power_play/src/font.c

#include "font.h"
#include "arena.h"
#include "ttf.h"
#include "work.h"
#include "scratch.h"
#include "asset_cache.h"
#include "resource.h"
#include "log.h"
#include "string.h"

#define FONT_CHARS " !\"#$%&\'()-.,*/0123456789:;<=+>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
#define LOOKUP_TABLE_SIZE (256)

struct font_task_params {
    struct font_task_params *next_free;

    struct asset *asset;
    f32 point_size;
    u64 path_len;
    char path_cstr[1024];
};

struct font_task_params_store {
    struct font_task_params *head_free;
    struct arena arena;
    struct sys_mutex mutex;
};

/* ========================== *
 * Global state
 * ========================== */

GLOBAL struct {
    struct font_task_params_store params;
} L = { 0 }, DEBUG_LVAR(L_font);

/* ========================== *
 * Startup
 * ========================== */

void font_startup(void)
{
    L.params.arena = arena_alloc(GIGABYTE(64));
    L.params.mutex = sys_mutex_alloc();
}

/* ========================== *
 * Load task param store
 * ========================== */

INTERNAL struct font_task_params *font_task_params_alloc(void)
{
    struct font_task_params *p = NULL;
    {
        sys_mutex_lock(&L.params.mutex);
        if (L.params.head_free) {
            p = L.params.head_free;
            L.params.head_free = p->next_free;
        } else {
            p = arena_push_zero(&L.params.arena, struct font_task_params);
        }
        sys_mutex_unlock(&L.params.mutex);
    }
    return p;
}

INTERNAL void font_task_params_release(struct font_task_params *p)
{
    sys_mutex_lock(&L.params.mutex);
    p->next_free = L.params.head_free;
    L.params.head_free = p;
    sys_mutex_unlock(&L.params.mutex);
}

/* ========================== *
 * Load
 * ========================== */

INTERNAL void font_load_asset_task(void *vparams)
{
    __prof;
    struct font_task_params *params = (struct font_task_params *)vparams;
    struct temp_arena scratch = scratch_begin_no_conflict();
    struct string path = string_from_cstr_len(params->path_cstr, params->path_len);
    f32 point_size = params->point_size;
    struct asset *asset = params->asset;

    logf_info("Loading font \"%F\" (point size %F)", FMT_STR(path), FMT_FLOAT((f64)point_size));
    sys_timestamp_t start_ts = sys_timestamp();

    ASSERT(string_ends_with(path, STR(".ttf")));
    if (!resource_exists(path)) {
        /* TODO: Load baked font instead of panicking */
        sys_panic(string_format(scratch.arena,
                                STR("Font \"%F\" not found"),
                                FMT_STR(path)));
    }

    struct string font_chars = STR(FONT_CHARS);

    /* Decode */
    struct resource res = resource_open(path);
    struct ttf_decode_result result = ttf_decode(scratch.arena, res.bytes, point_size, font_chars);
    resource_close(res);

    /* Send texture to GPU */
    struct renderer_handle texture_renderer_handle = renderer_texture_alloc(result.image_data);

    /* Allocate store memory */
    struct font *font = NULL;
    {
        struct asset_cache_store store = asset_cache_store_open();
        font = arena_push_zero(store.arena, struct font);
        font->glyphs = arena_push_array(store.arena, struct font_glyph, result.glyphs_count);
        font->lookup = arena_push_array_zero(store.arena, u16, LOOKUP_TABLE_SIZE);
        asset_cache_store_close(&store);
    }

    /* Set font data */
    font->texture = (struct texture) {
        .renderer_handle = texture_renderer_handle,
        .width = result.image_data.width,
        .height = result.image_data.height
    };
    font->glyphs_count = result.glyphs_count;
    font->point_size = point_size;

    /* Copy glyphs from decode result */
    MEMCPY(font->glyphs, result.glyphs, sizeof(*font->glyphs) * result.glyphs_count);

    /* Build lookup table */
    for (u64 i = 0; i < font_chars.len; ++i) {
        u8 c = font_chars.text[i];
        font->lookup[c] = result.cache_indices[i];
    }

    font_task_params_release(params);

    logf_info("Finished loading font \"%F\" (point size %F) in %F seconds", FMT_STR(path), FMT_FLOAT((f64)point_size), FMT_FLOAT(sys_timestamp_seconds(sys_timestamp() - start_ts)));
    asset_cache_mark_ready(asset, font);

    scratch_end_and_decommit(scratch);
}

/* Returns the asset from the asset cache */
struct asset *font_load_asset(struct string path, f32 point_size, b32 help)
{
    __prof;
    struct temp_arena scratch = scratch_begin_no_conflict();

    /* Concatenate point_size to path for key */
    struct string key = string_format(scratch.arena,
                                      STR("%F%F_font"),
                                      FMT_STR(path),
                                      FMT_FLOAT_P((f64)point_size, 3));
    u64 hash = asset_cache_hash(key);
    b32 is_first_touch;
    struct asset *asset = asset_cache_touch(key, hash, &is_first_touch);

    if (is_first_touch) {
        /* Assemble task params */
        struct font_task_params *params = font_task_params_alloc();
        if (path.len > (sizeof(params->path_cstr) - 1)) {
            sys_panic(string_format(scratch.arena,
                                    STR("Font path \"%F\" too long!"),
                                    FMT_STR(path)));
        }
        string_to_cstr_buff(path, BUFFER_FROM_ARRAY(params->path_cstr));
        params->path_len = path.len;
        params->asset = asset;
        params->point_size = point_size;

        /* Push task */
        asset_cache_mark_loading(asset);
        struct work_handle wh = { 0 };
        if (help) {
            wh = work_push_task_and_help(&font_load_asset_task, params, WORK_PRIORITY_NORMAL);
        } else {
            wh = work_push_task(&font_load_asset_task, params, WORK_PRIORITY_NORMAL);
        }
        asset_cache_set_work(asset, &wh);
    }

    scratch_end(scratch);
    return asset;
}

struct font *font_load_async(struct string path, f32 point_size)
{
    __prof;
    struct asset *asset = font_load_asset(path, point_size, false);
    struct font *f = (struct font *)asset_cache_get_store_data(asset);
    return f;
}

struct font *font_load(struct string path, f32 point_size)
{
    __prof;
    struct asset *asset = font_load_asset(path, point_size, true);
    asset_cache_wait(asset);
    struct font *f = (struct font *)asset_cache_get_store_data(asset);
    return f;
}

/* ========================== *
 * Other
 * ========================== */

struct font_glyph *font_get_glyph(struct font *font, u8 c)
{
    struct font_glyph *g;
    u16 index = font->lookup[c];
    if (index < LOOKUP_TABLE_SIZE) {
        g = &font->glyphs[index];
    } else {
        g = &font->glyphs[0];
    }
    return g;
}