SchOS/boot/common/ui.c

/* SPDX-License-Identifier: Apache-2.0 */
/*
 * The loader's user interface. See ui.h for why this can be shared at all.
 *
 * The look is deliberately quiet: a dark ground, the mark centred, one thin
 * bar beneath it, and no text that is not load-bearing. A loader is not a
 * place to be interesting -- it is looked at for four seconds by someone who
 * wants to be somewhere else, and the useful thing it can do is stay still and
 * tell them it is working.
 */

#include "ui.h"
#include "../../include/theme.h"
#include "../../include/font.h"
#include "../../include/logo.h"

/* "Draw the glyph, leave the background alone." Not a colour anyone can mean:
 * the palette is 24-bit, so the high byte is free for a sentinel. */
#define SCH_BG_NONE 0xFF000000u

static struct ui_fb FB;
static int          ACTIVE;

/* Progress state. Kept here rather than passed around because the caller ticks
 * it from inside a read loop that has no business carrying UI state. */
static ui_u32 PROG_TOTAL, PROG_DONE;
static int    PROG_X, PROG_Y, PROG_W, PROG_H;
static int    PROG_LAST_PX;             /* pixels already filled */
static int    PROG_ACTIVE;

/* Layout constants. One place, because a splash that is laid out by scattered
 * literals is one nobody dares move.
 *
 * The mark and the bar are the same width, and that is the arrangement: a small
 * mark with a short bar directly beneath it, both centred. Everything else --
 * gaps, panel sizes -- is expressed against that width so the whole thing
 * scales as one object.
 */
#define MARK_W_FRAC     8       /* the mark is width/8 ... */
#define MARK_W_MIN      72      /* ... clamped, because a mark that tracks the */
#define MARK_W_MAX      128     /* mode exactly is tiny at 800 and soft at 1600 */
#define MARK_GAP        30      /* mark bottom to the bar */
#define SUB_GAP         20      /* bar to the line under it */
#define BAR_H           4       /* thin: it is a hint, not a gauge */
#define GLYPH_W         8
#define GLYPH_H         16

/* --- the metal ------------------------------------------------------------
 *
 * Brushed metal, done the cheap way that actually survives a 4-bit mask and a
 * 32bpp framebuffer: a vertical gradient from a light top to a darker bottom,
 * with a brighter band near the top where a highlight would fall. There is no
 * texture and no noise -- at this size they read as dirt rather than as metal,
 * and the loader has no business carrying a texture asset.
 *
 * The mark is not a flat colour any more for the same reason a real one would
 * not be: a single grey on a dark ground looks printed, and the gradient is
 * what makes it look like an object with a light above it.
 */
#define METAL_TOP       0xF2F4F8u   /* near-white, where the light lands */
#define METAL_MID       0xB9BEC7u
#define METAL_BOT       0x6E747Fu   /* shadowed underside */
#define METAL_EDGE      0x3A3F49u   /* panel border */
#define PANEL_BG        0x151821u   /* panel ground, a shade off SCH_BG */
#define PANEL_TOP       0x232838u   /* bevel: one row lighter along the top */

static ui_u32
mix(ui_u32 a, ui_u32 b, int num, int den)
{
    if (den <= 0) return a;
    if (num < 0) num = 0;
    if (num > den) num = den;
    ui_u32 r = ((((a >> 16) & 0xFF) * (den - num)) + (((b >> 16) & 0xFF) * num)) / den;
    ui_u32 g = ((((a >>  8) & 0xFF) * (den - num)) + (((b >>  8) & 0xFF) * num)) / den;
    ui_u32 bl = ((((a      ) & 0xFF) * (den - num)) + (((b      ) & 0xFF) * num)) / den;
    return (r << 16) | (g << 8) | bl;
}

/* The metal colour at row `i` of an object `h` rows tall. */
static ui_u32
metal(int i, int h)
{
    if (h <= 1)
        return METAL_MID;
    /* Two segments: a fast lift into the highlight over the top third, then a
     * long fall to the shadow. A single linear ramp looks like a gradient; the
     * knee is what makes it look lit. */
    int knee = h / 3;
    if (i <= knee)
        return mix(METAL_MID, METAL_TOP, i, knee ? knee : 1);
    return mix(METAL_TOP, METAL_BOT, i - knee, h - knee);
}

void
ui_init(const struct ui_fb *fb)
{
    ACTIVE = 0;
    if (!fb || !fb->base || !fb->width || !fb->height)
        return;
    FB = *fb;
    if (!FB.stride)
        FB.stride = FB.width * 4;
    ACTIVE = 1;
}

