fix(app): safety triangle for sidebar hover (#12179)

1 files changed, 138 insertions, 0 deletions

diff --git a/packages/app/src/utils/aim.ts b/packages/app/src/utils/aim.ts
new file mode 100644
index 000000000..23471959e
--- /dev/null
+++ b/packages/app/src/utils/aim.ts
@@ -0,0 +1,138 @@
+type Point = { x: number; y: number }
+
+export function createAim(props: {
+  enabled: () => boolean
+  active: () => string | undefined
+  el: () => HTMLElement | undefined
+  onActivate: (id: string) => void
+  delay?: number
+  max?: number
+  tolerance?: number
+  edge?: number
+}) {
+  const state = {
+    locs: [] as Point[],
+    timer: undefined as number | undefined,
+    pending: undefined as string | undefined,
+    over: undefined as string | undefined,
+    last: undefined as Point | undefined,
+  }
+
+  const delay = props.delay ?? 250
+  const max = props.max ?? 4
+  const tolerance = props.tolerance ?? 80
+  const edge = props.edge ?? 18
+
+  const cancel = () => {
+    if (state.timer !== undefined) clearTimeout(state.timer)
+    state.timer = undefined
+    state.pending = undefined
+  }
+
+  const reset = () => {
+    cancel()
+    state.over = undefined
+    state.last = undefined
+    state.locs.length = 0
+  }
+
+  const move = (event: MouseEvent) => {
+    if (!props.enabled()) return
+    const el = props.el()
+    if (!el) return
+
+    const rect = el.getBoundingClientRect()
+    const x = event.clientX
+    const y = event.clientY
+    if (x < rect.left || x > rect.right || y < rect.top || y > rect.bottom) return
+
+    state.locs.push({ x, y })
+    if (state.locs.length > max) state.locs.shift()
+  }
+
+  const wait = () => {
+    if (!props.enabled()) return 0
+    if (!props.active()) return 0
+
+    const el = props.el()
+    if (!el) return 0
+    if (state.locs.length < 2) return 0
+
+    const rect = el.getBoundingClientRect()
+    const loc = state.locs[state.locs.length - 1]
+    if (!loc) return 0
+
+    const prev = state.locs[0] ?? loc
+    if (prev.x < rect.left || prev.x > rect.right || prev.y < rect.top || prev.y > rect.bottom) return 0
+    if (state.last && loc.x === state.last.x && loc.y === state.last.y) return 0
+
+    if (rect.right - loc.x <= edge) {
+      state.last = loc
+      return delay
+    }
+
+    const upper = { x: rect.right, y: rect.top - tolerance }
+    const lower = { x: rect.right, y: rect.bottom + tolerance }
+    const slope = (a: Point, b: Point) => (b.y - a.y) / (b.x - a.x)
+
+    const decreasing = slope(loc, upper)
+    const increasing = slope(loc, lower)
+    const prevDecreasing = slope(prev, upper)
+    const prevIncreasing = slope(prev, lower)
+
+    if (decreasing < prevDecreasing && increasing > prevIncreasing) {
+      state.last = loc
+      return delay
+    }
+
+    state.last = undefined
+    return 0
+  }
+
+  const activate = (id: string) => {
+    cancel()
+    props.onActivate(id)
+  }
+
+  const request = (id: string) => {
+    if (!id) return
+    if (props.active() === id) return
+
+    if (!props.active()) {
+      activate(id)
+      return
+    }
+
+    const ms = wait()
+    if (ms === 0) {
+      activate(id)
+      return
+    }
+
+    cancel()
+    state.pending = id
+    state.timer = window.setTimeout(() => {
+      state.timer = undefined
+      if (state.pending !== id) return
+      state.pending = undefined
+      if (!props.enabled()) return
+      if (!props.active()) return
+      if (state.over !== id) return
+      props.onActivate(id)
+    }, ms)
+  }
+
+  const enter = (id: string, event: MouseEvent) => {
+    if (!props.enabled()) return
+    state.over = id
+    move(event)
+    request(id)
+  }
+
+  const leave = (id: string) => {
+    if (state.over === id) state.over = undefined
+    if (state.pending === id) cancel()
+  }
+
+  return { move, enter, leave, activate, request, cancel, reset }
+}