react / react/react-native

<View /> doesn't recalculate it's size when a descendant <Text /> changes height due to wrapping following a device rotation

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描述

🐛 Bug Report

I believe I've found a bug in the View size calculation logic in React Native. In certain cases, the ancestor View fails to recalculate its size if a descendant <Text /> component changes in size due to a rotation and subsequent text (re)wrapping.

The following shows three states: initial, rotated, and back to original orientation. Notice that the fuschia view "grows" after returning to the original orientation.

Initial orientation
image
Portrait
image
Back to initial orientation
image

Speculative Analysis and Workaround

This appears to be an issue where an ancestor view caches a layout calculation and doesn't trigger a re-calculation when a nested Text component changes in size due to orientation changes.

After some playing around, we've figured out that if you "poke" any of the style properties that affect the view's style layout, the view will recalculate and be correct. We did this by toggling a state var upon rotation and then adding/removing a style object to the view's styles array that contained an extra paddingBottom that mirrored the existing padding on the view (basically we changed the style but the effect had no changes to the layout).

You can see a demo of the workaround by uncommenting the line of code below the FIXME comment in the code sample.

To Reproduce

See the code, but basically if you have a <ScrollView> that contains a container <View> which contains another <View> and then have a <Text> element inside that view... this layout bug will happen. I haven't been able to reduce this example further than that.

Expected Behavior

After rotating and going back to the initial orientation, the View should be exactly the same size.

Code Example

Github repo: https://github.com/jeremywiebe/react-native-text-orientation-bug

Environment

  React Native Environment Info:
    System:
      OS: macOS 10.14.2
      CPU: (8) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
      Memory: 34.97 MB / 16.00 GB
      Shell: 3.0.0 - /usr/local/bin/fish
    Binaries:
      Node: 8.15.0 - /usr/local/bin/node
      Yarn: 1.13.0 - /usr/local/bin/yarn
      npm: 6.4.1 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
      Android SDK:
        API Levels: 23, 25, 27
        Build Tools: 23.0.1, 25.0.0, 25.0.2, 25.0.3, 27.0.3, 28.0.1, 28.0.2, 28.0.3
        System Images: android-16 | Intel x86 Atom, android-16 | Google APIs Intel x86 Atom, android-19 | Intel x86 Atom, android-19 | Google APIs Intel x86 Atom, android-23 | Google APIs Intel x86 Atom_64, android-24 | Google APIs Intel x86 Atom, android-24 | Google Play Intel x86 Atom, android-25 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom
    IDEs:
      Android Studio: 3.1 AI-173.4907809
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.6.3 => 16.6.3 
      react-native: 0.58.4 => 0.58.4 

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  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

调研方向

从链接的复现仓库开始,复现涉及 ScrollView、嵌套的 View 组件以及 Text 换行的旋转序列。阅读报告中描述的 View 大小计算逻辑,并比较初始、竖屏和恢复后的方向。完成的标准是:祖先 View 在不使用样式更改 workaround 的情况下恢复到完全相同的大小。

由索引模型根据 Issue 内容生成。

评估

技术栈
react-native
领域
mobile-dev
Issue 类型
缺陷
难度
4/5
预计耗时
3-5 天
活跃度
停滞
描述清晰度
基本清楚
新手友好度
35/100

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