Converting Image Trigger from XAML to C# Markup-CodePudding

I have an arrow image that rotates when an expander is expanded. I'm trying to convert the XAML code to C#, I can see the arrow and the app theme binding works in the c# code except that it is not rotating.

xaml:

<Image
    HeightRequest="25"
    HorizontalOptions="End"
    Source="{AppThemeBinding Light=down_arrow.png,
                                Dark=down_arrow_dark.png}"
    VerticalOptions="Start">
    <Image.Triggers>
        <DataTrigger
            Binding="{Binding Source={RelativeSource AncestorType={x:Type mct:Expander}}, Path=IsExpanded}"
            TargetType="Image"
            Value="True">
            <Setter Property="Rotation" Value="180" />
        </DataTrigger>
    </Image.Triggers>
</Image>

Current C# code:

var arrowImage = new Image()
{
    Triggers = 
    {
        new DataTrigger(typeof(Image))
        {
            Value = true,
            Binding = new Binding(nameof(expander.IsExpanded)),
            Setters =
            {
                new Setter()
                {
                    Property = Image.RotationProperty,
                    Value = 180
                }
            }
        }
    },
    HeightRequest = 25,
    HorizontalOptions = LayoutOptions.End,
};
arrowImage.SetAppTheme<FileImageSource>(Image.SourceProperty, "down_arrow.png", "down_arrow_dark.png");

CodePudding user response：

I had to set the Source and have a trigger for Value = false for it to behave the same as XAML.

var arrowImage = new Image()
{
    Triggers = 
    {
        new DataTrigger(typeof(Image))
        {
            Value = true,
            Binding = new Binding(nameof(expander.IsExpanded), BindingMode.Default, null, null, null, expander),
            Setters =
            {
                new Setter()
                {
                    Property = Image.RotationProperty,
                    Value = 180
                }
            }
        },
        new DataTrigger(typeof(Image))
        {
            Value = false,
            Binding = new Binding(nameof(expander.IsExpanded), BindingMode.Default, null, null, null, expander),
            Setters =
            {
                new Setter()
                {
                    Property = Image.RotationProperty,
                    Value = 0
                }
            }
        },
    },
    HeightRequest = 25,
    HorizontalOptions = LayoutOptions.End,
};