xamarin/Xamarin.Forms

[Bug] iOS collection view items are misaligned with background

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#8,719 opened on Nov 29, 2019

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a/collectionviewe/2 :clock2:good first issuehelp wantedinactivep/iOS 🍎t/bug :bug:up-for-grabs

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Description

Description

On iOS, it's not possible to align content with the collection view item background, if a background colour is set.

This image for an example of what I mean:

This was produced with this Xaml:

This is only an issue on iOS, not on Android.

I've included a renderer in the iOS solution that hacks a fix in for this. After the fix, the item is displayed correctly:

I believe the issue is caused by the fact that the rendered content is given a bounds with an x of -1 and a y of -1.

Steps to Reproduce

Run the app

Expected Behavior

Background and accent are aligned

Actual Behavior

Background and accent are misaligned

Uncomment out the renderer attribute on iOS to see a hack that works around the bug

Basic Information

  • Version with issue:
  • Last known good version:
  • IDE: Visual Studio for Mac
  • Platform Target Frameworks:
    • iOS: 13.6.0.12
  • Nuget Packages: Xamarin Forms 4.3.0.991211
  • Affected Devices: iOS

Reproduction Link

https://github.com/petermajor/CollectionViewItemAlignmentBug

Contributor guide

Research direction
Investigate the iOS renderer for CollectionView items and check the bounds calculation, particularly the x,y offsets.
Tech stack
csharp
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
Xamarin.FormsiOS development
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55