The UI subsystem now draws. akgl_ui_frame_begin/frame_end bracket one frame's
CLAY() declarations: begin clears the error stash and starts the clay layout,
end computes it and walks the render commands through a backend -- RECTANGLE
as (rounded) fills, BORDER as radius-shortened edge fills plus corner arcs,
TEXT through akgl_text_rendertextat one wrapped line per command, IMAGE as an
akgl_Sprite's first frame stretched to the bounding box, and the SCISSOR pair
through akgl_draw_set_clip, cleared again on any exit so a failed frame
cannot leave the world clipped.
akgl_ui_font_register maps registry font names onto clay's uint16_t fontIds.
The table keeps the *name* and resolves it per use -- fonts are not reference
counted, and a cached TTF_Font* would dangle where a name reports "gone"
honestly. Clay_TextElementConfig.fontSize is deliberately ignored: libakgl
bakes the size into the handle at load, so one face at two sizes is two ids.
The measure bridge passes clay's non-NUL-terminated slices straight to
SDL_ttf's explicit-length TTF_GetStringSize -- no copy, no scratch. Its
signature has no error channel, so failures report zero-by-zero and stash a
message that frame_end raises, the same route clay's own void error handler
uses; layout errors take precedence over drawing and one bad frame leaves the
next one clean.
Tests drive real CLAY() layouts through the software renderer and read pixels
back: fill placement, border edges with an empty middle, a child clipped by
its container, text landing in its colour, slice-vs-whole measurement
agreement, fontId table dedupe/refusal/exhaustion, and the bracket's
begin/begin, end-without-begin and failure-recovery contracts.
Co-Authored-By: Claude Code (Claude Fable 5, claude-fable-5) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
clay v0.14 (deps/clay, zlib licence) supplies the layout engine for the new
akgl_ui subsystem. Sources-listed rather than add_subdirectory()'d, on the
semver/libccd precedent: clay's CMakeLists declares no library target, builds
its examples by default, and requires CMake 3.27 against this project's 3.10.
src/ui_clay.c is the one CLAY_IMPLEMENTATION translation unit, compiled -w on
the vendored-code terms but with clay's symbols deliberately exported --
consumers' CLAY() macros resolve against libakgl.so, and akgl/ui.h warns them
never to link a second clay.
The subsystem is runtime-optional the way collision is: always compiled in,
inert until akgl_ui_init(), which bounds clay to the overridable AKGL_UI_*
ceilings, checks Clay_MinMemorySize() against a static BSS arena (no malloc),
and refuses with both numbers in the message when it does not fit. Measured:
812544 bytes at the default 1024 elements / 4096 measured words, against a
1 MiB arena. clay's void-callback layout errors are logged as they happen and
the first is stashed for the error protocol to raise later.
AKGL_ERR_UI joins the status band before AKGL_ERR_LIMIT, named in
akgl_error_init. New `ui` test suite covers validation, the init/shutdown
lifecycle, and arena exhaustion via the akgl_ui_arena_limit test hook (same
contract as akgl_ccd_arena_set_limit). clay.h is installed beside semver.h,
its licence beside libccd's, and the headers suite proves akgl/ui.h
self-contained -- clay.h compiles clean under -Wall.
Co-Authored-By: Claude Code (Claude Fable 5, claude-fable-5) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