int    ui_active(void) { return ACTIVE; }
ui_u32 ui_width(void)  { return ACTIVE ? FB.width  : 0; }
ui_u32 ui_height(void) { return ACTIVE ? FB.height : 0; }

static void
put(int x, int y, ui_u32 colour)
{
    if (!ACTIVE || x < 0 || y < 0 || (ui_u32)x >= FB.width || (ui_u32)y >= FB.height)
        return;
    *(ui_u32 *)(FB.base + (ui_u64)y * FB.stride + (ui_u64)x * 4) = colour;
}

void
ui_fill_rect(int x, int y, int w, int h, ui_u32 colour)
{
    if (!ACTIVE)
        return;
    for (int r = 0; r < h; r++) {
        int yy = y + r;
        if (yy < 0 || (ui_u32)yy >= FB.height)
            continue;
        /* One row at a time through a row pointer: put() per pixel costs a
         * bounds check and a multiply for every one of them, and this is used
         * to clear a whole screen. */
        ui_u32 *row = (ui_u32 *)(FB.base + (ui_u64)yy * FB.stride);
        for (int c = 0; c < w; c++) {
            int xx = x + c;
            if (xx >= 0 && (ui_u32)xx < FB.width)
                row[xx] = colour;
        }
    }
}

void
ui_clear(void)
{
    ui_fill_rect(0, 0, (int)FB.width, (int)FB.height, SCH_BG);
}

static void
glyph(int x, int y, ui_u8 c, ui_u32 colour, ui_u32 bg)
{
    for (int row = 0; row < GLYPH_H; row++) {
        ui_u8 bits = font_data[c][row];
        for (int col = 0; col < GLYPH_W; col++) {
            if (bits & (0x80 >> col))
                put(x + col, y + row, colour);
            else if (bg != SCH_BG_NONE)
                put(x + col, y + row, bg);
        }
    }
}

void
ui_text(int x, int y, const char *s, ui_u32 colour, ui_u32 bg)
{
    if (!ACTIVE || !s)
        return;
    for (int i = 0; s[i]; i++)
        glyph(x + i * GLYPH_W, y, (ui_u8)s[i], colour, bg);
}

static int
slen(const char *s)
{
    int n = 0;
    while (s && s[n])
        n++;
    return n;
}

void
ui_text_centered(int y, const char *s, ui_u32 colour)
{
    if (!ACTIVE)
        return;
    int w = slen(s) * GLYPH_W;
    ui_text(((int)FB.width - w) / 2, y, s, colour, SCH_BG_NONE);
}

int
ui_mark_width(void)
{
    if (!ACTIVE)
        return MARK_W_MIN;
    int w = (int)FB.width / MARK_W_FRAC;
    if (w < MARK_W_MIN) w = MARK_W_MIN;
    if (w > MARK_W_MAX) w = MARK_W_MAX;
    return w;
}

void
ui_logo(int y, int w)
{
    if (!ACTIVE)
        return;
    if (w <= 0 || w > LOGO_W)
        w = LOGO_W;                     /* never upscale: it only goes soft */

    int h  = (LOGO_H * w) / LOGO_W;
    int x0 = ((int)FB.width - w) / 2;

    /* Box-filter down from the source mask.
     *
     * Point-sampling a coverage mask drops half the edge pixels and gives a
     * mark with holes in the thin strokes -- exactly where a logo can least
     * afford them. Averaging the coverage of every source pixel that lands in a
     * destination pixel is what keeps the shape intact at 72 px.
     */
    for (int dy = 0; dy < h; dy++) {
        int sy0 = (dy * LOGO_H) / h, sy1 = ((dy + 1) * LOGO_H) / h;
        if (sy1 <= sy0) sy1 = sy0 + 1;

        ui_u32 shade = metal(dy, h);

        for (int dx = 0; dx < w; dx++) {
            int sx0 = (dx * LOGO_W) / w, sx1 = ((dx + 1) * LOGO_W) / w;
            if (sx1 <= sx0) sx1 = sx0 + 1;

            unsigned sum = 0, n = 0;
            for (int sy = sy0; sy < sy1; sy++) {
                for (int sx = sx0; sx < sx1; sx++) {
                    unsigned idx = (unsigned)sy * LOGO_W + (unsigned)sx;
                    sum += (logo_mask[idx >> 1] >> ((idx & 1) ? 0 : 4)) & 0xF;
                    n++;
                }
            }
            unsigned cov = n ? sum / n : 0;
            if (!cov)
                continue;

