bug(MatCheckbox): Tooltip not shown on keyboard navigation
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- TypeScript
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説明
### Is this a regression?
- [X] Yes, this behavior used to work in the previous version
### The previous version in which this bug was not present was
14
### Description
Hi, after upgrading to Angular v15 tooltips are no longer displayed when navigating to a checkbox element via keyboard.
I added a [repro link on stackblitz ](https://stackblitz.com/edit/hvjxck?file=src%2Fapp%2Fradio-overview-example.html)which has a radio button and a checkbox. You can see that when navigating to the radio button via keyboard the tooltip is shown, but when doing the same to the checkbox, nothing is displayed.
I looked over the tooltip code where the [events are being monitored](https://github.com/angular/components/blob/15.2.x/src/material/tooltip/tooltip.ts#L376-L387). This fires on the keyboard focus event for the radio, but not for the checkbox.
We can see that the second parameter of the `monitor` method is left default, which is `false`, this means that it will not check if an event was fired on a children. For radio buttons and checkboxes the event (focus) is fired on a children, on the input. So it is strange that for the radio button this works.
Looking into the FocusMonitor code, I saw that on the focus event (`_onFocus`), [elementInfo](https://github.com/angular/components/blob/15.2.x/src/cdk/a11y/focus-monitor/focus-monitor.ts#L425) came with `checkChildren` on `true` for the radio, but on `false` for the checkbox. Now, on the tooltip code, all the monitors have the default value for `checkChildren` which is false.
I looked after this in the radio code and saw that the `monitor` is [called with checkChildren on true](https://github.com/angular/components/blob/15.2.x/src/material/radio/radio.ts#L561). So this is why the tooltip fires on the radio.
But the tooltip did fire on the checkbox in v14 too; not anymore now in the new MDC checkbox, there is no monitor called with `checkChildren` on `true`. If you open the legacy checkbox code, you can see that it was, so that is why it worked before.
So this worked before and still works using the same mechanism for other elements (like radio, but probably others too), but seems like a strange way, since the tooltip doesn't fire because of the monitor inside the tooltip directive, but a custom monitor inside the respective components.
Could the tooltip monitor all the elements using `checkChildren` on `true` or do you think it could cause issues?
Tested this on v15, but probably is the same for v16 and v17.
### Reproduction
StackBlitz link: https://stackblitz.com/edit/hvjxck?file=src%2Fapp%2Fradio-overview-example.html
Steps to reproduce:
1. Navigate to the checkbox via tab key
2. Observe that the tooltip is not shown
### Expected Behavior
Tooltip is visible when navigating via keyboard on checkboxes.
### Actual Behavior
Tooltip is not visible when navigating via keyboard on checkboxes.
### Environment
- Angular: 15.2.9
- CDK/Material: 15.2.9
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): macOS
コントリビューションガイド
調査の方向性
リンク先の StackBlitz にあるキーボードナビゲーションのケースを再現し、その後、言及されているモニターおよびフォーカス処理の行の周辺にある src/material/tooltip/tooltip.ts と src/cdk/a11y/focus-monitor/focus-monitor.ts を読みます。src/material/radio/radio.ts のモニター呼び出しを、MDC checkbox と legacy checkbox の実装と比較します。キーボードでフォーカスされた checkbox にツールチップが表示され、radio の動作にリグレッションが発生しなければ完了です。
索引モデルが issue の本文から書いたものです。
評価
- 技術スタック
- angular, typescript
- 領域
- accessibility, frontend
- issue の種類
- バグ
- 難易度
- 3/5
- 見積もり時間
- 1〜2日
- 活発さ
- 停滞
- 明瞭さ
- おおむね明確
- 初心者へのやさしさ
- 47/100