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问题[converters](coding)

Martin Hope
Frank Mehlhop
Asked: 2023-08-17 16:59:07 +0800 CST
  • 5

我将通过布尔变量将 StaticResource 颜色作为 BackgroundColor 绑定到 Shell（在 AppShell.xaml 中）。我的解决方案不起作用。我总是得到默认的背景颜色（参见底部的样式）。我从来没有得到Yellow100或Gray500。 错误在哪里呢？

<Shell ...  
    xmlns:viewModels="clr-namespace:MyApp.ViewModels"
    x:DataType="viewModels:AppShellViewModel"
    BackgroundColor="{Binding IsOnline, Converter={StaticResource BoolToColorConverter}}" >

    <Shell.Resources>
        <ResourceDictionary>
            <toolkit:IsStringNotNullOrEmptyConverter x:Key="IsStringNotNullOrEmptyConverter" />
            <toolkit:BoolToObjectConverter x:Key="BoolToColorConverter" TrueObject="{StaticResource Yellow100}" FalseObject="{StaticResource Gray500}" />
        </ResourceDictionary>
    </Shell.Resources>

我还尝试使用x:TypeArguments="Color"或x:DataType="Color"

我的视图模型：

public partial class AppShellViewModel : ObservableObject
{
    [ObservableProperty]
    private bool _isOnline;

    public AppShellViewModel(ConnectionStateService connectionStateService)
    {
        IsOnline = connectionStateService.IsOnline();
    }
}

我的颜色.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">

    <Color x:Key="Gray500">#6E6E6E</Color>
    <Color x:Key="Yellow100">#F7B548</Color>

我尝试过这个并且效果很好：

BackgroundColor="{StaticResource Yellow100Accent}"

默认颜色是通过 Styles.xaml 中的 Style 设置的：

<Style TargetType="Shell" ApplyToDerivedTypes="True">
    <Setter Property="Shell.BackgroundColor"
            Value="{AppThemeBinding Light={StaticResource Primary}, Dark={StaticResource Gray950}}" /> ...

AppShell.xaml.cs：

public partial class AppShell
{
    private readonly AppShellViewModel _appShellViewModel;

    public AppShell(AppShellViewModel appShellAppShellViewModel)
    {
        _appShellViewModel = appShellAppShellViewModel;

        BindingContext = _appShellViewModel;

        InitializeComponent();

        Routing.RegisterRoute(nameof(FirstPage), typeof(FirstPage));
        Routing.RegisterRoute(
    ...
    } ....
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