fix(all): ripple effect is no longer added when scrolling

[liamdebeasi]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
  • Some docs updates need to be made in the ionic-docs repo, in a separate PR. See the contributing guide for details.
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Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue URL: resolves #22030

The tap click utility in Ionic ensures that the active state is added to interactives on iOS and Android. On iOS this is an active shade color. On Android this is the ripple effect.

To align with native, the active state should never be added when scrolling. For example, if you begin to scroll by tapping on a button, that button should not receive the ripple effect. See the below example on Android 12:

demo.mp4

Observe that the ripple effect does not appear on items as the user scrolls. However, when tapping/pressing an item when not scrolling shows the ripple effect.

---

In Ionic, this used to work by listening for the scroll event on ion-content. However, this behavior unintentionally changed in fd1b44a. The downside of this approach is that it adds quite a bit of main thread work due to the scroll listener.

How this all comes together is on touchstart, we create a setTimeout (https://github.com/ionic-team/ionic-framework/blob/main/core/src/utils/tap-click.ts#L103) which, when fired, will add the activated state. When we detect scrolling, the cancelActive function is invoked (https://github.com/ionic-team/ionic-framework/blob/main/core/src/utils/tap-click.ts#L151) which cancels the setTimeout.

What is the new behavior?

• This PR re-introduces the tap click scrolling fix by utilizing the pointercancel event. This event is dispatched when the pointer is used to pan, zoom, or scroll (among other things): https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/pointercancel_event
  When tap click was originally built, the PointerEvents API was not supported in all of the browsers Ionic supports. That is no longer true today: https://caniuse.com/mdn-api_pointerevent

When we begin to scroll, the pointercancel event is fired which then calls cancelActive which prevents the active state from being added.

See a demo below:

	main	branch
md	branch.mp4	fix.mp4
ios	current-ios.mp4	fix-ios.mp4

---

There is another bug on Android that this change fixes. Currently, when you swipe on an interactive (but don't scroll), the ripple effect is added to the element. However, the browser never dispatches the click event, so it looks like you selected the element and nothing happened. With pointercancel, this no longer happens.

See a demo below

main	branch
header-now.mp4	header-fix.mp4

Note: Safari does not dispatch pointercancel in this scenario. However, this bug existed even when we were using the old scroll events method so I am not sure it's worth fixing at the moment.

Does this introduce a breaking change?

• Yes
• No

Other information

[liamdebeasi]

A few things:

1. Let me know if you'd prefer a meeting to review this. I scheduled an architectural alignment meeting for next week so we can discuss tapclick.
2. Any thoughts on how to automate a test for this? Since the activated state is added asynchronously, it's a bit hard to ensure that the ion-activated class is not added without it being flaky.

[sean-perkins]

🚀 thanks for the walkthrough!