            /* Coverage blends the shaded metal against the ground, so the mark
             * has soft edges and a lit face at the same time. */
            put(x0 + dx, y + dy, mix(SCH_BG, shade, (int)cov, 15));
        }
    }
}

/* Where the bar goes. Derived, not stored, so nothing can set it and then have
 * the screen change underneath it.
 *
 * The bar is exactly the mark's width and sits directly beneath it: the two are
 * one object, and a bar wider than the mark it belongs to reads as a separate
 * thing that happens to be nearby.
 */
static void
bar_geometry(void)
{
    PROG_W = ui_mark_width();
    PROG_H = BAR_H;
    PROG_X = ((int)FB.width - PROG_W) / 2;

    int mark_h  = (LOGO_H * PROG_W) / LOGO_W;
    int group_h = mark_h + MARK_GAP + PROG_H;
    int top     = ((int)FB.height - group_h) / 2;
    PROG_Y = top + mark_h + MARK_GAP;
}

void
ui_splash(const char *subtitle)
{
    if (!ACTIVE)
        return;

    ui_clear();
    bar_geometry();

    int w      = PROG_W;
    int mark_h = (LOGO_H * w) / LOGO_W;
    int top    = PROG_Y - MARK_GAP - mark_h;

    ui_logo(top, w);

    if (subtitle)
        ui_text_centered(PROG_Y + PROG_H + SUB_GAP, subtitle, SCH_DIM);
}

/* --- panels ---------------------------------------------------------------
 *
 * A panel is a plate: a slightly lighter ground than the screen, one lighter
 * row along the top and a darker border, which is the whole of the bevel. Two
 * rows of shading do more for the impression of a raised surface than any
 * amount of gradient inside it, and cost nothing to draw.
 */
static void
panel(int x, int y, int w, int h)
{
    ui_fill_rect(x, y, w, h, PANEL_BG);
    ui_fill_rect(x, y, w, 1, PANEL_TOP);                /* lit top edge */
    ui_fill_rect(x, y + h - 1, w, 1, METAL_EDGE);       /* shadowed bottom */
    ui_fill_rect(x, y, 1, h, METAL_EDGE);
    ui_fill_rect(x + w - 1, y, 1, h, METAL_EDGE);
}

/* A heading in metal: the same shading the mark uses, applied per row of the
 * glyph cell, so a title looks struck out of the same material. */
static void
metal_text_centered(int y, const char *s)
{
    int len = slen(s);
    int x   = ((int)FB.width - len * GLYPH_W) / 2;

    for (int row = 0; row < GLYPH_H; row++) {
        ui_u32 shade = metal(row, GLYPH_H);
        for (int i = 0; i < len; i++) {
            ui_u8 bits = font_data[(ui_u8)s[i]][row];
            for (int col = 0; col < GLYPH_W; col++)
                if (bits & (0x80 >> col))
                    put(x + i * GLYPH_W + col, y + row, shade);
        }
    }
}

/* Panel metrics.
 *
 * TITLE_H is the whole title band -- the padding above the heading, the
 * heading itself, and the air beneath it before the rule. It was 34 while the
 * heading alone needs 18 + 16 = 34, so the rule at TITLE_H - 6 was drawn
 * *through* the lettering and the first row started on the heading's baseline.
 * Derived from its parts now, so it cannot drift from them again.
 */
#define ROW_H       24
#define PANEL_PAD   18
#define TITLE_GAP   14                                  /* heading to the rule */
#define TITLE_H     (PANEL_PAD + GLYPH_H + TITLE_GAP)   /* = 48 */
#define ROW_LIFT    ((ROW_H - GLYPH_H) / 2)              /* highlight overhang */

static void
panel_frame(const char *title, int rows, const char *hint,
            int *out_x, int *out_y, int *out_w)
{
    int w = (int)FB.width / 2;
    if (w < 360) w = 360;
    if (w > (int)FB.width - 60) w = (int)FB.width - 60;

    int h = TITLE_H + rows * ROW_H + PANEL_PAD * 2;
    int x = ((int)FB.width - w) / 2;
    int y = ((int)FB.height - h) / 2;

    ui_clear();

