Merge branch 'custom-algos' of github.com:bluesky-social/social-app into custom-algos

1 files changed, 84 insertions, 0 deletions

diff --git a/src/lib/hooks/useDraggableScrollView.ts b/src/lib/hooks/useDraggableScrollView.ts
new file mode 100644
index 000000000..b0f7465d7
--- /dev/null
+++ b/src/lib/hooks/useDraggableScrollView.ts
@@ -0,0 +1,84 @@
+import {useEffect, useRef, useMemo, ForwardedRef} from 'react'
+import {Platform, findNodeHandle} from 'react-native'
+import type {ScrollView} from 'react-native'
+import {mergeRefs} from 'lib/merge-refs'
+
+type Props<Scrollable extends ScrollView = ScrollView> = {
+  cursor?: string
+  outerRef?: ForwardedRef<Scrollable>
+}
+
+export function useDraggableScroll<Scrollable extends ScrollView = ScrollView>({
+  outerRef,
+  cursor = 'grab',
+}: Props<Scrollable> = {}) {
+  const ref = useRef<Scrollable>(null)
+
+  useEffect(() => {
+    if (Platform.OS !== 'web' || !ref.current) {
+      return
+    }
+    const slider = findNodeHandle(ref.current) as unknown as HTMLDivElement
+    if (!slider) {
+      return
+    }
+    let isDragging = false
+    let isMouseDown = false
+    let startX = 0
+    let scrollLeft = 0
+
+    const mouseDown = (e: MouseEvent) => {
+      isMouseDown = true
+      startX = e.pageX - slider.offsetLeft
+      scrollLeft = slider.scrollLeft
+
+      slider.style.cursor = cursor
+    }
+
+    const mouseUp = () => {
+      if (isDragging) {
+        slider.addEventListener('click', e => e.stopPropagation(), {once: true})
+      }
+
+      isMouseDown = false
+      isDragging = false
+      slider.style.cursor = 'default'
+    }
+
+    const mouseMove = (e: MouseEvent) => {
+      if (!isMouseDown) {
+        return
+      }
+
+      // Require n pixels momement before start of drag (3 in this case )
+      const x = e.pageX - slider.offsetLeft
+      if (Math.abs(x - startX) < 3) {
+        return
+      }
+
+      isDragging = true
+      e.preventDefault()
+      const walk = x - startX
+      slider.scrollLeft = scrollLeft - walk
+    }
+
+    slider.addEventListener('mousedown', mouseDown)
+    window.addEventListener('mouseup', mouseUp)
+    window.addEventListener('mousemove', mouseMove)
+
+    return () => {
+      slider.removeEventListener('mousedown', mouseDown)
+      window.removeEventListener('mouseup', mouseUp)
+      window.removeEventListener('mousemove', mouseMove)
+    }
+  }, [cursor])
+
+  const refs = useMemo(
+    () => mergeRefs(outerRef ? [ref, outerRef] : [ref]),
+    [ref, outerRef],
+  )
+
+  return {
+    refs,
+  }
+}