What Is an Embedded GUI Widget Library?

The Slider widget lets users select a value from a continuous range by dragging a handle along a track. Available in horizontal and vertical orientations. Configurable min/max range, step size, and fill colour. Used for volume, brightness, temperature, and speed controls. Supports both touch drag and encoder-based increment. The SLD widget API provides four event sub-types — press, drag, release, value-change — enabling precise application response at every interaction stage.

The RotaryKnob widget renders a skeuomorphic dial control for adjusting values by rotating a virtual knob — ideal for applications that mimic physical controls such as audio equalisers, HVAC thermostats, and instrument cluster settings. Supports configurable start/end angle, min/max value, and directional touch or encoder input. Smooth angular animation is rendered entirely in software, with optional hardware-acceleration on platforms with 2D GPU support. A natural fit for automotive HMI and industrial control panels.

The TextEdit widget provides a configurable text input field that integrates directly with Sparklet's Keyboard and KeyboardKey widgets. Flint ships pre-built QWERTY and numeric OSK layouts — both fully customisable for language, branding, and key mapping. On activation, the keyboard appears automatically and dismisses on commit or cancel. Supports password masking, max-length enforcement, and placeholder text. Used in appliance PIN entry, industrial login screens, and medical device patient ID fields.

CheckBox provides binary state selection — checked or unchecked — with configurable tick icons and label text. Supports grouped multi-select patterns for settings screens. SwipeButton is a slide-to-confirm control used for safety-critical actions (e.g., start engine, initiate purge, confirm wipe) where accidental activation must be prevented. The user drags a thumb across the full track to confirm, preventing single-tap false triggers common on vibration-prone industrial hardware.

The Meter widget renders a circular gauge — speedometer, tachometer, pressure dial, battery level indicator — with a configurable needle, arc, tick marks, and colour-coded zones (green/yellow/red). Needle sweep is animated and GPU-assisted on accelerated platforms. Fully configurable value range, scale divisions, and label formatting. A standard component in automotive instrument clusters, medical vital sign displays, and industrial process monitors. The Sparklet Meter widget is designed for precise, low-latency needle updates driven directly from hardware sensor interrupts or RTOS queue messages.

The ProgressBar widget comes in two forms: Linear (horizontal or vertical fill bar) and Circular (radial arc fill). Both support percentage-based or value-range modes. Linear progress bars are used for file transfer progress, installation status, and battery charge indication. Circular variants are used for compact dashboards, wearable device charge displays, and loading indicators where screen real estate is limited. This is one of the most frequently used progress bar widget MCU implementations — optimised to render with a single fill-rect or arc draw operation per frame.

The Clock widget renders an analog clockface with configurable hour, minute, and second hands, tick marks, and dial artwork. Hand rotation is calculated from a time value provided by the application — Sparklet does not manage RTC directly; the application feeds current time via the widget API. Ideal for home automation control panels, industrial operator stations, and consumer appliance displays. The clock face artwork, hand shapes, and colours are all set through Flint Designer as standard image and colour properties — no code required to style.

Static is the fundamental read-only display widget — a configurable text label with full font, colour, alignment, and overflow control (clip, ellipsis, marquee scrolling). Used for titles, status text, sensor readouts, and unit labels everywhere on a display. TextArea is the multi-line scrollable text display — used for log outputs, notifications, descriptive panels, and manual pages within embedded applications. Both widgets support Unicode and multi-language content when used with Sparklet's multi-language font engine.

GridView arranges child widgets in a configurable row-and-column grid layout — supporting both fixed-size cells and proportional allocation. Used for icon grids, app launchers, settings dashboards, and product catalogues on appliance displays. Supports horizontal and vertical scroll directions. Sparklet's GridView handles child widget creation, positioning, and recycling automatically as the user scrolls, keeping RAM usage bounded regardless of grid content count.

The Carousel widget presents a horizontally or vertically swipeable collection of views — product images, onboarding screens, mode selector panels, or feature highlights. Smooth paged scrolling with inertia and snap animation. The DotNavigator widget renders the familiar pager dots aligned to the active carousel page, updating automatically as the user swipes. This Carousel + DotNavigator pairing is the standard pattern for home screens on smart appliances, wearable setup flows, and consumer electronics mode selection.

Dialog presents a modal overlay window for confirmations, alerts, and user prompts — interrupting the main UI flow and requiring an explicit user action to dismiss. Supports configurable button sets, custom content areas, and callback functions on button press. MsgBox is a lighter-weight non-modal notification popup for transient messages (success, warning, error) that auto-dismiss after a configurable timeout or on tap. Both are essential for safety-critical applications where the operator must acknowledge critical state changes before proceeding.

Tab provides a tabbed navigation bar that switches between content panels — the standard pattern for multi-section settings screens, feature dashboards, and instrument cluster view modes. Menu renders a hierarchical dropdown or sidebar navigation structure. ListBox and ListView render scrollable selection lists with single or multi-select modes — used for file selectors, device lists, network SSIDs, and configuration option pickers. ComboBox combines a collapsed display with a dropdown list, saving screen space in dense configuration UIs.