如何在Xamarin页面上添加可以以默认样式使用的属性？

Question

I have added a BarTextColor property to my custom Xamarin page, like so:

    public static readonly BindableProperty BarTextColorProperty = BindableProperty.Create("BarTextColor", typeof(Color), typeof(MyCustomPage), Color.Default);

    public Color BarTextColor
    {
        get { return (Color)GetValue(BarTextColorProperty); }
        set { SetValue(BarTextColorProperty, value); UpdateInnerViews(); }
    }

But when I try to set a global style in my App.xaml like so:

    <Style TargetType="myapp:MyCustomPage">
        <Setter Property="BarTextColor" Value="{StaticResource BarTextColor}"/>
    </Style>

I get this error:

Property 'BarTextColor' must be a DependencyProperty to be set with a Setter

and this:

The property "BarTextColor" is not a DependencyProperty. To be used in markup, non-attached properties must be exposed on the target type with an accessible instance property "BarTextColor". For attached properties, the declaring type must provide static "GetBarTextColor" and "SetBarTextColor" methods.

What's going wrong? The Xamarin source on github all uses BindableProperty not DependencyProperty , so why can't I?

(I'm using Visual Studio Community 2013 with Xamarin 2.3.1, in case it matters)

Answer 1

I created BasePage.cs :

public class BasePage : ContentPage
{
    public static readonly BindableProperty BarTextColorProperty =
        BindableProperty.Create(nameof(BarTextColor),
                                typeof(Color),
                                typeof(BasePage),
                                Color.White,
                                propertyChanged: OnColorChanged);

    private static void OnColorChanged(BindableObject bindable, object oldValue, object newValue)
    {
    }

    public Color BarTextColor
    {
        get { return (Color)GetValue(BarTextColorProperty); }
        set { SetValue(BarTextColorProperty, value); }
    }
}

Then created some ContentPage :

<local:BasePage xmlns="http://xamarin.com/schemas/2014/forms"
                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                xmlns:local="clr-namespace:SuperForms.Samples.CustomPropertySample;assembly=SuperForms.Samples"
                x:Class="SuperForms.Samples.CustomPropertySample.Page1"
                Style="{StaticResource BasePageStyle}">
    <Label Text="Alloha" VerticalOptions="Center" HorizontalOptions="Center" />
</local:BasePage>

public partial class Page1 : BasePage
{
    public Page1()
    {
        InitializeComponent();
    }
}

And declared Style in App.xaml :

<Application xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:customPropertySample="clr-namespace:SuperForms.Samples.CustomPropertySample;assembly=SuperForms.Samples"
         x:Class="SuperForms.Samples.App">
    <Application.Resources>
        <ResourceDictionary>
            <Style x:Key="BasePageStyle" TargetType="customPropertySample:BasePage">
                <Setter Property="BarTextColor" Value="#ff0000"/>
            </Style>
        </ResourceDictionary>
    </Application.Resources>
</Application>

But I used Style by Key , because it didn't work w/o Key . And on OnColorChanged I've got red color from Style .

Edited

Or you could create base page for navigation:

public class BaseNavigationPage : NavigationPage
{
    public BaseNavigationPage(ContentPage root) 
        : base(root)
    {

    }

    public BaseNavigationPage()
    {
        BarBackgroundColor = Color.Red;
    }
}

And use it for Navigation:

    public App()
    {
        InitializeComponent();

        MainPage = new CustomPropertySample.BaseNavigationPage(new CustomPropertySample.Page1());
    }