Files
libakgl/include/akgl/sprite.h
Andrew Kesterson 3a262bee54 Give every exported function a declaration, and check that it stays that way
Closes internal-consistency items 7 through 15. Nineteen non-static functions
were in the ABI with no declaration anywhere, so no consumer could call them
and any consumer could collide with them.

The four gamepad_handle_* functions are the ones that mattered: controller.h
declared akgl_controller_handle_button_down and three siblings that did not
exist, so anything compiled against the header alone failed to link. The
definitions carry the declared names now, which also closes Defects -> Known
and still open item 10, and their documentation moved to the header.

The rest are either declared under a "part of the internal API" block --
akgl_game_save_actors and akgl_game_load_versioncmp, which tests/game.c had to
declare for itself, plus six tilemap loader helpers the untested-loader work
wants to reach -- or static, which is what the four save iterators and
load_objectnamemap should always have been. akgl_path_relative_from is deleted:
declared nowhere, called from nowhere, never wrote its output, and leaked a
pooled string on every call, so it closes Known and still open item 4 and item
40 by ceasing to exist.

scripts/check_api_surface.sh keeps it closed. It reads the built library's
dynamic symbol table and every public header with comments stripped, and fails
on an exported akgl_* symbol that is declared nowhere. Stripping comments is
the whole point -- four of these were mentioned in controller.h prose, which is
how they went unnoticed.

The pool-size ceilings are defined once, in heap.h, so the #ifndef override
hook fires for the first time; actor.h, sprite.h and character.h were defining
the same four unconditionally from headers heap.h includes above its own guard.
tests/header_pool_override.c fails the compile if that regresses.

Also here: (void) rather than () on the twelve no-argument entry points,
AKERR_NOIGNORE only on declarations, static helpers with the akgl_ prefix
dropped, and the six parameter-name mismatches. akgl_get_json_with_default had
its two contexts swapped rather than merely misspelled -- the incoming one was
`err` and its own was `e`, which is the name reserved for an incoming one.

24/24 pass, reindent --check clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-01 07:33:35 -04:00

