# iris: notable public API changes For Iris to read on her own time. Each entry is a change to iris's public surface that a widget author or app author would notice: a trait method added, removed or re-shaped; a type that callers construct differently; a capability that moved. Small and trivial changes do not go here. An entry gives the date, what changed, why, and a short before/after where it helps judge the change without the session that made it. Newest first. ## 2026-09-05: `List`, a virtualised bottom-anchored list (RUST.md's I3) A new widget, `iris::widget::List` (`iris/src/widget/list.rs` -- read its module doc first), for the transcript's kind of screen: variable-height rows, keyed by a `u64`, composed only while visible, moved rather than re-laid-out on scroll, a scroll anchor that survives a row inserted above it, "more" sentinels at each end, and "hold the edge nearest the tap" when a row's height changes (`note_tap`, resolved in the layout pass). ```rust let mut list = List::new(Axis::Y); list.push_back(ListRow::new(key, row_widget)); // O(1) list.push_front(ListRow::new(older_key, row)); // O(1), anchor unaffected list.set_more_before(Some(spinner_widget)); // sentinel, drawn at the edge list.note_tap(viewport_y); // before mutating a row's height let (top, bottom) = list.extent(key).unwrap(); // last frame's on-screen box, if visible ``` Built entirely out of existing primitives (`Painter::widget`/`widget_within`/ `reposition`/`draw_twice`, and `draw_inner`'s own old-children diffing) -- no new mechanism was added to the render core for it. One correctness lesson worth reading even for other widgets: a row that fills whatever region it is offered (`Rect`, `is_size_independent`) cannot be measured at a throwaway oversized region and then merely `reposition`ed into place -- `reposition` only ever writes an offset, never a size, so the oversized primitive stays oversized. `List` fixes this by caching each row's real height once measured and placing an already-known row directly at its exact box; see `list.rs`'s `place` for the full reasoning and `a_fill_shaped_background_is_not_left_oversized` for the regression test. ## 2026-09-05: a second backend (android-view), and what moved to make room for it RUST.md's I2. Three changes a widget or app author would notice, all in service of the same thing: `default` (winit) and the new `android` (android-view) backends sharing what does not depend on windowing. - **`Selector`/`Selectable`'s bound changed from `Rsc::State: HasDefaultUiState` to `Rsc::State: FocusHost`** (new trait, `attr.rs`). `HasDefaultUiState` still exists and still works — `default/attr.rs` now implements `FocusHost` for anything that has it — so a winit app's existing code is unaffected. An Android app implements `FocusHost` via `HasAndroidUiState` instead. Affects only an app that referenced `HasDefaultUiState` directly at a `Selectable`/`Selector` call site rather than through `.attr::(())`, which nothing in-tree does. - **`Tasks::init` takes `Arc` instead of `Arc`.** `RequestRedraw` (`task.rs`) is one method, `fn request_redraw(&self)`; `winit::window::Window` implements it (`default/render.rs`), so `Tasks::init(window)` at a call site is unchanged by inference. Only matters if something constructed a `Tasks` directly rather than through `DefaultRsc`/`AndroidRsc`. - **`TextEdit::apply_event`/`TextInputResult` are `#[cfg(not(target_os = "android"))]`** — they take a `winit::event::KeyEvent`, which does not exist on Android; `android/input.rs` drives the same primitives (`backspace`/`delete`/`motion`/`insert`, all still unconditional) from `ndk::event::Keycode` directly instead. New unconditional getters on the way: `TextEdit::text()`/`selection_range()`/`caret()`, and `TextEditCtx::delete_byte_range`/`set_cursor_byte` — the primitives `android/ime.rs`'s `InputConnection` bridge needed and that were not previously exposed publicly. ## 2026-09-04: `Widget::draw` reports the size it used; `desired_width`/`desired_height` are gone A widget used to implement three methods (`draw`, `desired_width`, `desired_height`); it now implements one, `fn draw(&mut self, painter: &mut Painter) -> Size`, which draws into `painter.region()` and returns how much of it was used. Why: the two extra methods routinely re-simulated what `draw` was about to do anyway (`Span::desired_ortho` copied its own draw loop to get cross-axis sizing right) — one visit per widget per frame instead of up to three. A container that needs a child's size before placing it (alignment, centering) draws the child once at a provisional region, reads the returned `Size`, and calls the new `Painter::reposition` to move it into its final spot — an O(1) offset write, not a second draw. A widget whose drawn output never depends on the size it's given (a fixed-size `Rect`, a decoded `Image`) overrides the new `fn is_size_independent(&self) -> bool { false }` to `true`, which skips redrawing it when only its offered region changes shape. ```rust // before fn draw(&mut self, painter: &mut Painter) { /* ... */ } fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len { /* ... */ } fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len { /* ... */ } // after fn draw(&mut self, painter: &mut Painter) -> Size { /* ... */ } ``` `SizeCtx` and `Cache` are gone with it — see `LAYOUT.md` for the full design, the move-offset mechanism this shipped alongside, and the file list. ## 2026-09-04: texture pipeline rebuilt off the binding array `Textures`/`TextureHandle`, `GlyphPrimitive`, and `UiRenderNode::new` all changed shape. Why: the old pipeline bound every texture ever drawn in one `binding_array>` and asked every device, unconditionally, for `VK_EXT_descriptor_indexing` — a real share of Android GPUs lack it, and it failed outright on the Android emulator's software Vulkan. See TEXTURES.md's "Recommended shape" and "Implemented, 2026-09-04". - **`UiRenderNode::new` drops its `limits: UiLimits` parameter, and `UiLimits` is gone.** Before: `UiRenderNode::new(&device, &queue, &config, UiLimits::default())`. After: `UiRenderNode::new(&device, &queue, &config)`. Nothing replaces it — there are no more binding-array limits to size. - **`src/default/render.rs`'s device request asks for no features and no binding-array limits.** Before: `required_features: Features::TEXTURE_BINDING_ARRAY | Features::PARTIALLY_BOUND_BINDING_ARRAY | Features::SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING` plus two `max_binding_array_*` limits. After: `Features::empty()` (the `DeviceDescriptor` default) and only `max_buffer_size` set, which was never about the binding array. - **`TextureHandle` has no `primitive()` method any more**; a caller outside `iris` shouldn't have been calling it (it fed the old renderer's internals), but if something did: use `image_index()` for a standalone image's bind-group index. There is no equivalent for a page — a page has no bind group of its own now, see below. - **`GlyphPrimitive` has no public constructor from a struct literal.** Before: `GlyphPrimitive { uv_min, uv_max, view_idx, sampler_idx, color, flags }`. After: `GlyphPrimitive::new(uv_min, uv_max, layer, color, flags)` — one `layer` (the shared atlas array's layer) instead of a `view_idx`/`sampler_idx` pair, since a page is now a layer of one array texture rather than its own bound texture. - **A widget author drawing images is unaffected**: `Painter::texture`/ `texture_at`/`texture_within` and `Textures::add` keep their signatures. What changed underneath is that each standalone image now gets its own `wgpu::BindGroup` and draw call instead of a slot in the shared array — invisible from the widget API, visible only in `UiRenderNode`'s internals and in `iris`'s device requirements.