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
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
import React, {useCallback, useEffect} from 'react'
import {type NativeScrollEvent} from 'react-native'
import {interpolate, useSharedValue, withSpring} from 'react-native-reanimated'
import EventEmitter from 'eventemitter3'
import {ScrollProvider} from '#/lib/ScrollContext'
import {isNative, isWeb} from '#/platform/detection'
import {useMinimalShellMode} from '#/state/shell'
import {useShellLayout} from '#/state/shell/shell-layout'
const WEB_HIDE_SHELL_THRESHOLD = 200
function clamp(num: number, min: number, max: number) {
'worklet'
return Math.min(Math.max(num, min), max)
}
export function MainScrollProvider({children}: {children: React.ReactNode}) {
const {headerHeight} = useShellLayout()
const {headerMode} = useMinimalShellMode()
const startDragOffset = useSharedValue<number | null>(null)
const startMode = useSharedValue<number | null>(null)
const didJustRestoreScroll = useSharedValue<boolean>(false)
const setMode = React.useCallback(
(v: boolean) => {
'worklet'
headerMode.set(() =>
withSpring(v ? 1 : 0, {
overshootClamping: true,
}),
)
},
[headerMode],
)
useEffect(() => {
if (isWeb) {
return listenToForcedWindowScroll(() => {
startDragOffset.set(null)
startMode.set(null)
didJustRestoreScroll.set(true)
})
}
})
const snapToClosestState = useCallback(
(e: NativeScrollEvent) => {
'worklet'
const offsetY = Math.max(0, e.contentOffset.y)
if (isNative) {
const startDragOffsetValue = startDragOffset.get()
if (startDragOffsetValue === null) {
return
}
const didScrollDown = offsetY > startDragOffsetValue
startDragOffset.set(null)
startMode.set(null)
if (offsetY < headerHeight.get()) {
// If we're close to the top, show the shell.
setMode(false)
} else if (didScrollDown) {
// Showing the bar again on scroll down feels annoying, so don't.
setMode(true)
} else {
// Snap to whichever state is the closest.
setMode(Math.round(headerMode.get()) === 1)
}
}
},
[startDragOffset, startMode, setMode, headerMode, headerHeight],
)
const onBeginDrag = useCallback(
(e: NativeScrollEvent) => {
'worklet'
const offsetY = Math.max(0, e.contentOffset.y)
if (isNative) {
startDragOffset.set(offsetY)
startMode.set(headerMode.get())
}
},
[headerMode, startDragOffset, startMode],
)
const onEndDrag = useCallback(
(e: NativeScrollEvent) => {
'worklet'
if (isNative) {
if (e.velocity && e.velocity.y !== 0) {
// If we detect a velocity, wait for onMomentumEnd to snap.
return
}
snapToClosestState(e)
}
},
[snapToClosestState],
)
const onMomentumEnd = useCallback(
(e: NativeScrollEvent) => {
'worklet'
if (isNative) {
snapToClosestState(e)
}
},
[snapToClosestState],
)
const onScroll = useCallback(
(e: NativeScrollEvent) => {
'worklet'
const offsetY = Math.max(0, e.contentOffset.y)
if (isNative) {
const startDragOffsetValue = startDragOffset.get()
const startModeValue = startMode.get()
if (startDragOffsetValue === null || startModeValue === null) {
if (headerMode.get() !== 0 && offsetY < headerHeight.get()) {
// If we're close enough to the top, always show the shell.
// Even if we're not dragging.
setMode(false)
}
return
}
// The "mode" value is always between 0 and 1.
// Figure out how much to move it based on the current dragged distance.
const dy = offsetY - startDragOffsetValue
const dProgress = interpolate(
dy,
[-headerHeight.get(), headerHeight.get()],
[-1, 1],
)
const newValue = clamp(startModeValue + dProgress, 0, 1)
if (newValue !== headerMode.get()) {
// Manually adjust the value. This won't be (and shouldn't be) animated.
headerMode.set(newValue)
}
} else {
if (didJustRestoreScroll.get()) {
didJustRestoreScroll.set(false)
// Don't hide/show navbar based on scroll restoratoin.
return
}
// On the web, we don't try to follow the drag because we don't know when it ends.
// Instead, show/hide immediately based on whether we're scrolling up or down.
const dy = offsetY - (startDragOffset.get() ?? 0)
startDragOffset.set(offsetY)
if (dy < 0 || offsetY < WEB_HIDE_SHELL_THRESHOLD) {
setMode(false)
} else if (dy > 0) {
setMode(true)
}
}
},
[
headerHeight,
headerMode,
setMode,
startDragOffset,
startMode,
didJustRestoreScroll,
],
)
return (
<ScrollProvider
onBeginDrag={onBeginDrag}
onEndDrag={onEndDrag}
onScroll={onScroll}
onMomentumEnd={onMomentumEnd}>
{children}
</ScrollProvider>
)
}
const emitter = new EventEmitter()
if (isWeb) {
const originalScroll = window.scroll
window.scroll = function () {
emitter.emit('forced-scroll')
return originalScroll.apply(this, arguments as any)
}
const originalScrollTo = window.scrollTo
window.scrollTo = function () {
emitter.emit('forced-scroll')
return originalScrollTo.apply(this, arguments as any)
}
}
function listenToForcedWindowScroll(listener: () => void) {
emitter.addListener('forced-scroll', listener)
return () => {
emitter.removeListener('forced-scroll', listener)
}
}
|