    /* The mark, small, above the plate: it is the same screen, not a new one. */
    int mw = ui_mark_width() * 2 / 3;
    int mh = (LOGO_H * mw) / LOGO_W;
    if (y - mh - 24 > 0)
        ui_logo(y - mh - 24, mw);

    panel(x, y, w, h);
    metal_text_centered(y + PANEL_PAD, title);
    ui_fill_rect(x + PANEL_PAD, y + PANEL_PAD + GLYPH_H + TITLE_GAP / 2,
                 w - PANEL_PAD * 2, 1, METAL_EDGE);

    if (hint)
        ui_text_centered(y + h + 16, hint, SCH_DIM);

    *out_x = x; *out_y = y + TITLE_H; *out_w = w;
}

void
ui_menu(const char *title, const char *const *items, int n, int selected,
        const char *hint)
{
    if (!ACTIVE)
        return;

    int x, y, w;
    panel_frame(title, n, hint, &x, &y, &w);

    for (int i = 0; i < n; i++) {
        int ry = y + i * ROW_H;

        if (i == selected) {
            /* The selected row is the only lit thing on the plate. Filling it
             * with the accent and putting the label in the ground colour reads
             * at a glance; an outline does not, at this size. */
            /* Centred on the glyph box: (ROW_H - GLYPH_H) / 2 above it, the
             * same below. Off-by-a-few here is what makes a highlight look
             * like it is sitting on the text rather than around it. */
            ui_fill_rect(x + PANEL_PAD / 2, ry - ROW_LIFT, w - PANEL_PAD, ROW_H,
                         SCH_ACCENT);
            ui_text(x + PANEL_PAD, ry, items[i], PANEL_BG, SCH_BG_NONE);
        } else {
            ui_text(x + PANEL_PAD, ry, items[i], SCH_FG, SCH_BG_NONE);
        }
    }
}

void
ui_panel(const char *title, const char *const *labels,
         const char *const *values, int n, const char *hint)
{
    if (!ACTIVE)
        return;

    int x, y, w;
    panel_frame(title, n, hint, &x, &y, &w);

    for (int i = 0; i < n; i++) {
        int ry = y + i * ROW_H;
        ui_text(x + PANEL_PAD, ry, labels[i], SCH_DIM, SCH_BG_NONE);

        /* Values right-aligned, so the column reads down rather than ragged. */
        int vw = slen(values[i]) * GLYPH_W;
        ui_text(x + w - PANEL_PAD - vw, ry, values[i], SCH_FG, SCH_BG_NONE);
    }
}

void
ui_progress_begin(const char *label, ui_u32 total)
{
    if (!ACTIVE)
        return;

    bar_geometry();
    PROG_TOTAL   = total ? total : 1;
    PROG_DONE    = 0;
    PROG_LAST_PX = 0;
    PROG_ACTIVE  = 1;

    /* The unfilled track: a recess, not a colour. Drawn once -- repainting it
     * on every tick is what makes a progress bar flicker. */
    ui_fill_rect(PROG_X, PROG_Y, PROG_W, PROG_H, 0x1B1F28u);
    ui_fill_rect(PROG_X, PROG_Y, PROG_W, 1, 0x101319u);
    if (label)
        ui_progress_label(label);
}

void
ui_progress_label(const char *label)
{
    if (!ACTIVE || !label)
        return;

    /* Clear the line first. A shorter label after a longer one would otherwise
     * leave the tail of the old one behind. */
    int y = PROG_Y + PROG_H + SUB_GAP;
    ui_fill_rect(0, y, (int)FB.width, GLYPH_H, SCH_BG);
    ui_text_centered(y, label, SCH_DIM);
}

void
ui_progress_tick(ui_u32 done)
{
    if (!ACTIVE || !PROG_ACTIVE)
        return;

    if (done > PROG_TOTAL)
        done = PROG_TOTAL;
    PROG_DONE = done;

    int px = (int)(((ui_u64)PROG_DONE * (ui_u64)PROG_W) / PROG_TOTAL);

    /* Only the newly filled part. Filling from zero each time is O(width) per
     * tick and visibly slower than the thing it is reporting on. */
    if (px > PROG_LAST_PX) {
        /* The fill is metal too, shaded across the bar's height, so it looks
         * like the same material as the mark rather than a coloured rectangle
         * that happens to be underneath it. */
        for (int r = 0; r < PROG_H; r++)
            ui_fill_rect(PROG_X + PROG_LAST_PX, PROG_Y + r,
                         px - PROG_LAST_PX, 1, metal(r, PROG_H));
        PROG_LAST_PX = px;
    }
}

void
ui_progress_end(void)
{
    if (!ACTIVE || !PROG_ACTIVE)
        return;
    ui_progress_tick(PROG_TOTAL);
    PROG_ACTIVE = 0;
}