The UI system#

The UI is a no_std, allocation-free system for a 240 × 320 display and four buttons. It draws immediately: there is no retained widget tree, and a screen writes the frame it wants.

The screen drawings below are schematics. They explain behavior. They are not pixel captures.

Screen model#

Each Screen variant owns its state by value. One table generates the enum, dispatch, and capabilities. Shared behavior reads those capabilities rather than matching variants:

A screen handles one gesture, returns a transition, and draws the current frame.

Input can change state; drawing receives read-only state and borrowed resources. The screen module owns the interfaces and dispatch. Host drawing generics stop at that boundary.

Navigation#

The screen stack holds at most ten screens, and Home is always the first.

Stack changes cancel incomplete holds. Each screen defines Back: leave an editor, cancel work, change riding view, or pop.

Input#

Release between the tap and hold thresholds cancels the hold. A hold fires at its threshold, so the rider feels when it commits.

The application handles BackHold above the stack. It closes the drawer and opens or reuses the main menu. First-use setup, blocking cards, the recovered-ride card, and confirmed shutdown refuse it until the rider finishes them.

Chords#

Buttons pressed within 100 ms form a chord. It consumes both individual gestures and stays latched until both buttons are released.

Reserved chords consume both presses. The first Up or Down step waits for the chord window; an earlier release steps immediately to keep taps responsive.

Drawers#

Drawers are sheets over the current screen. Opening one replaces the other.

The universal quick drawer descends with brightness, Bluetooth, settings, and power. Brightness appears only on platforms with a controllable backlight.

The contextual drawer rises with the screen's secondary actions. A shared drawer handles input and drawing from a static row table. Without a table, no sheet opens.

Riding views list Up ahead, Detour, POIs, and Routes in that order. Unavailable rows are recessed and inactive. An action replaces the sheet; Back returns to the riding view.

A value row opens an editor with a notch per choice and a committed-value tick. Bike type has four choices. A switch row flips in place.

Screen-specific settings belong in that screen's drawer. A build check rejects duplicate settings bindings, except brightness, Bluetooth, and bike type.

The screen under a drawer is frozen. Only the drawer's facts trigger repaint. Menus dim to separate the sheet from its base. Maps remain undimmed to avoid an expensive redraw.

An incoming card closes the drawer. Dismissing it returns to the underlying screen.

What the map drawer controls#

Map display holds switches for the clock, the scale bar, and the contour layer, and a Map icons menu with switches for peaks, landmarks, and the service categories. Icons stay upright at their source coordinates as the map rotates, and a group appears only at scales where its icons help instead of crowd. Placement takes the nearest unobstructed icon from each enabled group in turn, so one dense category cannot take the screen from the others.

Settlement names have no switch. Each class appears within a scale band, when the place roughly fits the screen. Names disappear when too small or large to help, and avoid each other and visible chrome.

Detour#

Detour leaves the route and comes back to it. It needs a routing graph in the map and a matched position on the route.

Up and Down move the rejoin point ahead. Review compares distance and climb with the replaced stretch. Committing preserves completed geometry and inserts the detour.

Hold to confirm#

A destructive action requires a hold, and the row draws its progress. The action runs only when the hold reaches its threshold.

Delete lives on one row. A hold anywhere else deletes nothing.

Ride Assistant#

Hold Up + Select to open Ride Assistant over the riding view. It closes previous pages and cancels their searches or pending detours. Back returns to the ride. Find a place, What is next, Nearby landmarks, and Easier routes use installed offline data.

Help#

Open Help in Assistant, or hold Up + Down for two seconds. Help shows 112 and the GPS position in WGS84 decimal degrees and degrees, minutes and seconds. The fix age and status distinguish a current position from the last known position. Coordinates work without a map. A map can add a nearby settlement and a calibrated height.

Help stays open until the rider leaves. Select starts or stops the distress signal. The signal plays at Loud, even with Sound off. Leaving Help stops it. It sounds six times in one minute, then stays quiet for one minute, and repeats. Use a phone to call; the device does not contact emergency services.

Find a place#

Find alternates nearby places with places along the next route stretch. It calculates outward and return legs, then composes the full route when a result opens. The drawer sets the result count; the default is four.

Places known to be closed now are hidden, which the rider can turn off for every category at once. A place with unknown hours stays in the list and is never labelled open. Opening hours are information: they never block a preview, and the device reports the status now, not a guess at the status on arrival.

