fix: 修复长文档分页与滚动同步

2026-07-26 08:43:56 +08:00
parent 1d93f31f85
commit d62552384f
15 changed files with 449 additions and 61 deletions
@@ -0,0 +1,34 @@
+export interface PageVerticalRange {
+  top: number;
+  bottom: number;
+}
+
+export const PREVIEW_SCROLLBAR_WIDTH_PX = 14;
+
+export function getNearestPageNumber(
+  viewportCenter: number,
+  pages: readonly PageVerticalRange[]
+) {
+  if (pages.length === 0 || !Number.isFinite(viewportCenter)) {
+    return 0;
+  }
+
+  let nearestPage = 1;
+  let nearestDistance = Number.POSITIVE_INFINITY;
+
+  for (const [index, page] of pages.entries()) {
+    const distance =
+      viewportCenter < page.top
+        ? page.top - viewportCenter
+        : viewportCenter > page.bottom
+          ? viewportCenter - page.bottom
+          : 0;
+
+    if (distance < nearestDistance) {
+      nearestPage = index + 1;
+      nearestDistance = distance;
+    }
+  }
+
+  return nearestPage;
+}