Replace the cosmic-text path with Parley layout and Swash rasterization, backed by shared glyph-atlas pages. Shaping, editing, rasterization, and glyph rendering move together because they share the text buffer and rendered-glyph types; splitting them further would require a temporary renderer that is immediately removed.
This is reconstructed rather than replayed from the extraction history. It also fixes issues found during review:
- texture binding changes remain set when an atlas patch follows a new page
- pressing an empty field places a caret and accepts input
- selection motion delegates collapse behavior to Parley
- character deletion follows logical clusters rather than visual neighbors
- the unused root-level Swash dependency is omitted
Four public-behavior integration tests live in `tests/text_edit.rs`: empty-field input, multibyte IME preedit replacement, UTF-8-safe backspace, and selection replacement. The old twelve-test inline block and implementation-restating cases are omitted.
Every added source comment was manually reviewed. Comments that narrated implementation or history were removed; retained comments document cache/rasterization keys, GPU upload constraints, focus representation, bidi geometry, or IME semantics.
Known limitation: atlas pages currently grow without eviction. Each page is 4 MiB on CPU and GPU. An arbitrary cap would leave cached rendered-text UVs pointing at reused glyph slots, so bounding this safely needs a later generation/invalidation change.
This changes public text types and signatures. GPU glyph rendering is covered by compilation rather than a live-surface test.
Verified with:
- `cargo fmt --all --check`
- `cargo clippy --workspace --all-targets -- -D warnings`
- `cargo test --workspace` (four integration tests pass)
Cargo still reports inherited future-incompatibility notices for existing wgpu/winit dependencies; there are no current clippy warnings.
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Co-authored-by: iris <2+iris@noreply.localhost>
Reviewed-on: iris/iris#10
Reviewed-by: iris <2+iris@noreply.localhost>
Co-authored-by: AIris <4+iris-ai@noreply.localhost>
iris-aiandiris