Crate frust_core 

Layer 1+2 of Frust: the declarative view API, the retained widget tree, box-constraint layout, and the rebuild/layout/paint pass skeleton.

The design mirrors xilem_core’s proven View lifecycle and Masonry’s tree_arena-backed widget tree, but owns its implementation — there is no xilem/masonry dependency and no unsafe in this crate.

Layers

• view — layer 1: the View trait, ChangeFlags, and BuildCtx. Views are cheap descriptors produced by fn build(&mut State) -> impl View<State>.
• widget — layer 2: the Widget trait and its layout/paint/event contexts, the PaintScene paint boundary, and container-owned ChildPod children.
• event — layer 2 input: InputEvent/ PointerEvent and the EventCtx handlers mutate state through.
• input — pure gesture helpers: slop/wheel constants, a VelocityTracker, and the fling-decay math the interactive widgets build on.
• layout — the BoxConstraints box model.
• tree — the WidgetTree arena wrapper, WidgetPod, and the read-only InspectNode walk tooling reads the tree through.
• app — the RenderRoot that drives rebuild → layout → paint. This is what each platform shell owns.
• [component] — Component, Flutter’s StatefulWidget analog: a subtree with retained local state, a per-component reactive Owner, and a state boundary the outer view tree never sees.
• overlay — the overlay portal: an owner-hosted, root-painted, root-routed pod a widget floats above the whole app (menus, popovers, tooltips, selection toolbars).
• selection_toolbar — what a text field publishes when it has a selection, plus the process-global policy/builder slots that decide who draws the toolbar.
• hit — hit-testing helpers for content drawn under an arbitrary kurbo::Affine: the test ChildPod uses for a transformed pod, exposed for canvas hit closures and pan/zoom containers.

Re-exports

pub use anim::AnimationController;

pub use anim::AnimationStatus;

pub use anim::Curve;

pub use anim::FrameTime;

pub use anim::Lerp;

pub use anim::Spring;

pub use anim::SpringDesc;

pub use anim::Tween;

pub use app::Orientation;

pub use app::RenderRoot;

pub use app::WindowMetrics;

pub use component::Component;

pub use component::ComponentView;

pub use component::ComponentWidget;

pub use component::component;

pub use event::CursorIcon;

pub use event::EditCommand;

pub use event::EditingState;

pub use event::EventCtx;

pub use event::EventOutcome;

pub use event::EventResult;

pub use event::ImeContentType;

pub use event::ImeEvent;

pub use event::ImeState;

pub use event::InputEvent;

pub use event::Key;

pub use event::KeyEvent;

pub use event::Modifiers;

pub use event::NamedKey;

pub use event::OverlayEvent;

pub use event::OverlayEventKind;

pub use event::PointerButton;

pub use event::PointerEvent;

pub use event::PointerPhase;

pub use event::ScrollDelta;

pub use event::has_pending_result_flush;

pub use event::mark_focus_orphaned;

pub use event::mark_pending_result_flush;

pub use event::take_focus_orphaned;

pub use event::take_pending_result_flush;

pub use input::FLING_DECAY;

pub use input::FLING_STOP;

pub use input::MOUSE_SLOP;

pub use input::TOUCH_SLOP;

pub use input::VELOCITY_WINDOW_MS;

pub use input::VelocityTracker;

pub use input::WHEEL_LINE_PX;

pub use input::fling_decay;

pub use input::fling_displacement;

pub use insets::CornerInset;

pub use insets::CornerInsets;

pub use insets::EdgeInsets as WindowEdgeInsets;

pub use insets::WindowInsets;

pub use layout::BoxConstraints;

pub use overlay::OutsideTap;

pub use overlay::OverlayBand;

pub use overlay::OverlayEntry;

pub use overlay::OverlayHit;

pub use overlay::OverlayInput;

pub use overlay::OverlayKey;

pub use overlay::OverlayPod;

pub use selection_toolbar::SelectionToolbarActions;

pub use selection_toolbar::SelectionToolbarBuilder;

pub use selection_toolbar::SelectionToolbarPolicy;

pub use selection_toolbar::SelectionToolbarRequest;

pub use selection_toolbar::install_selection_toolbar_builder_if_unset;

pub use selection_toolbar::lock_selection_toolbar_policy;

pub use selection_toolbar::selection_toolbar_builder;

pub use selection_toolbar::selection_toolbar_policy;

pub use selection_toolbar::set_selection_toolbar_builder;

pub use selection_toolbar::set_selection_toolbar_policy;

pub use semantics::SemanticsCtx;

pub use semantics::SemanticsUpdate;

pub use tree::InspectNode;

pub use tree::WidgetPod;

pub use tree::WidgetTree;

pub use view::AnyView;

pub use view::BuildCtx;

pub use view::ChangeFlags;

pub use view::View;

pub use view::WidgetId;

pub use view::any;

pub use widget::ChildPod;

pub use widget::DiscardScene;

pub use widget::HeroDirective;

pub use widget::HeroFrames;

pub use widget::LayoutCtx;

pub use widget::PaintCtx;

pub use widget::PaintOutcome;

pub use widget::PaintScene;

pub use widget::TickClass;

pub use widget::Widget;

pub use accesskit;

Modules

anim

Animation vocabulary: the shared frame clock (FrameTime) plus the pure math widgets consume it through — easing Curves, Tween interpolation, analytic Spring dynamics, and the duration-/spring-driven AnimationController.

app

The render root: the object each platform shell drives each frame.

component

Component: Flutter’s StatefulWidget analog.

event

Layer 2 input: pointer/scroll events and the EventCtx a widget mutates while handling them.

hit

Hit-testing under an arbitrary kurbo::Affine.

input

Pure input/gesture helpers: slop/wheel constants, a trailing-window VelocityTracker, and the fling-decay math (numbers cross-checked against masonry’s implementation).

insets

Window insets: Flutter’s ViewportMetrics inset model ported into the framework core.

layout

Box-constraint layout model.

overlay

The overlay portal: the mechanism a widget anywhere in the tree floats a pod above the whole app with.

selection_toolbar

The selection-toolbar seam: what a text field asks for when it has a selection, and who draws it.

semantics

Layer 2: the semantics seam — a pull-based accessibility tree pass.

tree

The retained widget tree, backed by tree_arena.

view

Layer 1: the declarative View trait.

widget

Layer 2: the retained Widget trait and its layout/paint contexts.

Structs

CornerRadii

The per-corner radii and dash-pattern vocabulary PaintScene’s own signatures name, re-exported from frust-scene so a widget calling PaintScene::fill_rounded_rect_radii/PaintScene::push_clip_rounded_radii/ PaintScene::stroke_path_dashed can name their arguments through the same paint surface it already paints through (mirrors the crate-root accesskit re-export). Per-corner radii for a rounded rectangle, in the pre-transform coordinate space.

DashPattern

The per-corner radii and dash-pattern vocabulary PaintScene’s own signatures name, re-exported from frust-scene so a widget calling PaintScene::fill_rounded_rect_radii/PaintScene::push_clip_rounded_radii/ PaintScene::stroke_path_dashed can name their arguments through the same paint surface it already paints through (mirrors the crate-root accesskit re-export). A stroke’s dash pattern: an on run, an off gap, and a phase offset into that repeating cycle — all lengths in the pre-transform coordinate space.