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event_loop, a11y, text_shaping: AccessKit AT-SPI2 bridge, cross-app clipboard, xdg-activation, HarfBuzz shaping, multi-touch hooks
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Five orthogonal capabilities land together because they share the same `try_run` plumbing: an optional global is bound at startup, a piece of state is added to `AppData`, the run-loop iteration drains an inbox / pushes a frame snapshot, and the public surface gains a small set of opt-in `App` hooks. Nothing here breaks an existing app — every new path degrades to a no-op when the compositor does not advertise the relevant global or when the platform adapter cannot start.
AT-SPI2 accessibility via AccessKit. A new `src/a11y/` module owns the platform adapter and the inbound `ActionRequest` channel. `A11yState::try_new` constructs an `accesskit_unix::Adapter`; when the AT-SPI2 daemon is not on the session bus (headless CI, locked-down compositors) the constructor returns `None` and the rest of the pipeline runs unchanged. After every successful `draw_frame`, the run loop builds a fresh `accesskit::TreeUpdate` from `widget_rects` and pushes it through the adapter — main surface plus every visible overlay, each translated to global coordinates via `surface_offset_for` so screen readers report positions in the same frame the user sees. Buttons / toggles / checkboxes / radios / list items / sliders / text edits map to the matching `Role`s; `Click` and `Focus` actions are advertised on every interactive node; inbound action requests are drained at the top of each iteration and translated into a synthetic press / focus on the matching widget. The integration is documented as best-effort in `docs/architecture.md` under "Known gaps and non-goals": hierarchical nesting, per-widget accessible names, live regions and `Action::SetValue` are listed as the natural follow-ups that the foundation now supports but does not yet wire.
Cross-application clipboard via `wl_data_device_manager`. A new `src/event_loop/data_device.rs` bridges the existing process-local `clipboard: String` to the Wayland selection. Outbound (Ctrl+C / Cut): after the local clipboard is populated, `publish_clipboard_selection` creates a `CopyPasteSource` offering `text/plain;charset=utf-8` and installs it as the seat's selection; `DataSourceHandler::send` writes the cached string into the fd the peer hands us. Inbound (Ctrl+V from another app): `DataDeviceHandler::selection` asks for the offered text via `WlDataOffer::receive`, spawns a tiny worker thread to drain the read pipe with a 16 MiB cap to prevent paste-bomb DoS, and posts the result back through an `mpsc::Sender` that the run loop drains each iteration into `data.clipboard`. The `clipboard:` field's doc-comment is updated to reflect the new behaviour: process-local when the compositor does not advertise the global, synchronised with the seat selection otherwise.
External drag-and-drop reception. The same `data_device` module handles `DragOffer` enter / motion / leave / drop_performed: `on_drop_motion( x, y )` fires while the drag hovers over the surface, `on_drop_leave()` when it withdraws without dropping, and `on_drop_received( x, y, mime, text )` when an external payload (`text/uri-list`, `text/plain`, …) is released on top of an ltk window. The receive path reuses the same worker-thread / channel pattern as the clipboard so the run loop never blocks on the read fd. Three new `App` hooks expose the events with no-op defaults; apps that ignore them get the previous behaviour.
`xdg-activation-v1`. The global is bound optionally; when it is present, `try_run` reads `$XDG_ACTIVATION_TOKEN` from the environment, removes it immediately (single-use; preventing leaks into child processes) and stashes it on `AppData::activation_token_pending`. After the first successful configure of the main surface — the earliest point at which `xdg_activation_v1.activate` is meaningful — the token is consumed once and the surface raised to focus. Compositors without the global leave `activation_state` as `None` and the inbound path silently degrades. An `App::request_activation_token` outbound path is reserved on the trait but not yet exercised here.
