Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 | 3x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 10x 2x 2x 2x 2x 4x 4x 4x 4x 1x 1x 1x 1x 2x 2x 2x 2x 1x 1x 1x 1x 10x 10x | import {
interpolate,
SharedValue,
useAnimatedReaction,
useAnimatedStyle,
useSharedValue,
withSequence,
withSpring,
withTiming,
} from 'react-native-reanimated';
import { BOOK_PAGE_PEEK_Y, BOOK_PAGE_SCALE_STEP, MAX_ROTATION, PULSE_SPRING } from '../constants';
interface UseStackAnimationProps {
index: number;
currentIndex: number;
animatedValue: SharedValue<number>;
translateX: SharedValue<number>;
translateY: SharedValue<number>;
itemHeight: SharedValue<number>;
width: number;
}
export const useStackAnimation = ({
index,
currentIndex,
animatedValue,
translateX,
translateY,
itemHeight,
width,
}: UseStackAnimationProps) => {
const pulseScale = useSharedValue(1);
useAnimatedReaction(
() => currentIndex === index,
(isTop, wasTop) => {
Iif (isTop && wasTop === false) {
pulseScale.value = withSequence(
withTiming(0.96, { duration: 0 }),
withSpring(1, PULSE_SPRING),
);
}
},
[currentIndex, index],
);
const animatedStyle = useAnimatedStyle(() => {
const currentItem = currentIndex === index;
const relativeIndex = index - currentIndex;
const progress = animatedValue.value - currentIndex;
const clampedProgress = Math.max(0, Math.min(1, progress));
// No clamp — card tilts further as it flies off screen (natural throw feel)
const rotateZ = interpolate(
translateX.value,
[-width * 0.5, 0, width * 0.5],
[MAX_ROTATION * 2.5, 0, -MAX_ROTATION * 2.5],
);
const pivot = -itemHeight.value / 2;
const peekY = BOOK_PAGE_PEEK_Y;
let stackTranslateY = 0;
let stackScale = 1;
let opacity = 1;
switch (relativeIndex) {
case 0:
stackTranslateY = 0;
stackScale = 1;
opacity = 1;
break;
case 1:
// Layer 2: rests peekY below top, slides forward as top card is swiped
stackTranslateY = interpolate(clampedProgress, [0, 1], [peekY, 0]);
stackScale = interpolate(clampedProgress, [0, 1], [1 - BOOK_PAGE_SCALE_STEP, 1]);
opacity = 1;
break;
case 2:
// Layer 3: rests 2×peekY below top, slides to layer 2 position during drag
stackTranslateY = interpolate(clampedProgress, [0, 1], [peekY * 2, peekY]);
stackScale = interpolate(
clampedProgress,
[0, 1],
[1 - BOOK_PAGE_SCALE_STEP * 2, 1 - BOOK_PAGE_SCALE_STEP],
);
opacity = 1;
break;
case 3:
// Layer 4: rests 3×peekY below top, slides to layer 3 position during drag
stackTranslateY = interpolate(clampedProgress, [0, 1], [peekY * 3, peekY * 2]);
stackScale = interpolate(
clampedProgress,
[0, 1],
[1 - BOOK_PAGE_SCALE_STEP * 3, 1 - BOOK_PAGE_SCALE_STEP * 2],
);
opacity = 1;
break;
default:
stackTranslateY = 1000;
stackScale = 0;
opacity = 0;
break;
}
return {
opacity,
transform: [
{ translateX: translateX.value },
{ translateY: translateY.value + stackTranslateY },
{ scale: stackScale * pulseScale.value },
{ translateY: currentItem ? pivot : 0 },
{ rotateZ: currentItem ? `${rotateZ}deg` : '0deg' },
{ translateY: currentItem ? -pivot : 0 },
],
};
});
return animatedStyle;
};
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