fix: Affix shake when switching from hide to show

[madocto]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
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• TypeScript definition update
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🔗 Related issue link

fix: #37970

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Affix shake when switching from hide to show.
🇨🇳 Chinese	修复当 Affix 隐藏切换到显示时会出现抖动。

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[github-actions]

[madocto]

let affixInstance: InternalAffixClass | null = null;
render(
  <AffixMounter
    getInstance={inst => {
      affixInstance = inst;
    }}
    offsetBottom={0}
  />,
);

await waitFakeTimer();
await movePlaceholder(300);

console.log(affixInstance!.state.affixStyle); // { position: 'fixed', bottom: 668, width: undefined, height: undefined }

hi，我想写一个测试用例，想对比滚动前后 affixStyle 的变化，但是发现 width 和 height 都是 undefined，能指导下我吗？

[afc163]

jsdom 里元素尺寸和位置都是 0，需要对相关 dom 操作方法做 mock：https://github.com/ant-design/ant-design/blob/master/components/affix/__tests__/Affix.test.tsx#L75-L81

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (516e2ff) compared to base (53c2be0).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##            master    #38410   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          446       446           
  Lines         8304      8310    +6     
  Branches      2526      2528    +2     
=========================================
+ Hits          8304      8310    +6     

Impacted Files	Coverage Δ
components/affix/index.tsx	100.00% <100.00%> (ø)
components/table/util.ts	100.00% <0.00%> (ø)
components/_util/ActionButton.tsx	100.00% <0.00%> (ø)
components/alert/ErrorBoundary.tsx	100.00% <0.00%> (ø)
components/table/hooks/useSorter.tsx	100.00% <0.00%> (ø)
components/upload/UploadList/ListItem.tsx	100.00% <0.00%> (ø)
...date-picker/generatePicker/generateRangePicker.tsx	100.00% <0.00%> (ø)
...ate-picker/generatePicker/generateSinglePicker.tsx	100.00% <0.00%> (ø)

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[afc163]

[madocto]

done