HarfBuzz shaping. A new `src/text_shaping.rs::shape_line` drives both renderers: the logical-order string is run through `unicode-bidi`, split into per-font sub-runs, and shaped through `rustybuzz`. Each `PositionedGlyph` carries the per-font `glyph_id`, the visual advance and the ink offsets — exactly what `fontdue::Font::rasterize_indexed` needs to render Arabic connected forms, Devanagari clusters and CJK shaped glyphs correctly. The GLES atlas is re-keyed on `(glyph_id, size_bits, font_id)` so glyphs from different fonts at the same size no longer collide, and the atlas format is selected per ES profile (`GL_R8` / `GL_RED` on ES3, `GL_LUMINANCE` on ES2) — the fragment shader samples `.r` for both, since `GL_LUMINANCE` replicates the coverage byte into `.r=.g=.b`. Software path follows the same key. New `Cargo.toml` deps: `unicode-bidi = "0.3"`, `rustybuzz = "0.14"`.
Multi-touch hooks. `App::on_touch_down / on_touch_move / on_touch_up( id, x, y )` expose the raw `wl_touch.id` of every secondary finger. The first finger to land remains the *primary slot* and is fed through the regular gesture machine (`on_pointer_*`, swipe, scroll, long-press, drag-and-drop). Every additional finger fires the new callbacks instead, leaving the existing single-slot behaviour untouched for apps that do not override them. This is the substrate for app-defined pinch-zoom / two-finger pan; the toolkit itself does not yet ship a built-in pinch gesture (called out in the same "Known gaps" doc section).
`event_loop::frame` extracted from `draw/mod.rs`. The `draw_frame` orchestrator and its per-format SHM helper (`pick_shm_format`) move into `src/event_loop/frame.rs`, leaving `draw/` strictly responsible for per-surface paint primitives. The import in `event_loop/run.rs` is rewritten accordingly; `draw/mod.rs` shrinks from 192-line orchestrator to a thin module index.
Overlay teardown safety. `AppData::discard_overlay( id )` synchronously removes a destroyed overlay from the map and rewrites every per-device focus that pointed at it (pointer, keyboard, every touch slot), migrating an in-flight long-press drag to the main surface the same way `reconcile_overlays` does. Used by the compositor-driven destruction paths (`PopupHandler::done`, `LayerShellHandler::closed`) where waiting for the next reconcile would leave a window in which `surface()` / `surface_mut()` panic. The non-panicking siblings `try_surface` / `try_surface_mut` are added for callers on async dispatch paths (IME `Done`, tooltip arm) that may race a teardown.
Miscellaneous. CI: `master` → `main` to match the actual default branch. `Makefile` adds `cargo run --example dialog` to the examples target. `src/lib.rs` re-exports `widget::scroll::ScrollAxis` so apps can configure a `scroll()` axis without reaching into a `pub(crate)` module. `Cargo.toml` adds `accesskit = "0.17"` and `accesskit_unix = "0.13"`. `docs/architecture.md` gains the "Known gaps and non-goals" section that enumerates the new capabilities, what still ships flat, and what is deferred (per-widget a11y labels, primary selection, intra-process multi-touch gestures, `wp_fractional_scale_v1`).
This commit is contained in:
Pedro M. de Echanove Pasquin
2026-05-16 22:09:59 +02:00
parent 4aa3480b64
commit 4a80165428
48 changed files with 3088 additions and 645 deletions
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docs/architecture.md
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@@ -245,3 +245,28 @@ When a redraw feels sluggish: add a one-line print at the top of `view()` and co
| Theme on disk (slot-typed JSON) | `ltk/themes/default/theme.json`, `ltk::ThemeDocument::find` |
For a self-contained example that exercises overlays, theme switching, and animation in one ~300-line file, see `examples/mini_shell.rs`.
## Known gaps and non-goals
A short, honest list of what ltk does not currently provide. None of these are accidental — each is either deferred work or a deliberate non-goal. The list is here so that downstream consumers and audit reviewers know what to plan around without reading the source.
