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Commits
| Author | SHA1 | Message | Date | |
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 admin
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af4009374d |
A browser app takes part in the desktop as a Wayland client does: fullscreen, the desktop's windows, activation and the shell protocol through forge/web, its own files through ltk::vfs, and images its caller names
On a page with forge/web an ltk app had a main surface, overlays and subsurfaces, but none of what a shell such as crustace needs from the compositor: fullscreen did nothing, the app heard nothing of the other windows, an activation token it asked for never came, forge/web was never told when a launched window had shown, the shell could not speak its protocol, and the app had no way to read its own files in a browser. Each now goes through the app's connection to forge/web, in the shape of the Wayland protocol it stands for. Fullscreen. On a page with forge/web, `App::fullscreen` and `App::start_fullscreen` send a `set_fullscreen` request for the main window, as `xdg_toplevel.set_fullscreen` does, instead of doing nothing; alone on a page the canvas still takes the browser's fullscreen. `examples/web_hello.rs` gains a button that toggles it. The desktop's windows. On connecting, the backend asks for the list of toplevels, and forge/web's `toplevel_opened` and `toplevel_closed` events become `ToplevelEvent`s for `App::on_toplevel_event`, as `ext-foreign-toplevel-list-v1` does on Wayland, so a shell's dock knows which applications have windows open. Activation. The tokens an app asks for with `App::take_activation_requests` are issued before it draws: forge/web's, through its `activation_token` request, or empty without a desktop, as on Wayland without xdg-activation, and handed to `App::on_activation_token` with their messages processed. A browser app that launched others through tokens waited for one that never came. Each surface's first presented frame is reported with a `presented` request (`WebSurfaceState::presented`), so forge/web knows when a window it launched has shown and can report it activated, which dismisses crustace's splash. The shell protocol. `platform/web/shell.rs` carries the JSON a shell speaks to forge over its socket over the app's connection to forge/web: `ltk::web::shell_send( json )` sends it as a `shell` request, and each `shell` event's message reaches the listener `ltk::web::set_shell_listener` gives, as JSON. What is sent before the app has connected is kept and sent once it has, so a shell can tell forge/web its theme while it starts. An overlay's role now carries its `App::overlay_namespace`, as its layer-shell namespace does on Wayland, so forge/web can tell a shell's overlays apart. The cursor over every surface. The CSS `cursor` was set on the main surface's element only, so over an overlay the pointer kept the page's arrow. `WebSurfaceState` keeps the element that takes its input, the shape moves to that of the surface the pointer enters, and `WebPlatform::cursor` keeps the last one asked for. An app's own files. `ltk::vfs`, through which ltk reads its themes, fonts and keyboard layouts, is public: `read`, `read_to_string`, `read_dir`, `is_file` and `is_dir` read the file system natively and, in a browser, the files the page loaded into memory. `ltk::web::load_tree( base, root ).await` loads any tree served with a `MANIFEST` under `root`, and `load_resources` is that into `/ltk` with the directory made the resource directory. `ltk::time::Instant` is public too, `std`'s natively and `web_time`'s on wasm32, where `std::time::Instant::now` panics, so an app that builds for both measures time with ltk's clock. wasm-bindgen-cli. `scripts/wasm-bindgen-cli.sh TOOLS_DIR` builds wasm-bindgen-cli into `TOOLS_DIR/bin` at the version of the `wasm-bindgen` crate ltk pins in its `Cargo.toml`, from its sources with a lock resolved for Debian's rustc, which is what `make web-deps` did inline and now runs. Since `make install` copies `scripts/` into the registry, a project that builds for the browser against the installed ltk, such as forge/web or crustace, gets the same CLI without a checkout of ltk. The README and docs/architecture.md say so. Images named by their caller. Every draw through `draw_image_data` fingerprints its pixels to find them in the image caches, which for a terminal means hashing every glyph of every frame. `Canvas::draw_image_keyed( key, rgba, w, h, dest, opacity )` is `draw_image_data` with `key` naming the pixels in place of their fingerprint: every draw with the same key must pass the same pixels, which are read only when the image is not cached. Both backends' caches are keyed by `ImageId`, `Content` for a fingerprint and `Keyed` for a caller's key, so a key never names an image drawn by content even when it equals its fingerprint. `GlesCanvas` and `SoftwareCanvas` gain `draw_image_keyed`, and their `draw_image_data` and it share one private `draw_image`. Tests check that a keyed image draws as its pixels do and that a key equal to a fingerprint is another image. A held button is not also tapped. A button with `on_long_press` and no `on_drag_start` stayed a tap after its hold fired, so releasing it sent its `on_press` as well. `GestureState::long_press_msg_fired` is set when the hold fires `long_press_msg` and suppresses the press message on release; a test covers it. `CHANGELOG.md` describes these changes. |
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admin
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20dc21448e |
A browser backend: ltk runs on a page's canvas through WebGL2, on a core that builds for wasm32, and a surface's scale may be fractional
