fix: auto scrolling to bottom

[urmauur]

Describe Your Changes

1. Imports Adjustments:

   • useCallback is added to the existing imports from React.

2. New Refs Introduced:

   • prevScrollTop: Added as a useRef to track the previous scroll position.
   • isUserManuallyScrollingUp: Added as a useRef to flag when the user manually scrolls up.

3. Effect Logic Update:

   • An additional condition is added in the useEffect to return early if the user is manually scrolling up or if parentRef.current is not defined.

4. Virtualizer Adjustment Function:

   • An early return is added in the shouldAdjustScrollPositionOnItemSizeChange function to avoid adjustments if the user manually scrolls up.

5. New Scroll Handler:

   • A handleScroll function is defined using useCallback. It detects manual user scrolling by comparing the current scroll position with the previous one.
   • The function also checks if the scroll position reaches the bottom, resetting the manual scrolling flag accordingly.
   • Scroll event handling is added to prevent the default/propagation when manual scrolling is detected, updating prevScrollTop.

6. DOM Changes:

   • The onScroll event listener is added to a div element referring to handleScroll.

These changes collectively add functionality to detect and handle user-initiated upward scrolling differently, enhancing the control over virtualized list interactions.

Fixes Issues

Screen.Recording.2024-12-10.at.11.26.48.mov

• Closes bug: If I scroll up it keeps autoscrolling so I have to fight with it or wait for it to finish #4253
• Closes #

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed

[github-actions]

Barecheck - Code coverage report

Total: 68.58%

Your code coverage diff: -0.23% ▾

Uncovered files and lines

File	Lines
web/screens/Thread/ThreadCenterPanel/ChatBody/index.tsx	20-21, 23-24, 26, 30-31, 34-35, 37, 39, 43, 60-62, 64-65, 70, 72-73, 76-78, 80-81, 91, 93, 98-99, 105-106, 108-109, 111-113, 115-116, 120-122, 124, 159

[louis-jan]

Thank you

[github-actions]

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