How can I make it so a HeightRequest inside a template is ignored if not specified in the XAML that uses the template?

user_1422604 0
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This template takes as a binding parameter HeaderHeight. Is there a way that I can make HeaderHeight ignored by the StackLayout if it's not specified in the XAML that calls the template?

<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:Japanese;assembly=Japanese" x:Class="Japanese.Templates.HeaderTemplate" x:Name="this">
    <ContentView.Triggers>
        <Trigger TargetType="local:Templates.HeaderTemplate" Property="HeaderType" Value="Custom">
            <Setter Property="Content">
                <Setter.Value>
                    <StackLayout HorizontalOptions="FillAndExpand" Orientation="Vertical" Spacing="0" Margin="0">
                        <StackLayout HeightRequest="{Binding HeaderHeight, Source={x:Reference this}}" Orientation="Vertical" Spacing="0" Margin="0" >
                            <Label Text="ABC" HorizontalOptions="Start" VerticalOptions="EndAndExpand" />
                        </StackLayout>
                    </StackLayout>
                </Setter.Value>
            </Setter>
        </Trigger>
    </ContentView.Triggers>
</ContentView>
xamarin.forms xamarin
1 Answers

You can set the default value of HeaderHeight to -1

The UI should go back to normal

HeaderHeight = -1;

Once it's a BindableProperty, it should look like this:

public static readonly BindableProperty HeaderHeightProperty = BindableProperty.Create(nameof(HeaderHeight), typeof(double), typeof(HeaderTemplate), -1);
public double HeaderHeight
{
    get => (double)GetValue(HeaderHeightProperty);
    set => SetValue(HeaderHeightProperty, value);
}
user_17525620
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