bug(material/autocomplete): Intermittent Scrolling Issue with mat-autocomplete on Mobile Devices

[javamaniac]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

We are experiencing an intermittent but recurring issue with the mat-autocomplete component when accessed via mobile devices. Specifically, when users attempt to scroll through the options presented in the autocomplete dropdown, the scroll action unexpectedly affects the underlying webpage instead of the dropdown list. This behavior disrupts the user's ability to select an option from the autocomplete list and significantly impacts the usability of the component. The issue has been consistently observed across a variety of devices and web browsers, indicating a broader compatibility or event handling problem within the component.

Video Demonstration of the Issue:
https://javamaniac.github.io/angular-autocomplete-example/screen-20240212-143204.mp4

Reproduction

StackBlitz link: https://stackblitz.com/~/github.com/javamaniac/angular-autocomplete-example

The issue with mat-autocomplete scrolling is intermittent and does not have a consistent reproduction sequence. However, it generally involves interactions with the autocomplete component on a mobile device. Below are steps that have sometimes led to the issue, though it may require repeating certain actions or experimenting with the sequence to observe the problem.

Potential Reproduction Sequences:

Basic Interaction:

1. Open the autocomplete dropdown.
2. Attempt to scroll through the options.

Extended Interaction:

1. Open the autocomplete dropdown.
2. Select any option from the list.
3. Clear the selected option (erase the choice).
4. Attempt to scroll through the options again.

External Interaction:

1. Open the autocomplete dropdown.
2. Click outside the dropdown to close it.
3. Re-open the dropdown.
4. Attempt to scroll through the options.

Note: The issue may not manifest on the first attempt and could require varying the sequence of actions, such as selecting and clearing choices multiple times or opening and closing the dropdown before scrolling attempts are made. The problem appears to be more likely to occur after interacting with the dropdown in some way (selecting options, erasing choices, or clicking outside the dropdown) before attempting to scroll through the options again.

Expected Behavior

Dragging (scrolling) within the mat-autocomplete dropdown should scroll through the autocomplete options.

Actual Behavior

Attempting to scroll through the autocomplete options results in the page itself scrolling.

Environment

• Angular: 16, 17 (issue likely affects older versions as well)
• CDK/Material: 16, 17
• Browser(s): Chrome, Edge, Safari
• Operating System (e.g. Windows, macOS, Ubuntu): Android, iOS

Devices tested:

• Google Pixel 6 (Chrome, Edge)
• iPhone SE (Chrome, Safari)

[richardsengers]

This is a real problem, since users are unable to select the right options. This only happens on mobile devices,.

[richardsengers]

It looks like it happens when the keyboard from the device comes into view... when the keyboard is gone, I'm able to scroll

[richardsengers]

A temp fix for this issue, add interactive-widget to resizes-content in the meta tag

More info:
https://github.com/bramus/viewport-resize-behavior/blob/main/explainer.md#proposal
https://developer.mozilla.org/en-US/docs/Web/HTML/Viewport_meta_tag