Implement Dokio screens from the design doc (turns 3 + 4)

Scaffold an Expo + TypeScript app for Dokio, the app that scans
Behördenpost and explains it in plain language, and build the four
screens specified in "Dokio Design.dc.html":

  4a  Onboarding, full-bleed dither gradient
  4b  Home, dithered scan card
  3a  Kamera, mocked viewfinder
  3b  Archiv, search + filters + month groups

Design tokens from the turn 4 blue palette live in src/theme.ts.
Content is mocked in src/data/letters.ts, taken verbatim from the doc.

DitherBackground is a GLSL port of the doc's dither-bg.js, which drew a
low-resolution canvas and upscaled it with image-rendering: pixelated;
the fragment shader snaps to the same grid instead. Two notes on the
port:

- The original's fract(sin(x) * 43758.5453) hash only distributes well
  in float64. A fragment shader's highp float has ~24 mantissa bits, so
  it collapsed to a near-constant field and the gradient bands rendered
  straight rather than warped. Replaced with Hoskins' hash, verified
  against the original running side by side.
- The 4x4 Bayer matrix is built recursively rather than as a lookup,
  which avoids dynamic array indexing; the construction reproduces all
  16 entries of the original exactly.

The camera screen deliberately stops short of expo-camera: the
viewfinder is a static stand-in, so the flow is navigable without
permissions. The 2a result screen is not part of turns 3 and 4 and is
not included.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-07-20 14:48:50 +02:00
commit 66bdf646ae
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import { useRouter } from 'expo-router';
import { Pressable, ScrollView, StyleSheet, Text, View } from 'react-native';
import { useSafeAreaInsets } from 'react-native-safe-area-context';
import { DitherBackground } from '../../src/components/DitherBackground';
import { CameraIcon } from '../../src/components/Icons';
import { LetterRow } from '../../src/components/LetterRow';
import { letters } from '../../src/data/letters';
import { colors, font, glow, radius, shadow, space } from '../../src/theme';
/** Home, design option 4b: the scan card carries the dither gradient. */
export default function Home() {
const router = useRouter();
const insets = useSafeAreaInsets();
const openDeadline = letters.find((l) => l.deadlineDays !== undefined);
return (
<View style={styles.screen}>
<ScrollView
contentContainerStyle={{ paddingTop: insets.top + 24, paddingBottom: 24 }}
showsVerticalScrollIndicator={false}
>
<View style={styles.header}>
<Text style={styles.greeting}>Hallo Lena!</Text>
<Text style={styles.greetingSub}>Ein neuer Brief? Kein Stress wir helfen dir.</Text>
</View>
<Pressable
style={({ pressed }) => [styles.scanCard, pressed && styles.pressed]}
onPress={() => router.push('/scan')}
accessibilityRole="button"
accessibilityLabel="Brief scannen"
>
<DitherBackground
color1={colors.blueDeep}
color2={colors.blueHaze}
speed={1}
pixel={2.5}
style={styles.scanCardBg}
/>
<View style={styles.scanCardRow}>
<View style={styles.scanIcon}>
<CameraIcon size={28} />
</View>
<View style={styles.scanCardText}>
<Text style={styles.scanTitle}>Brief scannen</Text>
<Text style={styles.scanSub}>Foto machen, fertig!</Text>
</View>
</View>
<View style={styles.scanCta}>
<Text style={styles.scanCtaLabel}>Los geht's</Text>
</View>
</Pressable>
<View style={styles.stats}>
<View style={styles.stat}>
<Text style={[styles.statNumber, { color: colors.blueDeep }]}>
{letters.filter((l) => l.deadlineDays !== undefined).length}
</Text>
<Text style={styles.statLabel}>Frist offen</Text>
<Text style={styles.statHint}>
{openDeadline ? `noch ${openDeadline.deadlineDays} Tage` : 'alles erledigt'}
</Text>
</View>
<View style={styles.stat}>
<Text style={[styles.statNumber, { color: colors.blueSoft }]}>{letters.length}</Text>
<Text style={styles.statLabel}>Briefe erklärt</Text>
<Text style={styles.statHint}>alles im Archiv</Text>
</View>
</View>
<View style={styles.listHeader}>
<Text style={styles.listTitle}>Deine Briefe</Text>
<Pressable onPress={() => router.push('/(tabs)/archive')} hitSlop={10}>
<Text style={styles.listAll}>Alle </Text>
</Pressable>
</View>
<View style={styles.list}>
{letters.slice(0, 2).map((letter) => (
<LetterRow key={letter.id} letter={letter} />
))}
</View>
</ScrollView>
</View>
);
}
const styles = StyleSheet.create({
screen: { flex: 1, backgroundColor: colors.canvas },
pressed: { opacity: 0.9 },
header: { paddingHorizontal: space.gutter },
greeting: { fontFamily: font.display, fontSize: 28, letterSpacing: -0.5, color: colors.ink },
greetingSub: { fontFamily: font.semibold, fontSize: 15, color: colors.slate, marginTop: 3 },
scanCard: {
marginHorizontal: space.gutter,
marginTop: 20,
borderRadius: radius['4xl'],
paddingVertical: 26,
paddingHorizontal: 24,
overflow: 'hidden',
backgroundColor: colors.blueDeep,
...shadow.blueCard,
},
scanCardBg: { borderRadius: radius['4xl'] },
scanCardRow: { flexDirection: 'row', alignItems: 'center', gap: 14 },
scanIcon: {
width: 56,
height: 56,
borderRadius: 28,
backgroundColor: 'rgba(255,255,255,0.22)',
alignItems: 'center',
justifyContent: 'center',
},
scanCardText: { flex: 1 },
scanTitle: { fontFamily: font.display, fontSize: 22, color: colors.onBlue, ...glow },
scanSub: { fontFamily: font.bold, fontSize: 14, color: colors.onBlue, marginTop: 2, ...glow },
scanCta: {
marginTop: 18,
backgroundColor: '#FFFFFF',
borderRadius: radius.lg,
paddingVertical: 14,
alignItems: 'center',
},
scanCtaLabel: { fontFamily: font.extrabold, fontSize: 16, color: colors.blueDeep },
stats: { flexDirection: 'row', gap: 10, marginHorizontal: space.gutter, marginTop: 14 },
stat: {
flex: 1,
backgroundColor: colors.surface,
borderRadius: radius['2xl'],
paddingVertical: 14,
paddingHorizontal: 16,
...shadow.card,
},
statNumber: { fontFamily: font.display, fontSize: 22 },
statLabel: { fontFamily: font.bold, fontSize: 12.5, color: colors.ink, marginTop: 2 },
statHint: { fontFamily: font.regular, fontSize: 11.5, color: colors.slate },
listHeader: {
flexDirection: 'row',
justifyContent: 'space-between',
alignItems: 'baseline',
paddingHorizontal: space.gutter,
marginTop: 22,
},
listTitle: { fontFamily: font.display, fontSize: 17, color: colors.ink },
listAll: { fontFamily: font.extrabold, fontSize: 13, color: colors.blueDeep },
list: { gap: 9, paddingHorizontal: space.gutter, marginTop: 12 },
});