forked from
jollywhoppers.com/witchsky.app
Bluesky app fork with some witchin' additions 💫
Measure header layout reliably (#2817)
* Measure header layout reliably
* grammar
+21
-16
+21
-16
src/view/com/pager/PagerWithHeader.tsx
+21
-16
src/view/com/pager/PagerWithHeader.tsx
···
233
233
},
234
234
],
235
235
}))
236
-
const headerRef = React.useRef(null)
237
-
React.useEffect(() => {
238
-
// Fire when layout *becomes* ready.
239
-
// We can't rely on onLayout alone because it won't fire if layout is the same.
240
-
// We can't rely on this effect alone because it won't fire if layout changes later.
241
-
if (isHeaderReady) {
242
-
// @ts-ignore
243
-
headerRef.current!.measure(
244
-
(_x: number, _y: number, _width: number, height: number) => {
245
-
onHeaderOnlyLayout(height)
246
-
},
247
-
)
248
-
}
249
-
}, [isHeaderReady, onHeaderOnlyLayout])
250
-
236
+
const pendingHeaderHeight = React.useRef<null | number>(null)
251
237
return (
252
238
<Animated.View
253
239
pointerEvents="box-none"
254
240
style={[styles.tabBarMobile, headerTransform]}>
255
241
<View
256
-
ref={headerRef}
257
242
pointerEvents="box-none"
258
243
collapsable={false}
259
244
onLayout={e => {
260
245
if (isHeaderReady) {
261
246
onHeaderOnlyLayout(e.nativeEvent.layout.height)
247
+
pendingHeaderHeight.current = null
248
+
} else {
249
+
// Stash it away for when `isHeaderReady` turns `true` later.
250
+
pendingHeaderHeight.current = e.nativeEvent.layout.height
262
251
}
263
252
}}>
264
253
{renderHeader?.()}
254
+
{
255
+
// When `isHeaderReady` turns `true`, we want to send the parent layout.
256
+
// However, if that didn't lead to a layout change, parent `onLayout` wouldn't get called again.
257
+
// We're conditionally rendering an empty view so that we can send the last measurement.
258
+
isHeaderReady && (
259
+
<View
260
+
onLayout={() => {
261
+
// We're assuming the parent `onLayout` already ran (parent -> child ordering).
262
+
if (pendingHeaderHeight.current !== null) {
263
+
onHeaderOnlyLayout(pendingHeaderHeight.current)
264
+
pendingHeaderHeight.current = null
265
+
}
266
+
}}
267
+
/>
268
+
)
269
+
}
265
270
</View>
266
271
<View
267
272
onLayout={onTabBarLayout}