Working overlay, WIP

src/components/Tooltip/index.tsx

···
+import {
+  useMemo,
+  useRef,
+  createContext,
+  useContext,
+  useState,
+  isValidElement,
+} from 'react'
+import {View, Modal, Dimensions, Pressable} from 'react-native'
+import {useSafeAreaInsets} from 'react-native-safe-area-context'
+import flattenReactChildren from 'react-keyed-flatten-children'
+
+import {Portal} from '#/components/Portal'
+import {atoms as a, useTheme} from '#/alf'
+
+type Context = {
+  visible: boolean
+  onVisibleChange: (visible: boolean) => void
+  targetMeasurements:
+    | {
+        x: number
+        y: number
+        width: number
+        height: number
+      }
+    | undefined
+  targetRef: React.RefObject<View>
+  targetElement: any
+}
+
+const TooltipContext = createContext<Context>({
+  visible: false,
+  onVisibleChange: () => {},
+  targetMeasurements: undefined,
+  targetRef: {current: null},
+  targetElement: null,
+})
+
+export function Outer({
+  children,
+  visible: requestVisible,
+  onVisibleChange,
+}: {
+  children: React.ReactNode
+  visible: boolean
+  onVisibleChange: (visible: boolean) => void
+}) {
+  const targetRef = useRef<View>(null)
+  const [prevRequestVisible, setPrevRequestVisible] = useState<
+    boolean | undefined
+  >()
+  const [visible, setVisible] = useState(false)
+  const [measurements, setMeasurements] = useState<
+    | {
+        x: number
+        y: number
+        width: number
+        height: number
+      }
+    | undefined
+  >(undefined)
+
+  if (requestVisible && !prevRequestVisible) {
+    setPrevRequestVisible(requestVisible)
+    if (targetRef.current) {
+      targetRef.current.measure((_x, _y, width, height, pageX, pageY) => {
+        setMeasurements({x: pageX, y: pageY, width, height})
+        setVisible(true)
+      })
+    }
+  } else if (!requestVisible && prevRequestVisible) {
+    setPrevRequestVisible(requestVisible)
+    setMeasurements(undefined)
+    setVisible(false)
+  }
+
+  const ctx = useMemo(
+    () => ({
+      visible,
+      onVisibleChange,
+      targetMeasurements: measurements,
+      targetRef,
+      targetElement: flattenReactChildren(children).find(child => {
+        if (isValidElement(child) && child.type === Target) {
+          return true
+        }
+      }),
+    }),
+    [visible, onVisibleChange, measurements, targetRef],
+  )
+
+  return (
+    <TooltipContext.Provider value={ctx}>{children}</TooltipContext.Provider>
+  )
+}
+
+export function Target({
+  children,
+}: {
+  children: (props: {ref: Context['targetRef']}) => React.ReactNode
+}) {
+  const {targetRef} = useContext(TooltipContext)
+
+  return children({
+    ref: targetRef,
+  })
+}
+
+const TIP_SIZE = 12
+
+export function Content({children}: {children: React.ReactNode}) {
+  const t = useTheme()
+  const {visible, onVisibleChange, targetMeasurements, targetElement} =
+    useContext(TooltipContext)
+  const [ready, setReady] = useState(false)
+  const [measurements, setMeasurements] = useState<
+    | {
+        width: number
+        height: number
+      }
+    | undefined
+  >(undefined)
+  const safe = useSafeAreaInsets()
+
+  const requestClose = () => {
+    onVisibleChange(false)
+    setReady(false)
+    setMeasurements(undefined)
+  }
+
+  const {positionTop, contentLeft, tipTop, tipLeft} = useMemo(() => {
+    if (!targetMeasurements || !measurements)
+      return {
+        positionTop: 0,
+        contentLeft: 0,
+        tipTop: 0,
+        tipLeft: 0,
+      }
+
+    const win = Dimensions.get('window')
+    const {width: ww, height: wh} = win
+    const maxTop = safe.top
+    const maxBottom = wh - safe.bottom
+    const {width: cw, height: ch} = measurements
+    const minLeft = a.px_xl.paddingLeft
+    const maxLeft = ww - minLeft
+
+    let positionTop = targetMeasurements.y + targetMeasurements.height
+    let contentLeft = Math.max(
+      minLeft,
+      targetMeasurements.x + targetMeasurements.width / 2 - cw / 2,
+    )
+    let tipTop = (TIP_SIZE / 2) * -1
+    let tipLeft =
+      targetMeasurements.x + targetMeasurements.width / 2 - TIP_SIZE / 2
+
+    if (contentLeft + cw > maxLeft) {
+      contentLeft -= contentLeft + cw - maxLeft
+    }
+
+    positionTop += TIP_SIZE / 3
+
+    return {
+      positionTop,
+      contentLeft,
+      tipTop,
+      tipLeft,
+    }
+  }, [targetMeasurements, measurements, safe])
+
+  if (!visible || !targetMeasurements) return null
+
+  return (
+    <Portal>
+      <Modal
+        transparent
+        onRequestClose={() => {}} // TODO
+        style={[a.absolute, a.inset_0]}>
+        {/* Backdrop */}
+        <Pressable
+          style={[
+            a.absolute,
+            a.inset_0,
+            t.atoms.bg,
+            {
+              opacity: 0.4,
+            },
+          ]}
+          onPress={requestClose}
+        />
+
+        {/* Replica of the target element */}
+        <View
+          style={[
+            a.absolute,
+            {
+              top: targetMeasurements.y,
+              left: targetMeasurements.x,
+              height: targetMeasurements.height,
+              width: targetMeasurements.width,
+            },
+          ]}>
+          {targetElement}
+        </View>
+
+        {/* Outer content container */}
+        <View
+          style={[
+            a.absolute,
+            a.align_start,
+            {
+              opacity: ready ? 1 : 0,
+              top: positionTop,
+              left: 0,
+              right: 0,
+            },
+          ]}>
+          {/* The triangle "tip" */}
+          <View
+            style={[
+              a.absolute,
+              a.top_0,
+              a.z_10,
+              t.atoms.bg,
+              {
+                borderTopLeftRadius: a.rounded_xs.borderRadius,
+                width: TIP_SIZE,
+                height: TIP_SIZE,
+                transform: [{rotate: '45deg'}],
+                top: tipTop,
+                left: tipLeft,
+              },
+            ]}
+          />
+
+          {/* The content itself */}
+          <View
+            style={[
+              a.px_md,
+              a.py_sm,
+              a.rounded_sm,
+              t.atoms.bg,
+              t.atoms.shadow_sm,
+              {
+                maxWidth: 200,
+                left: contentLeft,
+              },
+            ]}
+            onLayout={e => {
+              setReady(true)
+              setMeasurements({
+                width: e.nativeEvent.layout.width,
+                height: e.nativeEvent.layout.height,
+              })
+            }}>
+            {children}
+          </View>
+        </View>
+      </Modal>
+    </Portal>
+  )
+}

