CollectionView does not adjust the size of a group when items in the group change size in ios and android

[JPfahl]

Description

I am providing the ability to collapse a group in a collectionview. This works perfectly in windows but in ios and android when the height of the items in the group is changed the space in the collectionview for the group is not adjusted. So you endup with a gap the size of the original group.

Steps to Reproduce

In code set the MaximumHeightRequest of each item in a group to 0.

iOS The group may collapse but it will never expand again.

Android

Windows

Link to public reproduction project repository

No response

Version with bug

8.0.20 SR4

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android

Affected platform versions

No response

Did you find any workaround?

No

Relevant log output

No response

[RoiChen001]

Can repro this issue at Android platform on the latest 17.10 Preview 6 (8.0.20&8.0.21), but it won't be reproduced on iOS. If you have any questions about this, please provide us with a sample project to better illustrate the problem.

[JPfahl]

In iOS the group will collapse but it will never expand again.

[JPfahl]

Sample Code:

`<?xml version="1.0" encoding="utf-8" ?> <ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="MauiDev.Views.Sample" Title="Sample">

`

`using System.Collections.ObjectModel; using System.ComponentModel; using System.Runtime.CompilerServices;

namespace MauiDev.Views;

public class Item : INotifyPropertyChanged { public string Name { get; set; }

private double size;
public double Size
{
    get => size;
    set => SetProperty(ref size, value);
}

public event PropertyChangedEventHandler PropertyChanged;

protected virtual bool SetProperty<T>(ref T propertyStorage, T value, [CallerMemberName] string propertyName = null)
{
    bool result = false;

    if (!Equals(propertyStorage, value))
    {
        propertyStorage = value;
        result = true;

        InvokePropertyChanged(propertyName);
    }

    return result;
}

public virtual void InvokePropertyChanged(string propertyName)
{
    PropertyChanged?.Invoke(this,
        new PropertyChangedEventArgs(propertyName));
}

}

public class Group : Collection { public string Name { get; set; } public ICommand Toggle => new Command(parameter => { if (parameter is Group group) { foreach(Item item in group) { if (item.Size == 0) { item.Size = 30; } else { item.Size = 0; } } } }); }

public partial class Sample : ContentPage

{ public System.Collections.ObjectModel.ObservableCollection Groups { get; set; } = [];

public Sample()
{
    InitializeComponent();

    Group group1 = new Group() { Name = "One" };
    group1.Add(new Item() { Name = "A", Size =30 });
    group1.Add(new Item() { Name = "B", Size = 30 });
    group1.Add(new Item() { Name = "C", Size = 30 });
    Groups.Add(group1);
    Group group2 = new Group() { Name = "Two" };
    group2.Add(new Item() { Name = "D", Size = 30 });
    group2.Add(new Item() { Name = "E", Size = 30 });
    group2.Add(new Item() { Name = "F", Size = 30 });
    Groups.Add(group2);
    BindingContext = this;
}

}`

[JPfahl]

I provided a simple example (one page).