint, label, w, h);
    for (y = 0; y < h; y++) {
        putchar('|');
        for (x = 0; x < w; x++) {
            int on = pixels[y * w + x] != 0;
            putchar(on ? '#' : '.');
            if (on) filled++;
        }
        putchar('|');
        putchar('\n');
    }
    printf("  filled=%u / %u px (%.1f%%)\n", filled, w * h, 100.0 * filled / (w * h));

    if (filled == 0) {
        printf("  FAIL U+%04X (%s): rasterized to nothing\n", codepoint, label);
        failures++;
    } else if (filled > (w * h * 3) / 4) {
        printf("  FAIL U+%04X (%s): implausibly full (%u/%u px) -- looks like a fill-rule bug\n",
               codepoint, label, filled, w * h);
        failures++;
    }
    if (pixels[0] != 0) {
        printf("  FAIL U+%04X (%s): top-left corner (background) is filled\n", codepoint, label);
        failures++;
    }

    free(pixels);
}

int main(int argc, char **argv) {
    FILE *fp;
    long size;
    uint8_t *buf;
    ttf_font_t font;
    int rc;
    size_t i;

    if (argc < 2) {
        fprintf(stderr, "usage: %s <path-to-ttf>\n", argv[0]);
        return 2;
    }

    fp = fopen(argv[1], "rb");
    if (!fp) {
        perror("fopen");
        return 2;
    }
    fseek(fp, 0, SEEK_END);
    size = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    buf = malloc((size_t) size);
    if (!buf || fread(buf, 1, (size_t) size, fp) != (size_t) size) {
        fprintf(stderr, "read failed\n");
        return 2;
    }
    fclose(fp);

    rc = ttf_parse(buf, (uint32_t) size, &font);
    if (rc != TTF_OK) {
        printf("ttf_parse failed: rc=%d\n", rc);
        return 1;
    }
    printf("parsed: unitsPerEm=%u numGlyphs=%u indexToLocFormat=%d has_cmap=%d\n",
           font.units_per_em, font.num_glyphs, font.index_to_loc_format, font.has_cmap);

    for (i = 0; i < sizeof(EXPECTED) / sizeof(EXPECTED[0]); i++) {
        const expect_t *e = &EXPECTED[i];
        uint32_t gid = ttf_codepoint_to_glyph(&font, e->codepoint);
        ttf_glyph_header_t hdr;
        int hrc;

        printf("U+%04X -> glyph %u (want %u)\n", e->codepoint, gid, e->expect_glyph);
        check_eq_i("glyph", e->codepoint, gid, e->expect_glyph);

        hrc = ttf_glyph_header(&font, gid, &hdr);
        if (hrc != TTF_OK) {
            printf("  FAIL U+%04X ttf_glyph_header rc=%d\n", e->codepoint, hrc);
            failures++;
            continue;
        }
        check_eq_i("num_contours", e->codepoint, hdr.num_contours, e->expect_contours);
        check_eq_i("x_min", e->codepoint, hdr.x_min, e->expect_xmin);
        check_eq_i("y_min", e->codepoint, hdr.y_min, e->expect_ymin);
        check_eq_i("x_max", e->codepoint, hdr.x_max, e->expect_xmax);
        check_eq_i("y_max", e->codepoint, hdr.y_max, e->expect_ymax);
        check_eq_i("glyf_offset", e->codepoint, hdr.glyf_offset, e->expect_glyf_offset);
        check_eq_i("glyf_length", e->codepoint, hdr.glyf_length, e->expect_glyf_length);
    }

    test_outlines(&font);

    test_rasterize(&font, 0x0041, "'A'");
    test_rasterize(&font, 0x002E, "'.'");
    test_rasterize(&font, 0x0061, "'a'");

    free(buf);

    if (failures) {
        printf("%d check(s) FAILED\n", failures);
        return 1;
    }
    printf("all checks passed\n");
    return 0;
}