upd: optimize sync scroll

src/renderer/components/Preview.vue

@@ -231,13 +231,14 @@ export default defineComponent({
       }
     }
 
-    function revealLine (startLine: number, endLine?: number) {
+    function revealLine (startLine: number) {
       if (startLine <= 1) {
         scrollTopTo(0)
         return
       }
 
       const nodes = refViewWrapper.value!.querySelectorAll<HTMLElement>(`.markdown-body [${DOM_ATTR_NAME.SOURCE_LINE_START}]`)
+      let prevEl: HTMLElement | undefined
       for (let i = 0; i < nodes.length; i++) {
         const el = nodes[i]
 
@@ -250,10 +251,31 @@ export default defineComponent({
         }
 
         const lineNumber = parseInt(el.dataset.sourceLine || '0')
-        if (lineNumber >= startLine && lineNumber <= (endLine || Number.MAX_SAFE_INTEGER)) {
+
+        if (lineNumber < startLine) {
+          if (i === nodes.length - 1) {
+            refViewWrapper.value!.scrollTop = refViewWrapper.value!.scrollHeight - refViewWrapper.value!.clientHeight
+            break
+          }
+
+          prevEl = el
+          continue
+        }
+
+        if (lineNumber === startLine) {
           el.scrollIntoView()
           break
         }
+
+        if (prevEl) {
+          const wrapperOffset = refViewWrapper.value!.scrollTop - refViewWrapper.value!.getBoundingClientRect().top
+          const prevOffset = wrapperOffset + prevEl.getBoundingClientRect().top
+          const elOffset = wrapperOffset + el.getBoundingClientRect().top
+          const prevLine = parseInt(prevEl.dataset.sourceLine || '0')
+          const top = Math.round((elOffset * (startLine - prevLine) + prevOffset * (lineNumber - startLine)) / (lineNumber - prevLine))
+          refViewWrapper.value!.scrollTop = top
+          break
+        }
       }
     }
 

src/renderer/plugins/sync-scroll.ts

@@ -41,12 +41,11 @@ export default {
       const savePosition = debounce(saveScrollPosition, 500)
       editor.onDidScrollChange(() => {
         const visibleRange = editor.getVisibleRanges()[0]
-        const startLine = Math.max(1, visibleRange.startLineNumber - 2)
-        const endLine = Math.max(startLine, visibleRange.endLineNumber)
+        const startLine = Math.max(1, visibleRange.startLineNumber - 1)
 
         const top = editor.getScrollTop()
         if (ctx.view.getEnableSyncScroll()) {
-          ctx.view.revealLine(startLine, startLine + (endLine - startLine) / 2)
+          ctx.view.revealLine(startLine)
         }
         savePosition({ editor: top })
       })

src/renderer/services/view.ts

@@ -57,10 +57,9 @@ export async function refresh () {
 /**
  * Reveal line.
  * @param startLine
- * @param endLine
  */
-export function revealLine (startLine: number, endLine?: number) {
-  getActionHandler('view.reveal-line')(startLine, endLine)
+export function revealLine (startLine: number) {
+  getActionHandler('view.reveal-line')(startLine)
 }
 
 /**

src/renderer/types.ts

@@ -116,7 +116,7 @@ export type BuildInActions = {
   'view.render-immediately': () => void,
   'view.render': () => void,
   'view.refresh': () => void,
-  'view.reveal-line': (startLine: number, endLine?: number) => void,
+  'view.reveal-line': (startLine: number) => void,
   'view.scroll-top-to': (top: number) => void,
   'view.get-content-html': () => string,
   'view.get-view-dom': () => HTMLElement | null,