170 lines
10 KiB
C

/**
* @file sprite.h
* @brief Spritesheets (one texture, many frames) and the animations cut out of them.
*
* The split is deliberate: an akgl_SpriteSheet owns the `SDL_Texture` and the
* frame grid, and any number of akgl_Sprite animations point at the same sheet
* and name the frame indices they use. Loading two sprites from the same image
* loads the image once -- akgl_sprite_load_json looks the sheet up in
* #AKGL_REGISTRY_SPRITESHEET by resolved path before creating one.
*
* Both are pool objects (akgl_heap_next_sprite, akgl_heap_next_spritesheet) and
* both publish themselves in a registry under their name, which is how
* akgl_character_sprite_add and the tilemap loader find them. Because loading a
* sheet uploads a texture, the renderer has to exist first -- so
* akgl_render_2d_init, or akgl_game_init, before any of this.
*/
#ifndef _AKGL_SPRITE_H_
#define _AKGL_SPRITE_H_
#include <SDL3/SDL_properties.h>
#include <SDL3/SDL.h>
#include <akerror.h>
#define AKGL_SPRITE_MAX_FRAMES 16
#define AKGL_SPRITE_MAX_NAME_LENGTH 128
#define AKGL_SPRITE_MAX_REGISTRY_SIZE 1024
#define AKGL_SPRITE_SHEET_MAX_FILENAME_LENGTH 512
/** @brief Stores a loaded spritesheet texture and frame geometry. */
typedef struct {
uint8_t refcount; /**< Pool bookkeeping; 0 means the slot is free. Destroys the texture when it reaches 0. */
SDL_Texture *texture; /**< The whole sheet as one GPU texture. Owned by this struct. */
char name[AKGL_SPRITE_SHEET_MAX_FILENAME_LENGTH]; /**< Registry key: the resolved path the image was loaded from. */
uint16_t sprite_w; /**< Frame width. Vestigial: nothing in the library writes or reads it; the grid comes from akgl_Sprite::width. */
uint16_t sprite_h; /**< Frame height. Vestigial, same as sprite_w. */
} akgl_SpriteSheet;
/** @brief Describes an animated sprite and its spritesheet reference. */
typedef struct {
uint8_t refcount; /**< Pool bookkeeping; 0 means the slot is free. One reference per character that maps it. */
uint8_t frameids[AKGL_SPRITE_MAX_FRAMES]; /**< Frame numbers on the sheet, in playback order. Counted left to right, then wrapping to the next row. */
uint32_t frames; /**< How many entries of frameids are in use. */
uint32_t width; /**< Frame width in pixels; also the horizontal stride used to find a frame on the sheet. */
uint32_t height; /**< Frame height in pixels; the vertical stride once frames wrap to the next row. */
uint32_t speed; /**< Nanoseconds one frame is held. Read from JSON in milliseconds and scaled by #AKGL_TIME_ONEMS_NS. */
bool loop; /**< Restart from frame 0 when the last frame is reached, instead of holding it. */
bool loopReverse; /**< Play back down to frame 0 instead of jumping to it -- a ping-pong loop. */
char name[AKGL_SPRITE_MAX_NAME_LENGTH]; /**< Registry key, from the JSON `name` field. */
akgl_SpriteSheet *sheet; /**< The sheet these frames are cut from. Borrowed, not owned. */
} akgl_Sprite;
// initializes a new sprite to use the given sheet and otherwise sets to zero
/**
* @brief Zero a pooled sprite, bind it to a sheet, and publish it in the sprite registry.
*
* Sets the name and the sheet and takes the first reference; everything else --
* frame list, geometry, speed, loop flags -- is left at zero for the caller, or
* akgl_sprite_load_json, to fill in. The sheet is borrowed, so this does *not*
* take a reference on it: releasing the sheet out from under a live sprite
* leaves a dangling pointer.
*
* @param spr Pooled sprite to initialize, normally from akgl_heap_next_sprite.
* Required. Any previous contents are discarded.
* @param name Registry key, NUL-terminated. Required. Copied at a fixed
* #AKGL_SPRITE_MAX_NAME_LENGTH bytes, so a shorter string reads
* past its end -- pass a name from an akgl_String or another
* buffer of at least that size. An existing entry with the same
* name is silently replaced.
* @param sheet The spritesheet this sprite's frames come from. Required.
* @return `NULL` on success, otherwise an error context owned by the caller.
* @throws AKERR_NULLPOINTER If @p spr, @p name, or @p sheet is `NULL`.
* @throws AKERR_KEY If the sprite cannot be written into #AKGL_REGISTRY_SPRITE
* -- in practice, because akgl_registry_init has not run.
*/
akerr_ErrorContext AKERR_NOIGNORE *akgl_sprite_initialize(akgl_Sprite *spr, char *name, akgl_SpriteSheet *sheet);
// loads a given image file into a new spritesheet
/**
* @brief Load an image file as a texture and publish it as a spritesheet.
*
* Uploads @p filename through SDL_image using the global `akgl_renderer`, so the
* renderer must already be initialized. The sheet is registered in
