raddebugger/src/font_cache/font_cache.h

// Copyright (c) 2024 Epic Games Tools
// Licensed under the MIT license (https://opensource.org/license/mit/)

#ifndef FONT_CACHE_H
#define FONT_CACHE_H

////////////////////////////////
//~ rjf: Rasterization Flags

typedef U32 F_RunFlags;
enum
{
  F_RunFlag_Smooth = (1<<0),
};

////////////////////////////////
//~ rjf: Handles & Tags

typedef struct F_Hash F_Hash;
struct F_Hash
{
  U64 u64[2];
};

typedef struct F_Tag F_Tag;
struct F_Tag
{
  U64 u64[2];
};

////////////////////////////////
//~ rjf: Draw Package Types (For Cache Queries)

typedef struct F_Piece F_Piece;
struct F_Piece
{
  R_Handle texture;
  Rng2S16 subrect;
  Vec2S16 offset;
  F32 advance;
  U16 decode_size;
};

typedef struct F_PieceChunkNode F_PieceChunkNode;
struct F_PieceChunkNode
{
  F_PieceChunkNode *next;
  F_Piece *v;
  U64 count;
  U64 cap;
};

typedef struct F_PieceChunkList F_PieceChunkList;
struct F_PieceChunkList
{
  F_PieceChunkNode *first;
  F_PieceChunkNode *last;
  U64 node_count;
  U64 total_piece_count;
};

typedef struct F_PieceArray F_PieceArray;
struct F_PieceArray
{
  F_Piece *v;
  U64 count;
};

typedef struct F_Run F_Run;
struct F_Run
{
  F_PieceArray pieces;
  Vec2F32 dim;
  F32 ascent;
  F32 descent;
};

////////////////////////////////
//~ rjf: Font Path -> Handle * Metrics * Path Cache Types

typedef struct F_FontHashNode F_FontHashNode;
struct F_FontHashNode
{
  F_FontHashNode *hash_next;
  F_Tag tag;
  FP_Handle handle;
  FP_Metrics metrics;
  String8 path;
};

typedef struct F_FontHashSlot F_FontHashSlot;
struct F_FontHashSlot
{
  F_FontHashNode *first;
  F_FontHashNode *last;
};

////////////////////////////////
//~ rjf: Rasterization Cache Types

typedef struct F_RasterCacheInfo F_RasterCacheInfo;
struct F_RasterCacheInfo
{
  Rng2S16 subrect;
  Vec2S16 raster_dim;
  S16 atlas_num;
  F32 advance;
};

typedef struct F_Hash2InfoRasterCacheNode F_Hash2InfoRasterCacheNode;
struct F_Hash2InfoRasterCacheNode
{
  F_Hash2InfoRasterCacheNode *hash_next;
  F_Hash2InfoRasterCacheNode *hash_prev;
  U64 hash;
  F_RasterCacheInfo info;
};

typedef struct F_Hash2InfoRasterCacheSlot F_Hash2InfoRasterCacheSlot;
struct F_Hash2InfoRasterCacheSlot
{
  F_Hash2InfoRasterCacheNode *first;
  F_Hash2InfoRasterCacheNode *last;
};

typedef struct F_Hash2StyleRasterCacheNode F_Hash2StyleRasterCacheNode;
struct F_Hash2StyleRasterCacheNode
{
  F_Hash2StyleRasterCacheNode *hash_next;
  F_Hash2StyleRasterCacheNode *hash_prev;
  U64 style_hash;
  F32 ascent;
  F32 descent;
  F_RasterCacheInfo *utf8_class1_direct_map;
  U64 utf8_class1_direct_map_mask[4];
  U64 hash2info_slots_count;
  F_Hash2InfoRasterCacheSlot *hash2info_slots;
};

typedef struct F_Hash2StyleRasterCacheSlot F_Hash2StyleRasterCacheSlot;
struct F_Hash2StyleRasterCacheSlot
{
  F_Hash2StyleRasterCacheNode *first;
  F_Hash2StyleRasterCacheNode *last;
};