ltk ran on Wayland and Android only. Running crustace and its apps in a browser needs, first, ltk apps running there; a window manager for the page is the next step. The runtime was already split from Wayland by the platform layer, so what kept it out of a browser was what the core and the runtime took from the operating system: calloop's epoll loop, EGL, a monotonic clock, a file system, threads and environment variables. The core builds for wasm32-unknown-unknown. `ltk::ChannelSender` is ltk's own type instead of a re-export of calloop's `Sender`, with the same `send` and `Clone`, so apps that only send and clone it build unchanged. The runtime arms its timers and channels through `event_loop/sources.rs` instead of a calloop `LoopHandle`: calloop's natively, and in a browser a queue the backend runs, which takes the due timers out, runs them on `AppData` and hands them back, and does not arm again one removed meanwhile. calloop, khronos-egl and raw-window-handle are dependencies off wasm32 only, where `egl_context.rs`, `UiSurface::try_new_gles` and `from_current_gles_loader` and the native GL names of `BorrowedGlesTexture` are left out; `sub_canvas` clones the uniform locations, which are `Copy` natively and only `Clone` on wasm. The monotonic clock is `crate::time::Instant`, `web_time`'s on wasm32, where `chrono` takes its `wasmbind` feature; the one subtraction that could go below the clock's origin, a surface's first `last_draw`, saturates. Themes, fonts, keyboard layouts and images are read through `vfs.rs`, the file system natively and on wasm32 files held in memory, so a wallpaper or an `Image::from_path` is now decoded from the file's bytes and its format told from its contents rather than its extension. The text-scale watcher, which runs gsettings on a thread, is left out on wasm32, and the built-in keyboard takes its language from `platform::language()`, `LANG` or the page's. criterion is a dev-dependency off wasm32 only, since rayon does not build there. The browser backend is the `web` feature, `platform/web/`, with wasm-bindgen, wasm-bindgen-futures, js-sys and web-sys. `build.rs` refuses it with another backend or for another target. A page's main thread must not block, so `ltk::run` sets the app up and returns, and the browser drives the loop: `AppData` lives in a closure a thread-local loop holds, which a `setTimeout` runs for messages, timers and page events and a `requestAnimationFrame` runs to draw. Event listeners and `ChannelSender::send` only queue and schedule, never touching `AppData`, so nothing they set off runs inside an iteration. The app draws on a canvas laid over the whole page, or the one `ltk::web::set_canvas` gives, through WebGL2 with the GLES canvas unchanged, its frame kept in its FBO, or without WebGL2 through `putImageData`. A lost context drops the GPU canvases and draws nothing until it is restored on a new `glow::Context`, so the glyph atlas and the caches of the old one are not reused. The main surface's logical size is the canvas's CSS size; the window's `resize` refits it, and on ltk's own canvas a hidden element padded by `env( safe-area-inset-* )` gives the insets. Input comes from Pointer Events, a mouse as the pointer and fingers and pens as touches, the wheel, in detents when it scrolls lines, and keys, whose keysym comes from `KeyboardEvent.key` and code from `.code` as the Linux input code Wayland reports; keys repeat on the browser's clock, AltGr types its character, and on macOS Command is Ctrl. ltk takes every key the browser lets a page have, and while fullscreen those `navigator.keyboard.lock()` adds in Chromium. Copies go to `navigator.clipboard.writeText`; a page reads the clipboard only from a `paste` event, so Ctrl+V is let through to the browser and held until its `paste` has put the text in `AppData::clipboard`, and a paste from the browser's menu comes with a Ctrl+V of its own. The cursor's shape is the canvas's CSS `cursor`. The built-in keyboard serves text where the page is used by touch. Panics go to the browser's console. When the app exits, the listeners are removed, the canvas receives an `ltk-exit` event and the app is dropped. The new `RunError::NoDocument` is returned where there is no page, as in a worker. Resources are the tree an Android package carries. `scripts/web-assets.sh` builds it through `android-assets.sh`, and `ltk::web::load_resources( base ).await` fetches its `MANIFEST` and every file it lists, with the manifest's hash in their URLs so a changed tree is not served from the browser's cache, into memory under `/ltk`, which becomes the resource directory. The per-script fallback fonts are read through `resources::read_font`, so a path that does not exist is found by file name in the resource directory's `fonts/`, where a page bundles them. A surface's scale may be fractional. `SurfaceState::scale_factor` is an `f32`, which `Platform::prepare_canvas`, `Presentation::scale` and the paint path take as it is; a surface's physical size is its logical size times the scale, rounded once, and `buffer_scale()` gives the whole number Wayland's buffer scale and regions need. Wayland and Android still set whole scales, so nothing changes there; the browser backend sets the page's `devicePixelRatio`, so the canvas holds the display's own pixels at any zoom. `App::on_scale_changed` keeps its `u32`, the scale rounded, and `App::on_resize` gives the exact physical size. The fallback-theme banner placed its text as if `draw_text` took the top of the line rather than its baseline, so most of the text fell above the banner, out of the surface; it is now centred as the title bar's is. Building. `make web-check` typechecks the backend. `make web-deps` installs Debian's std for wasm32 and wasm-bindgen-cli, whose version must be the one of the wasm-bindgen crate in `Cargo.lock`: the crate is pinned to 0.2.117, the last whose CLI builds with Debian's rustc 1.85, and since the lock the CLI was published with needs a newer rustc and `cargo install` ignores rust-version when it resolves, the CLI is built from its sources with a lock resolved for the rust-version it declares, into `target/tools`, where the Makefile finds it. `make web-assets` builds the resources with the in-tree default theme and the fallback fonts `WEB_FONTS` names. `examples/web_hello.rs`, a counter and a text field, and `web/index.html` are the smoke test: `make web-example` builds them into `target/web/` and `make web-serve` serves them. `make install` now copies `web/` into the registry. `README.md`, `docs/architecture.md` and `CHANGELOG.md` describe the backend, and `docs/cookbook.md` points to `ChannelSender`'s new home. Not done. In a browser there are no overlays, secondary surfaces or subsurfaces, no dead keys or input methods, no accessibility tree and no primary selection, and a canvas that changes size while the window does not is not refitted. Pasting relies on the browser sending `paste` to a focused canvas, which Chrome and Firefox do. The page fetches its whole resource tree, about 7 MB, before the app starts. There are no tests for the browser backend, `Sources`' queue or `vfs.rs`'s in-memory files, and fractional scales may leave one-pixel artefacts where edges fall between pixels. |