badoo/Chatto

Visual bugs when changing many item's heights

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#614 opened on Oct 2, 2019

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Description

When updating heights of multiple items (18 items in my example), I've got a visual bug - flickering effect with new (updated) items are flowing up from the bottom of collection and moving to some top position beyond the screen. I attached video when you can see it if you will look frame-by-frame. I also attached a screenshot of the middle state of this animation.

Video: Screen Recording 2019-10-02 at 18.08.22.mov.zip

Contributor guide

Research direction
Investigate the UICollectionView layout invalidation and animation when updating item heights. Look into the chatto framework's layout implementation to understand how height changes are animated and identify the cause of the flickering.
Tech stack
swift
Domain
mobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
SwiftiOS developmentUICollectionView
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50