* #AKGL_REGISTRY_SPRITESHEET under @p filename, which is the key
* akgl_sprite_load_json looks it up by to avoid loading the same image twice.
*
* @param sheet Pooled spritesheet to initialize, normally from
* akgl_heap_next_spritesheet. Required. Zeroed first, so a
* texture it already held is leaked rather than destroyed.
* @param sprite_w Frame width in pixels. Accepted and currently discarded --
* the frame grid actually used at draw time comes from the
* akgl_Sprite's `width`/`height`, not from here.
* @param sprite_h Frame height in pixels. Same caveat as @p sprite_w.
* @param filename Path to the image, in any format SDL_image can decode.
* Required. Doubles as the registry key, so callers should pass
* an already-resolved path; two spellings of the same file are
* two sheets. Truncated at
* #AKGL_SPRITE_SHEET_MAX_FILENAME_LENGTH.
* @return `NULL` on success, otherwise an error context owned by the caller.
* @throws AKERR_NULLPOINTER If @p sheet or @p filename is `NULL`.
* @throws AKGL_ERR_SDL If the image cannot be loaded -- missing, unreadable, or
* a format SDL_image was not built with. The message carries
* `SDL_GetError()`.
* @throws AKERR_KEY If the sheet cannot be written into
* #AKGL_REGISTRY_SPRITESHEET.
*/
akerr_ErrorContext AKERR_NOIGNORE *akgl_spritesheet_initialize(akgl_SpriteSheet *sheet, int sprite_w, int sprite_h, char *filename);
/**
* @brief Build a sprite -- and, if needed, its spritesheet -- from a JSON definition file.
*
* Reads `name`, `width`, `height`, `speed` (seconds, scaled to milliseconds),
* `loop`, `loopReverse`, a `frames` array of frame indices, and a `spritesheet`
* object holding `filename`, `frame_width`, and `frame_height`. The sheet's
* `filename` is resolved *relative to the directory of @p filename*, so a sprite
* definition can sit next to its image and move with it.
*
* If a spritesheet with that resolved path is already registered it is reused;
* otherwise one is claimed from the pool and loaded. On failure both the sprite
* and any sheet loaded for it are released again.
*
* @param filename Path to the JSON document. Required. Must be shorter than
* #AKGL_MAX_STRING_LENGTH -- it is copied into a pooled string
* so `dirname` can be taken without modifying the caller's
* buffer.
* @return `NULL` on success, otherwise an error context owned by the caller.
* @throws AKERR_NULLPOINTER If @p filename is `NULL`, or if the file cannot be
* opened or does not parse. The message carries jansson's line number
* and text.
* @throws AKERR_OUTOFBOUNDS If @p filename is at least #AKGL_MAX_STRING_LENGTH
* bytes long, or if the `frames` array is indexed past its end.
* @throws AKERR_KEY If a required key is absent, or if the sprite or sheet
* cannot be added to its registry. The message names the key.
* @throws AKERR_TYPE If a key is present with the wrong JSON type -- `speed` as
* a string, `frames` as an object.
* @throws AKGL_ERR_SDL If the spritesheet image fails to load.
* @throws AKGL_ERR_HEAP If the sprite, spritesheet, or string pool is exhausted.
*
* @note The `frames` array is not bounded against #AKGL_SPRITE_MAX_FRAMES. A
* definition with more than 16 frames writes past `frameids` into the
* rest of the struct.
*/
akerr_ErrorContext AKERR_NOIGNORE *akgl_sprite_load_json(char *filename);
/**
* @brief Work out where one animation frame sits on its spritesheet.
*
* Frames are numbered in reading order across the sheet: multiply the frame
* number by the sprite width, then wrap whole rows off the right-hand edge of
* the texture and step down by the sprite height for each. Callers use the
* result as the source rectangle for `SDL_RenderTexture`.
*
* @param self The sprite whose sheet and frame geometry to use. Required,
* along with its `sheet`.
* @param srccoords Receives the frame's rectangle on the sheet, in pixels.
* Required -- the return value is the error context.
* @param frameid Index into the sprite's `frameids` array, not a frame number
* on the sheet. Not bounds-checked against `frames` or
* #AKGL_SPRITE_MAX_FRAMES; an out-of-range index reads a
* neighbouring struct member and yields a nonsense rectangle
* rather than an error.
* @return `NULL` on success, otherwise an error context owned by the caller.
* @throws AKERR_NULLPOINTER If @p self, @p srccoords, or `self->sheet` is
* `NULL`. Note that `sheet->texture` is dereferenced without a check,
* so a registered-but-unloaded sheet is a crash rather than an error.
*/
akerr_ErrorContext *akgl_spritesheet_coords_for_frame(akgl_Sprite *self, SDL_FRect *srccoords, uint8_t frameid);
#endif //_AKGL_SPRITE_H_