With a route, review compares the visit, return and remaining journey against the original remainder. Without a route, the place is a direct destination. Acceptance starts recording if needed; browsing changes nothing.

A place is routable only where the map gives it a mapped approach. A straight-line distance never promises a rideable connection.

What is next#

The line shows the remaining route, with places ahead below the rider. Settlements group nearby services; waypoints and the route end stay visible through filters. Larger spaces mark long distances between stops. Select opens details. Hold refreshes the list. Service records follow the map format.

Nearby landmarks#

Landmarks keeps a stable page of nearby sites. Select opens text and an available photo. Down + Back opens sources, so credits travel with content. Closed sites stay readable and visitable from outside.

Easier routes#

Easier routes runs bounded searches for less climbing, smoother surfaces, and shorter distance under the rider's bike profile. Results must improve their goal within an added-cost bound; discovery is not exhaustive.

The comparison camera stays fixed. Select opens a current-and-new table. Use this route accepts it and keeps recording. Shorter distance does not promise shorter time; the device has no arrival model.

POI browser#

The POI menu lists the service categories, and a category returns pages of nearby places.

The page and its order are fixed while the list is open, so a list does not reorder under a rider's thumb as the position updates. Only the bearing arrow follows the live fix.

The detail screen reads the schedule once and calculates today's state from the local clock. A definite open or closed answer needs a trusted clock and a known local offset. Anything else is Unknown.

Settings#

Pages sit under one hub, every page a list of rows in the drawers' grammar:

A changed value is written when the rider leaves the Settings subtree, not once per step.

Settings do not live on the card, so they survive a card change. The UI languages are English, German, French, and Spanish, and the build generates the translation table from four catalogs and fails on a missing or extra key.

Route cleanup#

The device deletes nothing by itself. When a route upload fails because storage is full, it offers cleanup: choose an age in weeks and hold to confirm. Cleanup keeps the active route, routes newer than that age, and routes whose date is unknown, because an unknown date is not evidence that a route is old. See ride reconciliation.

Repaint policy#

Rendering is on demand. A static screen with no input, data change, or timer stays idle.

The render key#

Each screen declares its drawing facts. Frame work compares them before and after, then repaints changed regions. A new heart rate updates its grid and map effort band. Local state, such as a selection, requests repaint directly. Extra repaint is safe; missing repaint is a defect.

The overlay presenter reads the clean base frame, adds the overlay, and leaves the base frame unchanged.

Screens the companion pushes#

The companion can open modal cards for pairing, route and trip updates, and warnings. The scheduler gives each type a fixed priority, and a new card never replaces a hold in progress. The passkey card cannot be dismissed before pairing ends.

Riding data#

Climbs#

The route processor supplies the climb segments and their profiles. Climb joins the riding views only while a climb is active.

Waypoints#

Waypoints come from the route file, and Navigator tracks the next one from the matched position. The map, route, and statistics views place them on the same route-distance axis, so a waypoint is at the same progress in all three.

Up ahead#

Nearby POIs use the distance through the air. Up ahead uses the distance along the route, which is the distance a rider actually has to ride.

Each corridor pass adds one row at its nearest point. Leaving and returning adds another encounter; a road bend does not.

A saved cursor applies only to its list. Changing filters selects the first row still ahead, so a previous scroll cannot skip nearer matches.

Main rider flow#

Home opens the main menu, a route selection opens its overview, and Start opens Map on a clean ride stack. During a ride, Back cycles the riding views, a press pauses, and Back-hold reaches the main menu. Map Inspect is entered with a Select hold, and Back leaves Inspect before it changes views. Idle return removes abandoned chrome: it returns to Home when there is no ride, and to Map during one.

Visual vocabulary#

Each shared mechanism has one owner, one module per concept under screen/vocab/:

Long names end in two dots. One selected name per frame can scroll: a list row, detail title, or Peak View peak. Monospace fonts scroll by substring. The riding waypoint tile scrolls once per name change, then rests.

Palette constants are written once and converted to the panel's 64 colors by the framebuffer, so a screen never picks a device color by hand.

Adding a screen#

One module and one row declare a screen. The row alone does not put it on the glass:

The acceptance test is the copy-fit gate over every reachable screen and language.

Source map#

See system architecture for the host loop and rendering pipeline for pixel generation.