CollectionView VisualStateManager can't change selection color

Question

I am trying to customize the selection color of a cell in a CollectionView but no matter how I try it, it's always an ugly grey.

I want my item template to have rounded corners, but when I select an item the I see ugly square grey corners behind it, as in this image:

Here's my current XAML:

<?xml version="1.0" encoding="UTF-8"?>
<ContentView
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="Tests.CollectionViewTest">
<ContentView.Content>
    <CollectionView
        x:Name="collectionView"
        Margin="15,0"
        ItemSizingStrategy="MeasureFirstItem"
        Grid.Row="1"
        Grid.RowSpan="2"
        VerticalScrollBarVisibility="Never"
        BackgroundColor="Transparent"
        SelectionMode="Multiple"
        HorizontalOptions="Center"
        VerticalOptions="Center"
        >

        <CollectionView.ItemsLayout>
            <GridItemsLayout
                Orientation="Vertical"
                HorizontalItemSpacing="1"
                VerticalItemSpacing="1"
                Span="3" />
        </CollectionView.ItemsLayout>
        <CollectionView.ItemTemplate>
            <DataTemplate>
                <Frame
                    x:Name="selectionFrame"
                    CornerRadius="18"
                    BackgroundColor="Transparent"
                    Padding="0"
                    HasShadow="False"
                    IsClippedToBounds="True"
                    BorderColor="Transparent">
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup
                            Name="CommonStates">
                            <VisualState
                                Name="Normal" />
                            <VisualState
                                Name="Focused">
                                <VisualState.Setters>
                                    <Setter
                                        Property="BackgroundColor"
                                        Value="Transparent" />
                                </VisualState.Setters>
                            </VisualState>
                            <VisualState
                                Name="Selected">
                                <VisualState.Setters>
                                    <Setter
                                        Property="BackgroundColor"
                                        Value="#e25fc4" />
                                </VisualState.Setters>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <StackLayout
                        BackgroundColor="#f7f0f6"
                        HorizontalOptions="FillAndExpand"
                        VerticalOptions="FillAndExpand"
                        Orientation="Vertical"
                        Padding="8,0,8,10"
                        Margin="10"
                        Spacing="0"
                        HeightRequest="100">
                        <Label
                            Padding="10"
                            x:Name="ServiceName"
                            BackgroundColor="Transparent"
                            Text="Some Text"
                            HorizontalTextAlignment="Center"
                            TextColor="HotPink"
                            FontSize="Micro"
                            FontAttributes="Bold"
                            HorizontalOptions="Center"
                            VerticalOptions="End" />
                        <Label
                            BackgroundColor="Transparent"
                            Text="Some More Text"
                            HorizontalTextAlignment="Center"
                            TextColor="HotPink"
                            FontSize="Micro"
                            HorizontalOptions="Center"
                            VerticalOptions="Start" />
                    </StackLayout>
                </Frame>
            </DataTemplate>
        </CollectionView.ItemTemplate>
    </CollectionView>
</ContentView.Content>
</ContentView>

And my code-behind:

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using Xamarin.Forms;

namespace Tests
{
    public partial class CollectionViewTest : ContentView
    {
        public CollectionViewTest()
        {
            InitializeComponent();
            collectionView.ItemsSource = new ObservableCollection<string>()
            {
                "", "", "", "", "", "", "", "", "", "", "", "", "", ""
            };
        }
    }
}

I've tried other ways of doing this too, but nothing worked.

Is there a way to do it, or is this just a bug with CollectionView?

Answer 1

I found a kludgey solution, and in the absence of one that works the right way, it will have to do.

1. Set selection behavior in the CollectionView to none.
2. Put a tapGestureRecognizer into the itemTemplate
3. To simulate selection states, in the event handler for the tapGestureRecognizer, cast the sender to a Frame (or whatever element you attached the gesture recognizer to) and turn the frame border on or off (or do whatever you need to for your own custom selected-state appearance).
4. Manually handle whatever would normally be triggered by the CollectionView in response to selections. In other words, if you can select multiple items, you might be tracking the selected items in a separate list, and you will now have to do that from inside the tapGestureRecognizer.

It’s wrong but it works and sometimes that’s how you gotta do.

Answer 2

I start again to try to make it work, now i have a Frame in a StackLayout. And not a the other way around. But no luck is see , now there are no corners around the selected item.Sorry but i cannot make it to work.