Suppress rerendering of WindowVirtualizer outside of viewport

inokawa · Mar 5, 2024 · bca7113 · bca7113
1 parent 2b64b26
commit bca7113
Showing 1 changed file with 15 additions and 15 deletions.
diff --git a/src/core/store.ts b/src/core/store.ts
@@ -17,7 +17,7 @@ import type {
  ItemResize,
  ItemsRange,
 } from "./types";
-import { abs, clamp, max, min } from "./utils";
+import { abs, max, min } from "./utils";
 
 // Scroll offset and sizes can have sub-pixel value if window.devicePixelRatio has decimal value
 const SUBPIXEL_THRESHOLD = 1.5; // 0.5 * 3
@@ -173,11 +173,9 @@ export const createVirtualStore = (
  return computeRange(cache, offset, _prevRange[0], viewportSize);
  };
  const getTotalSize = (): number => computeTotalSize(cache);
- const getScrollableSize = (): number =>
- getTotalSize() + startSpacerSize + endSpacerSize;
  const getMaxScrollOffset = (): number =>
  // total size can become smaller than viewport size
- max(0, getScrollableSize() - viewportSize);
+ max(0, getTotalSize() + startSpacerSize - viewportSize);
  const getItemOffset = (index: number): number => {
  return computeStartOffset(cache, index) - pendingJump;
  };
@@ -210,7 +208,7 @@ export const createVirtualStore = (
  return _prevRange;
  }
  _prevRange = getRange(
- scrollOffset - startSpacerSize + pendingJump + jump
+ max(0, scrollOffset - startSpacerSize + pendingJump + jump)
  );
 
  if (_frozenRange) {
@@ -259,7 +257,7 @@ export const createVirtualStore = (
  const flushedIsJumpByShift = isJumpByShift;
  jump = 0;
  isJumpByShift = false;
- if (viewportSize > getScrollableSize()) {
+ if (viewportSize > getTotalSize() + startSpacerSize + endSpacerSize) {
  // In this case applying jump will not cause scroll.
  // Current logic expects scroll event occurs after applying jump so discard it.
  return [0, false];
@@ -281,16 +279,10 @@ export const createVirtualStore = (
 
  switch (type) {
  case ACTION_SCROLL: {
- // Scroll offset may exceed min or max especially in Safari's elastic scrolling.
- const nextScrollOffset = clamp(payload, 0, getMaxScrollOffset());
  const flushedJump = _flushedJump;
  _flushedJump = 0;
- // Skip if offset is not changed
- if (nextScrollOffset === scrollOffset) {
- break;
- }
 
- const delta = nextScrollOffset - scrollOffset;
+ const delta = payload - scrollOffset;
  const distance = abs(delta);
 
  // Scroll event after jump compensation is not reliable because it may result in the opposite direction.
@@ -327,8 +319,16 @@ export const createVirtualStore = (
  // Update synchronously if scrolled a lot
  shouldSync = distance > viewportSize;
 
- scrollOffset = nextScrollOffset;
- mutated = UPDATE_VIRTUAL_STATE + UPDATE_SCROLL_EVENT;
+ scrollOffset = payload;
+ mutated = UPDATE_SCROLL_EVENT;
+ // Skip if offset is not changed
+ // Scroll offset may exceed min or max especially in Safari's elastic scrolling.
+ if (
+ scrollOffset >= startSpacerSize &&
+ scrollOffset <= getMaxScrollOffset()
+ ) {
+ mutated += UPDATE_VIRTUAL_STATE;
+ }
  break;
  }
  case ACTION_SCROLL_END: {