**AT-SPI2 / assistive technology bridge — wired through AccessKit, with composite widgets still flat.** Combo, Notebook tabs, DatePicker and TimePicker render as collections of inner widgets and currently expose those leaves individually (a combo trigger reads as "Button" + its caption, the popup items as `ListItem`s inside an overlay). Promoting them to their semantic roles (`ComboBoxMenuButton` with `Expanded` state, `TabList`/`Tab`/`TabPanel`, `Date`) needs each compound widget to declare an "outer rol hint" the layout pass can attach to the `LaidOutWidget` it pushes. Tracked separately.
ltk delegates the AT-SPI2 D-Bus protocol to [`accesskit_unix`]. After every layout pass, the runtime hands the platform adapter a fresh [`accesskit::TreeUpdate`] built from `widget_rects` (one accessible node per laid-out widget, plus a `Window` root). Buttons / toggles / checkboxes / radios / list items map to `Role::Button` / `Role::Switch` / `Role::CheckBox` / `Role::RadioButton` / `Role::ListItem`; sliders to `Role::Slider`; single- and multi-line text edits to `Role::TextInput` / `Role::MultilineTextInput`. Each interactive node advertises the `Click` and `Focus` actions, and inbound action requests (Orca pressing a button, switch-control moving focus) are translated into a synthetic press / focus on the matching widget the next iteration of the run loop.
The integration is best-effort: when the AT-SPI2 daemon is not on the session bus (headless CI runners, locked-down compositors) the adapter creation returns `None` and the rest of the pipeline runs unchanged. The current cut covers the common cases — buttons, lists, form fields, dialogs — and intentionally leaves room for follow-up:
- **Hierarchical nodes (groups, lists with explicit children)**: today the tree is flat. AccessKit supports nesting but the layout pass does not expose `Column` / `Row` / `Container` parents to the accessibility builder. Adding that requires either recording the nesting on `LaidOutWidget` or walking `Element` again from the a11y side.
- **Per-widget accessible label / description / `LabelledBy` relations**: the API to set them (`Button::accessible_name(...)`, etc.) is not exposed yet — labels currently fall back to the widget's tooltip text. Adding the builders is mechanical but touches every widget module.
- **Live regions**: status messages, notifications and OSDs that should announce themselves on appearance need `Live::{Polite, Assertive}` on the relevant nodes. Not wired in.
- **`Action::SetValue` for sliders and text inputs**: the inbound action handler does not yet translate these requests into the corresponding widget message. Adding them needs the same plumbing as `Click` / `Focus` but with payload extraction from `ActionData`.
Downstream consumers shipping into regulated environments (EN 301 549, WCAG 2.1 AA, EAA) should still treat the integration as a starting point that needs a real audit with assistive technology users — the foundation is in place but the per-widget metadata work is what determines whether Orca actually reads a useful announcement.
**Cross-application drag-and-drop — deferred.** The clipboard now bridges to the Wayland selection via `wl_data_device_manager` (see `event_loop/data_device.rs`), so Ctrl+C / Ctrl+V crosses application boundaries when the compositor advertises the global. Middle-click primary selection (`zwp_primary_selection_v1`) and inter-app drag-and-drop targets (drop-zone widgets that accept text / URI lists from outside the process) are still pending — they share most of the offer / source plumbing but need widget-level drop-target wiring on top.
**Multi-touch — deferred.** `input/touch/mod.rs` is single-slot by design today; a second finger overwrites the first. Pinch-zoom, two-finger scroll and gesture combos are out until the slot table lands. Tracked separately.
**HarfBuzz shaping — wired in.** `src/text_shaping.rs::shape_line` now drives both renderers: the line is BiDi-reordered, split into per-font sub-runs and shaped through rustybuzz. The glyph cache is keyed on `(glyph_id, size_bits, font_id)` and each glyph is rasterised by index via `fontdue::Font::rasterize_indexed`, so Arabic connected forms, Devanagari clusters and CJK shaped glyphs render correctly.
**xdg-activation-v1 and fractional scale — deferred.** Activation tokens (so an external launcher can raise an ltk window with focus) and `wp_fractional_scale_v1` (so 125 % / 150 % outputs render natively instead of via compositor downscale) are tracked as upcoming protocol work.