////////////////////////////////
//~ rjf: Atlas Types

typedef U32 F_AtlasRegionNodeFlags;
enum
{
  F_AtlasRegionNodeFlag_Taken = (1<<0),
};

typedef struct F_AtlasRegionNode F_AtlasRegionNode;
struct F_AtlasRegionNode
{
  F_AtlasRegionNode *parent;
  F_AtlasRegionNode *children[Corner_COUNT];
  Vec2S16 max_free_size[Corner_COUNT];
  F_AtlasRegionNodeFlags flags;
  U64 num_allocated_descendants;
};

typedef struct F_Atlas F_Atlas;
struct F_Atlas
{
  F_Atlas *next;
  F_Atlas *prev;
  R_Handle texture;
  Vec2S16 root_dim;
  F_AtlasRegionNode *root;
};

////////////////////////////////
//~ rjf: Metrics

typedef struct F_Metrics F_Metrics;
struct F_Metrics
{
  F32 ascent;
  F32 descent;
  F32 line_gap;
  F32 capital_height;
};

////////////////////////////////
//~ rjf: Main State Type

typedef struct F_State F_State;
struct F_State
{
  Arena *arena;
  
  // rjf: font table
  U64 font_hash_table_size;
  F_FontHashSlot *font_hash_table;
  
  // rjf: hash -> raster cache table
  U64 hash2style_slots_count;
  F_Hash2StyleRasterCacheSlot *hash2style_slots;
  
  // rjf: atlas list
  F_Atlas *first_atlas;
  F_Atlas *last_atlas;
};

////////////////////////////////
//~ rjf: Globals

global F_State *f_state = 0;

////////////////////////////////
//~ rjf: Basic Functions

internal F_Hash f_hash_from_string(String8 string);
internal U64 f_little_hash_from_string(String8 string);
internal Vec2S32 f_vertex_from_corner(Corner corner);

////////////////////////////////
//~ rjf: Font Tags

internal F_Tag f_tag_zero(void);
internal B32 f_tag_match(F_Tag a, F_Tag b);
internal FP_Handle f_handle_from_tag(F_Tag tag);
internal FP_Metrics f_fp_metrics_from_tag(F_Tag tag);
internal F_Tag f_tag_from_path(String8 path);
internal F_Tag f_tag_from_static_data_string(String8 *data_ptr);
internal String8 f_path_from_tag(F_Tag tag);

////////////////////////////////
//~ rjf: Atlas

internal Rng2S16 f_atlas_region_alloc(Arena *arena, F_Atlas *atlas, Vec2S16 needed_size);
internal void f_atlas_region_release(F_Atlas *atlas, Rng2S16 region);

////////////////////////////////
//~ rjf: Piece Type Functions

internal F_Piece *f_piece_chunk_list_push_new(Arena *arena, F_PieceChunkList *list, U64 cap);
internal void f_piece_chunk_list_push(Arena *arena, F_PieceChunkList *list, U64 cap, F_Piece *piece);
internal F_PieceArray f_piece_array_from_chunk_list(Arena *arena, F_PieceChunkList *list);
internal F_PieceArray f_piece_array_copy(Arena *arena, F_PieceArray *src);

////////////////////////////////
//~ rjf: Rasterization Cache

internal F_Hash2StyleRasterCacheNode *f_hash2style_from_tag_size(F_Tag tag, F32 size);
internal F_Run f_push_run_from_string(Arena *arena, F_Tag tag, F32 size, F_RunFlags flags, String8 string);
internal String8List f_wrapped_string_lines_from_font_size_string_max(Arena *arena, F_Tag font, F32 size, String8 string, F32 max);
internal Vec2F32 f_dim_from_tag_size_string(F_Tag tag, F32 size, String8 string);
internal Vec2F32 f_dim_from_tag_size_string_list(F_Tag tag, F32 size, String8List list);
internal U64 f_char_pos_from_tag_size_string_p(F_Tag tag, F32 size, String8 string, F32 p);

////////////////////////////////
//~ rjf: Metrics

internal F_Metrics f_metrics_from_tag_size(F_Tag tag, F32 size);
internal F32 f_line_height_from_metrics(F_Metrics *metrics);

////////////////////////////////
//~ rjf: Main Calls

internal void f_init(void);

#endif // FONT_CACHE_H