embedded-gui

embedded-gui is a no_std GUI/HUD crate for embedded-graphics displays. It is built around fixed-capacity data structures, deterministic rendering, and embedded-friendly interaction patterns (pointer, encoder, and keyboard-style input).

Heavily inspired by the Pebble smartwatch UI framework — its animation model, interaction contracts, and cinematic motion primitives draw directly from Pebble's design language. LVGL is a secondary influence, particularly for widget composition and style-state conventions.

Current State

embedded-gui currently provides a broad baseline of widgets, interaction semantics, fixed-capacity animation primitives, and screen transition tooling for embedded UIs. Recent work has focused on tightening interaction fidelity, expanding state transition coverage, and improving regression-focused examples/docs.

• Pointer release semantics now consistently target the originally pressed widget.
• Focused open dropdowns now close on Back before global back handling.
• State transitions now cover keyboard and pointer press feedback paths.
• Enabled/disabled flag changes now participate in state transitions with regression coverage.
• Style-class state overrides now participate correctly in transition endpoint blending.
• Select activation now supports configurable double-select recognition (DoubleClicked events).
• Per-widget raw key input policy now supports SelectPressed/Released and BackPressed/Released.
• Pointer interaction now supports configurable double-click recognition (DoubleClicked events).
• Per-widget key bindings can override Select/Back behavior (Default, Ignore, Activate, Back).
• Textarea no-op edits avoid emitting mutation events, with regression coverage.
• Wrapped-line selection navigation (SelectHome/SelectEnd) now has dedicated edge-case coverage.
• Cross-widget interaction matrix coverage now includes dropdown/list/tabs/roller keyboard navigation paths.
• Nested layout + clip behavior now has dedicated regression coverage for parent-relative composition.
• A dedicated interaction semantics simulator example is available in examples/interaction_semantics_showcase.rs.

Quick Start

use embedded_gui::prelude::*;

let mut gui = GuiContext::<8, 4, 8>::new(Rect::new(0, 0, 128, 64));
gui.add_label(Rect::new(4, 4, 80, 8), "READY", Style::label())?;
gui.add_progress_bar(Rect::new(4, 18, 80, 8), 0.6, Style::progress())?;
gui.render(&mut display)?;

Implemented Feature Surface

Widgets and primitives

The current widget set includes:

• labels, panels, buttons, icon buttons, borders/spacers
• progress bars, sliders, toggles, checkboxes, value labels
• lists, menus, tabs, dialogs, toasts, scroll views
• dropdowns, rollers, tables
• chart (line and bars), spinner, meter/gauge/arc gauge/needle
• textareas and on-screen keyboards
• image widgets (ImageRef, ImageFit, atlas/sprite helpers)

Input and events

• InputEvent supports D-pad/encoder navigation, pointer events, and text-editing-oriented key events
• UI-level events (UiEvent) and widget-level events (WidgetEvent) are both exposed
• Event flow supports capture, target, and bubble phases with filterable dispatch policy hooks
• Pointer semantics include long-press, gesture dispatch, drag scrolling, inertia, and press-repeat timing hooks

Layout, styling, and text

• LinearLayout and constraint-based item layout (Length, Min/Max, Percent, Ratio, Fill)
• Style model with stateful variants (normal, focused, pressed, disabled)
• Style interpolation and transition primitives (StyleTransition, lerp_style)
• Text layout primitives (Span, Line, Text) with alignment, wrapping, spacing, overflow controls
• Text shaping interface (TextShaper) with a basic shaping implementation for embedded-safe defaults

Animation and transitions

• Core animation manager and easing/tween/path/spring/inertia primitives
• Spatial timing (moook_curve, TransitionPreset) — see docs/transition-presets.md
• Widget property animation (WidgetAnimator) and preset helpers (presets)
• Timeline/keyframe sequencing support (AnimationSequence, SequencePlayer)
• Screen stack + transition primitives for app-level flows (fade, slide, wipe, shutter, port-hole, round-flip, modal)

Animation Quickstart

embedded-gui includes fixed-capacity animation primitives that stay no_std friendly.

use embedded_gui::prelude::*;

let mut animator = WidgetAnimator::<8, 8>::new();
let progress = gui.add_progress_bar(Rect::new(4, 18, 80, 8), 0.0, Style::progress())?;
animator.animate_progress(progress, 0.0, 1.0, 600, Easing::InOutSine)?;

// In your frame loop:
animator.tick(16, &mut gui)?;
gui.render_dirty(&mut display)?;
gui.clear_dirty();

Textarea Editing Input

Textarea widgets support editor-style navigation and mutation events, including:

• InputEvent::WordLeft / InputEvent::WordRight
• InputEvent::Home / InputEvent::End
• InputEvent::Select* expansion variants
• InputEvent::Undo / InputEvent::Redo
• selection-replace behavior on typing/backspace/delete

See docs/textarea-input-keybindings.md for mappings and loop snippets.

Font Glyph Overrides

The build pipeline supports external glyph overrides from:

• assets/fonts/ascii_3x5.txt
• assets/fonts/ascii_4x7.txt

Format per line:

key:row0,row1,row2,row3,row4

• key: a single character or space
• each row: 3 bits using 0/1 (left to right)
• blank lines and # comments are ignored

Example:

?:111,001,010,000,010
!:010,010,010,000,010
space:000,000,000,000,000

Unspecified glyphs fall back to built-in defaults in build.rs.

Preview helper:

python3 scripts/preview_glyphs.py assets/fonts/ascii_3x5.txt "?!@"

Examples

The examples/ folder currently includes:

• widgets_showcase.rs
• dashboard_app.rs
• simulator_menu.rs
• event_dispatch_showcase.rs
• interaction_semantics_showcase.rs
• raw_key_input_showcase.rs
• form_flow_showcase.rs
• complex_layout_showcase.rs
• input_gesture_drag_repeat_showcase.rs
• long_press_input_showcase.rs
• text_layout_showcase.rs
• font_text_model_showcase.rs
• animation_motion_showcase.rs
• animation_kitchen_sink_showcase.rs
• animation_dirty_showcase.rs
• timeline_transition_showcase.rs
• visual_quality_showcase.rs
• embedded_3dgfx_overlay.rs

Behavior Notes

• Input and widget interaction guarantees are documented in docs/interaction-behavior-contract.md.

Visual Showcase

Animation and transition capabilities (generated from simulator output):

Flip-card screen transition (RoundFlipLeft) — card selection between views:

Cinematic peek/glance/carddeck — launcher-style glance tiles cycling with slide-prominence animation, peek reveal, and card story transitions:

Dashboard-style UI composition:

Typography and mixed-font text model:

Static motion frame preview: