Hacktoberfest 2026: as issues que os mantenedores marcaram para outubro, abertas e boas para iniciantes. Ver issues do Hacktoberfest

[iOS][Fabric] Pinch-zoomed ScrollView breaks (position jumps, cannot zoom back out) after its size changes

Aberta
  • Algo errado?
#58,499 0 comentários 0 reações 0 responsáveis Ver no GitHub

Mantenedores costumam responder em até 1 dia

Ninguém assumiu esta issue ainda.

Avaliação

Dificuldade
3/5
Tempo estimado
1-2 dias
Facilidade para iniciantes
25/100
Tipo de issue
Bug
Clareza
Claramente especificada
Status de atividade
Estagnada
Stack de tecnologia
ios, objective-c, react-native
Domínio
mobile

Direção de pesquisa

Comece com updateState:oldState: e prepareForRecycle de RCTScrollViewComponentView e, em seguida, execute o exemplo reproducer-react-native no iOS. Verifique o comportamento durante o zoom e ao redimensionar ou girar; está concluído quando a posição de rolagem permanece estável e o conteúdo pode voltar a ser totalmente reduzido após as alterações de tamanho.

Escrita pelo modelo de indexação a partir do texto da issue.

Descrição

Component: ScrollView Needs: Triage :mag: Platform: iOS
Description

On iOS with the new architecture, a ScrollView with maximumZoomScale > 1 gets into a broken state whenever its size changes while the user is zoomed in (device rotation, or the layout around it changing):

  1. The scrolled position jumps to a different spot.
  2. The content can no longer be zoomed all the way back out; it stays stuck against one side or corner.

The only way to recover is to zoom all the way out in the broken state and then resize again (rotate back and forth). After that it works again until the next resize while zoomed.

Cause. RCTScrollViewComponentView returns _containerView from viewForZoomingInScrollView:, so while zoomed in that view carries UIScrollView's scale transform. In updateState:oldState: a content size change does

_containerView.frame = CGRect{RCTCGPointFromPoint(data.contentBoundingRect.origin), contentSize};
...
self->_scrollView.contentSize = contentSize;
  • Setting frame on a view whose transform is not the identity is undefined behavior per the UIView docs ("If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored"). In practice UIKit shrinks the container's bounds by the zoom scale, so when the user zooms back out to scale 1 the content is smaller than the scroll view and sits in a corner.
  • contentSize is set to the unzoomed size while zoomScale != 1. UIScrollView itself keeps contentSize at the zoomed size, so the offset is clamped to the wrong range and the position jumps.

The same code is on main today. prepareForRecycle already hints at it: "Invalidate cached content size so that updateState: recalculates the container frame after zoomScale reset (which may have mutated it in RTL)".

Fix: lay the container out through bounds/center and give the scroll view the zoomed content size. PR: https://github.com/react/react-native/pull/58498

Steps to reproduce
  1. Run the reproducer on an iOS device or simulator (new architecture is on by default).
  2. Pinch to zoom in (2x or more) and pan somewhere away from the top-left.
  3. Tap "Resize" (changes the ScrollView's height) or rotate the device.
  4. The position jumps. Pinch back out: the content stays stuck in a corner and does not fill the ScrollView.
  5. Zoom out fully, resize again: it recovers.
React Native Version

0.87.1

Affected Platforms

Runtime - iOS

Output of npx @react-native-community/cli info
Not run: the reproducer repository is a fresh `reproducer-react-native` template pinned to react-native 0.87.1, run on iOS 18 simulator/device.
Stacktrace or Logs
No crash or log output; the bug is visual.
MANDATORY Reproducer

https://github.com/mifi/reproducer-react-native

Screenshots and Videos

None yet.

Linguagem predominante
C++
Estrelas
127k
Forks
25.3k
Nenhum PR com merge em 30d

Preparar o ambiente

Primeiros passos

  1. Leia a issue inteira e depois o guia de contribuição do projeto.
  2. Comente na issue dizendo que vai assumir — evita que duas pessoas façam o mesmo trabalho.
  3. Faça um fork do repositório e trabalhe em uma branch.
  4. Abra um pull request que referencie o número da issue.

Mais de react/react-native

Todas as issues de react/react-native

Issues semelhantes

Mais issues de C++

Receba novas issues na sua caixa de entrada

Um resumo curto de issues do GitHub para quem está começando.