src/screens/Profile/Header/ProfileHeaderStandard.tsx

···
 import {ProfileHeaderHandle} from './Handle'
 import {ProfileHeaderMetrics} from './Metrics'
 import {ProfileHeaderShell} from './Shell'
+import * as Tooltip from '#/components/Tooltip'
 
 interface Props {
   profile: AppBskyActorDefs.ProfileViewDetailed
···
 
   const {isActive: live} = useActorStatus(profile)
 
+  const [visible, setVisible] = React.useState(false)
+
   return (
     <ProfileHeaderShell
       profile={profile}
···
             )
           ) : !profile.viewer?.blockedBy ? (
             <>
-              {hasSession && <MessageProfileButton profile={profile} />}
+              <Button
+                label='test'
+                size='small'
+                variant='solid'
+                color='secondary'
+                shape='round'
+                onPress={() => setVisible(!visible)}
+              >
+                <ButtonIcon position="left" icon={Plus} />
+              </Button>
 
               <Button
                 testID={profile.viewer?.following ? 'unfollowBtn' : 'followBtn'}
···
                   )}
                 </ButtonText>
               </Button>
+
+
+              {hasSession && (
+                <>
+                  <Tooltip.Outer visible={visible} onVisibleChange={setVisible}>
+                    <Tooltip.Target>
+                      {({ref}) => (
+                        <View ref={ref}>
+                          <MessageProfileButton profile={profile} />
+                        </View>
+                      )}
+                    </Tooltip.Target>
+                    <Tooltip.Content>
+                      <Text>The quick brown fox jumps over the lazy dog</Text>
+                    </Tooltip.Content>
+                  </Tooltip.Outer>
+                </>
+              )}
             </>
           ) : null}
           <ProfileMenu profile={profile} />