/* Побайтовый регресс gfx_scroll_h/gfx_scroll_v.
 * Источник — неактивная page 1, приёмник — draw page 0. */
#include <graphics.h>
#include <gfx.h>
#include <sprite.h>

#define AX  10
#define AY  24
#define AW 300                 /* проверяет разбиение ширины 255+45 */
#define AH 160
#define DIRT 0x31

static uint8_t pattern(int x, int y)
{
    return (uint8_t)(0x40 + ((x * 3 + y * 5) & 0x3f));
}

static void draw_source(void)
{
    int x, y;
    for (y = AY; y < AY + AH; y++)
        for (x = AX; x < AX + AW; x++)
            putpixel(x, y, pattern(x, y));
}

static void clear_target(void)
{
    setfillstyle(SOLID_FILL, DIRT);
    bar(0, 0, 319, 255);
}

static uint8_t rect_eq(const gfx_rect_t *r, int x, int y, int w, int h)
{
    return r->x == x && r->y == y && r->w == w && r->h == h;
}

static uint8_t check_h(int dx)
{
    gfx_rect_t a = { AX, AY, AW, AH }, d;
    int x, y, sx;

    clear_target();
    gfx_scroll_h(&a, dx, &d);
    if (dx > 0) {
        if (!rect_eq(&d, AX, AY, dx, AH)) return 0;
    } else if (dx < 0) {
        if (!rect_eq(&d, AX + AW + dx, AY, -dx, AH)) return 0;
    } else if (!rect_eq(&d, AX, AY, 0, AH)) return 0;

    for (y = AY; y < AY + AH; y++)
        for (x = AX; x < AX + AW; x++) {
            sx = x - dx;
            if (sx >= AX && sx < AX + AW) {
                if ((uint8_t)getpixel(x, y) != pattern(sx, y)) return 0;
            } else if ((uint8_t)getpixel(x, y) != DIRT) return 0;
        }
    return 1;
}

static uint8_t check_v(int dy)
{
    gfx_rect_t a = { AX, AY, AW, AH }, d;
    int x, y, sy;

    clear_target();
    gfx_scroll_v(&a, dy, &d);
    if (dy > 0) {
        if (!rect_eq(&d, AX, AY, AW, dy)) return 0;
    } else if (!rect_eq(&d, AX, AY + AH + dy, AW, -dy)) return 0;

    for (y = AY; y < AY + AH; y++)
        for (x = AX; x < AX + AW; x++) {
            sy = y - dy;
            if (sy >= AY && sy < AY + AH) {
                if ((uint8_t)getpixel(x, y) != pattern(x, sy)) return 0;
            } else if ((uint8_t)getpixel(x, y) != DIRT) return 0;
        }
    return 1;
}

static uint8_t check_limits(void)
{
    gfx_rect_t a = { -5, -7, 25, 27 }, d;
    gfx_scroll_h(&a, 40, &d);
    if (!rect_eq(&d, 0, 0, 20, 20)) return 0;
    gfx_scroll_v(&a, -40, &d);
    return rect_eq(&d, 0, 0, 20, 20);
}

static uint8_t check_source(void)
{
    int x, y;
    gfx_set_draw_page(1);
    for (y = AY; y < AY + AH; y++)
        for (x = AX; x < AX + AW; x++)
            if ((uint8_t)getpixel(x, y) != pattern(x, y)) {
                gfx_set_draw_page(0);
                return 0;
            }
    gfx_set_draw_page(0);
    return 1;
}

static void say(int y, const char *name, uint8_t ok)
{
    setcolor(WHITE); outtextxy(8, y, (char *)name);
    setcolor(ok ? GREEN : RED); outtextxy(232, y, ok ? (char *)"PASS" : (char *)"FAIL");
}

void main(void)
{
    uint8_t t[7], i;

    initgraph();
    gfx_set_bank(GFX_BANK_NORMAL);
    gfx_set_draw_page(1); draw_source();
    gfx_set_draw_page(0);

    t[0] = check_h(8);
    t[1] = check_h(-13);
    t[2] = check_v(9);
    t[3] = check_v(-11);
    t[4] = check_limits();
    t[5] = check_h(0);
    t[6] = check_source();

    clear_target();
    say(40,  "H +8, wide", t[0]);
    say(56,  "H -13, wide", t[1]);
    say(72,  "V +9, wide", t[2]);
    say(88,  "V -11, wide", t[3]);
    say(104, "clip/full dirty", t[4]);
    say(120, "H zero/full copy", t[5]);
    say(136, "source intact", t[6]);
    for (i = 0; i < 7 && t[i]; i++) { }
    setcolor(WHITE);
    outtextxy(8, 160, i == 7 ? (char *)"ALL PASS" : (char *)"SOME FAILED");
    for (;;) { }
}