DataTrigger链接到资源。 Xamarin表格

Question

Need to change Page Background . I have such class:

class DataClass:INotifyPropertyChanged
{
    private string currentTheme;

    public string CurrentTheme
    {
        get { return currentTheme; }
        set
        {
            currentTheme = value;
            OnPropertyChanged("CurrentTheme");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string property)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
    }
}

Have Data and Style in ResourseDictionary of my app:

<local:DataClass x:Key="Data" CurrentTheme="Default"/>

        <!-- Styles -->

        <Style x:Key="Page"
               TargetType="ContentPage">

            <Style.Triggers>

                <!-- Need to bind it to Data-->
                <DataTrigger >
                  <Setter Property="BackgroundColor"
                          Value="Aqua"/>
                </DataTrigger>

            </Style.Triggers>

        </Style>

Can't bind DataTrigger to Data.CurrentTheme . Tried BindingContext but mostly have errors. Pls, help

Answer 1

If you are trying to theme your application and needs to change the theme in between, then you will be better of using the new Xamarin.Forms Themes . You can either use the pre built light and dark theme via nuget or create your own local themes and use it through out your application.

Creating a Custom Theme walks you through all the steps in detail on how to create the theme and use it.

DataTriggers are very similar to PropertyTriggers, except that instead of specifying the Property, we specify the Binding for the trigger. This Binding generally refers to another VisualElement's property on the page or it could reference a property in a ViewModel.

Eg : To disable the button when the entry's Text.Length property is 0.

<StackLayout Spacing="20">
<Entry x:Name="emailAddress" Text="" Placeholder="email address"/>
<Button Text="Send">
  <Button.Triggers>
    <DataTrigger TargetType="Button"
         Binding="{Binding Source={x:Reference emailAddress},Path=Text.Length}" Value="0">
      <Setter Property="IsEnabled" Value="False" />
    </DataTrigger>
  </Button.Triggers>
</Button>
</StackLayout>

If you need more information then read Data Triggers and Triggers in Xamarin.Forms