From 762c86e09419299b68b194b93eb272d3b20628c7 Mon Sep 17 00:00:00 2001
From: Danila Poyarkov <dev@dannote.net>
Date: Sat, 23 May 2026 01:17:48 +0300
Subject: [PATCH] Revert "perf(canvas): defer backing rebuilds while zooming"

This reverts commit 21a79d4cd562ae61e5aaeb0083e482e55bc21a7b.
---
 .../src/canvas/renderer/retained-backing.ts   | 43 ++++++-------------
 .../render/canvas/retained-backing.test.ts    | 34 ---------------
 2 files changed, 12 insertions(+), 65 deletions(-)

diff --git a/packages/core/src/canvas/renderer/retained-backing.ts b/packages/core/src/canvas/renderer/retained-backing.ts
index 4f1d7970e..3d25bfe82 100644
--- a/packages/core/src/canvas/renderer/retained-backing.ts
+++ b/packages/core/src/canvas/renderer/retained-backing.ts
@@ -45,7 +45,10 @@ export function updateSceneBackingPreviewState(r: SkiaRenderer, layer: RenderLay
   if (layer !== 'scene') return
   const previous = r.lastSceneViewport
   const viewportChanged =
-    !previous || previous.panX !== r.panX || previous.panY !== r.panY || previous.zoom !== r.zoom
+    !previous ||
+    previous.panX !== r.panX ||
+    previous.panY !== r.panY ||
+    previous.zoom !== r.zoom
   if (viewportChanged) {
     const timestamp = now()
     if (r.sceneBackingLastViewportEventAt > 0) {
@@ -76,31 +79,13 @@ function backingMetadataMatches(
   )
 }
 
-function scenePictureMetadataMatches(
-  r: SkiaRenderer,
-  sceneVersion: number,
-  positionPreviewVersion: number
-): boolean {
-  return !!(
-    r.scenePicture &&
-    r.scenePicturePageId === r.pageId &&
-    r.scenePictureVersion === sceneVersion &&
-    r.scenePicturePositionPreviewVersion === positionPreviewVersion
-  )
-}
-
 function backingScreenCoverageContainsViewport(r: SkiaRenderer): boolean {
   const backing = r.sceneBacking
   if (!backing) return false
   const scale = r.zoom / backing.zoom
   const x = r.panX - backing.panX * scale
   const y = r.panY - backing.panY * scale
-  return (
-    x <= 0 &&
-    y <= 0 &&
-    x + backing.width * scale >= r.viewportWidth &&
-    y + backing.height * scale >= r.viewportHeight
-  )
+  return x <= 0 && y <= 0 && x + backing.width * scale >= r.viewportWidth && y + backing.height * scale >= r.viewportHeight
 }
 
 function backingWorldCoverageContainsLiveViewport(r: SkiaRenderer): boolean {
@@ -144,7 +129,12 @@ function drawSceneBacking(
   const backing = r.sceneBacking
   if (
     !backing ||
-    !backingCoverageContainsLiveViewport(r, sceneVersion, allowStaleZoom, positionPreviewVersion)
+    !backingCoverageContainsLiveViewport(
+      r,
+      sceneVersion,
+      allowStaleZoom,
+      positionPreviewVersion
+    )
   ) {
     return false
   }
@@ -449,16 +439,6 @@ export function renderSceneBacking(
     positionPreviewVersion
   )
   if (!hasCoverage) {
-    const canDeferBackingRecordDuringViewportPreview =
-      allowStaleZoom &&
-      backingMetadataMatches(r, sceneVersion, positionPreviewVersion) &&
-      scenePictureMetadataMatches(r, sceneVersion, positionPreviewVersion)
-    if (canDeferBackingRecordDuringViewportPreview) {
-      cancelSceneBackingBuild(r)
-      r.sceneBackingNeedsCrispRender = true
-      return false
-    }
-
     if (
       !r.sceneBacking ||
       !backingMetadataMatches(r, sceneVersion, positionPreviewVersion) ||
@@ -484,3 +464,4 @@ export function renderSceneBacking(
     positionPreviewVersion
   )
 }
+
diff --git a/tests/engine/render/canvas/retained-backing.test.ts b/tests/engine/render/canvas/retained-backing.test.ts
index 5f1194d50..7a6a44606 100644
--- a/tests/engine/render/canvas/retained-backing.test.ts
+++ b/tests/engine/render/canvas/retained-backing.test.ts
@@ -1,5 +1,4 @@
 import { expect, mock, test } from 'bun:test'
-
 import type { Canvas, Image as CKImage, Surface } from 'canvaskit-wasm'
 
 import type { SkiaRenderer } from '#core/canvas/renderer'
@@ -148,39 +147,6 @@ test('retained scene backing allows same-zoom previews while panning', () => {
   expect(canvas.drawImageRectOptions).toHaveBeenCalled()
 })
 
-test('retained scene backing defers coverage-miss rebuilds during active viewport previews', () => {
-  const r = createRenderer(() => null)
-  r.zoom = 0.5
-  r.sceneBackingPreviewUntil = Number.POSITIVE_INFINITY
-  r.scenePicture = {} as SkiaRenderer['scenePicture']
-  r.scenePictureVersion = 1
-  r.scenePicturePositionPreviewVersion = 0
-  r.scenePicturePageId = 'page'
-  r.sceneBacking = {
-    image: { delete: mock() } as CKImage,
-    pageId: 'page',
-    sceneVersion: 1,
-    positionPreviewVersion: 0,
-    panX: 0,
-    panY: 0,
-    zoom: 1,
-    width: 100,
-    height: 100,
-    dpr: 1,
-    worldX: 0,
-    worldY: 0,
-    worldWidth: 100,
-    worldHeight: 100
-  } as NonNullable<SkiaRenderer['sceneBacking']>
-  const canvas = createCanvas()
-  const graph = createGraph()
-
-  expect(renderSceneBacking(r, canvas, graph, 1)).toBe(false)
-  expect(r.surface.makeSurface).not.toHaveBeenCalled()
-  expect(canvas.drawImageRectOptions).not.toHaveBeenCalled()
-  expect(r.sceneBackingNeedsCrispRender).toBe(true)
-})
-
 test('retained scene backing invalidates stale position-preview metadata', () => {
   const r = createRenderer(() => null)
   r.sceneBacking = {