fix: toc range calcation

Signed-off-by: Innei <i@innei.in>

src/renderer/src/components/ui/markdown/components/Toc.tsx

@@ -3,10 +3,22 @@ import { getViewport } from "@renderer/atoms/hooks/viewport"
 import { getElementTop } from "@renderer/lib/dom"
 import { springScrollToElement } from "@renderer/lib/scroller"
 import { cn } from "@renderer/lib/utils"
-import { useGetWrappedElementPosition } from "@renderer/providers/wrapped-element-provider"
+import {
+  useGetWrappedElementPosition,
+  useWrappedElementSize,
+} from "@renderer/providers/wrapped-element-provider"
 import { AnimatePresence, m } from "framer-motion"
 import { throttle } from "lodash-es"
-import { memo, useContext, useEffect, useMemo, useRef, useState } from "react"
+import {
+  memo,
+  startTransition,
+  useContext,
+  useEffect,
+  useLayoutEffect,
+  useMemo,
+  useRef,
+  useState,
+} from "react"
 import { useEventCallback } from "usehooks-ts"
 
 import { useScrollViewElement } from "../../scroll-area/hooks"
@@ -93,8 +105,10 @@ export const Toc: Component = ({ className }) => {
     },
   )
 
+  const { h } = useWrappedElementSize()
   const [currentScrollRange, setCurrentScrollRange] = useState([-1, 0])
-  const titleBetweenPositionTopRangeMap = useMemo(() => {
+
+  const headingRangeParser = () => {
     // calculate the range of data-container-top between each two headings
     const titleBetweenPositionTopRangeMap = [] as [number, number][]
     for (let i = 0; i < $headings.length - 1; i++) {
@@ -119,7 +133,16 @@ export const Toc: Component = ({ className }) => {
       titleBetweenPositionTopRangeMap.push([headingTop, nextTop])
     }
     return titleBetweenPositionTopRangeMap
-  }, [$headings])
+  }
+
+  const [titleBetweenPositionTopRangeMap, setTitleBetweenPositionTopRangeMap] =
+    useState(headingRangeParser)
+
+  useLayoutEffect(() => {
+    startTransition(() => {
+      setTitleBetweenPositionTopRangeMap(headingRangeParser)
+    })
+  }, [$headings, h])
 
   const throttleCallerRef = useRef<DebouncedFuncLeading<() => void>>()
   const getWrappedElPos = useGetWrappedElementPosition()
@@ -152,10 +175,11 @@ export const Toc: Component = ({ className }) => {
         setCurrentScrollRange([currentRangeIndex, precent])
       } else {
         const last = titleBetweenPositionTopRangeMap.at(-1) || [0, 0]
-        if (top > last[1]) {
+
+        if (top + winHeight > last[1]) {
           setCurrentScrollRange([
-            titleBetweenPositionTopRangeMap.length - 1,
-            1,
+            titleBetweenPositionTopRangeMap.length,
+            1 - (last[1] - top) / winHeight,
           ])
         } else {
           setCurrentScrollRange([-1, 1])
@@ -168,6 +192,7 @@ export const Toc: Component = ({ className }) => {
 
     return () => {
       scrollContainerElement.removeEventListener("scroll", handler)
+      handler.cancel()
     }
   }, [
     getWrappedElPos,