好的，所以這絕對是一個新手問題，不幸的是無法找到/找到答案。
本質上將物件串列系結到組合框，當Disabled物件的屬性設定為 true 時，我希望將組合框項的文本顏色設定為灰色。
這是我到目前為止所擁有的：
組合框項資料型別
public class ListItem
{
public ListItem(string text)
{
Text = text;
}
public string Text { get; set; }
public bool Disabled { get; set; }
}
視圖模型設定
public class MainPageViewModel : ReactiveObject
{
// In ReactiveUI, this is the syntax to declare a read-write property
// that will notify Observers, as well as WPF, that a property has
// changed. If we declared this as a normal property, we couldn't tell
// when it has changed!
private ListItem _selectedItem;
public ListItem SelectedItem
{
get => _selectedItem;
set => this.RaiseAndSetIfChanged(ref _selectedItem, value);
}
public List<ListItem> Items { get; set; }
public MainPageViewModel()
{
Items = new List<ListItem>
{
new ListItem ("A Cat"),
new ListItem ("A Dog"),
new ListItem ("A Mouse"),
new ListItem ("A Frog") { Disabled = true }
};
}
}
ReactiveUI 系結
public MainPage()
{
InitializeComponent();
ViewModel = new MainPageViewModel();
this.WhenActivated(d =>
{
this.OneWayBind(ViewModel, vm => vm.Items, v => v.MyComboBox.ItemsSource)
.DisposeWith(d);
this.Bind(ViewModel, vm => vm.SelectedItem, v => v.MyComboBox.SelectedItem)
.DisposeWith(d);
});
}
Xaml 標記
<ComboBox
Name="MyComboBox"
Margin="0,0,0,20"
Foreground="black">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" />
</DataTemplate>
</ComboBox.ItemTemplate>
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Disabled}" Value="True">
<Setter Property="Foreground" Value="Gray" />
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
如果您需要更多資訊，請告訴我任何幫助。
uj5u.com熱心網友回復：
下拉串列中的最后一項文本已灰顯，因此我假設您正在詢問所選專案。ComboBox對所選專案和下拉串列中的專案使用單獨的資料模板。您可以使用 aDataTemplateSelector來設定兩者。
public class ComboBoxTemplateSelector : DataTemplateSelector
{
public DataTemplate SelectedItemTemplate { get; set; }
public DataTemplate DropdownItemsTemplate { get; set; }
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
var itemToCheck = container;
// Search up the visual tree, stopping at either a ComboBox or a ComboBoxItem (or null).
// This will determine which template to use.
while (itemToCheck is not null and not ComboBox and not ComboBoxItem)
itemToCheck = VisualTreeHelper.GetParent(itemToCheck);
// If you stopped at a ComboBoxItem, you're in the dropdown.
return itemToCheck is ComboBoxItem ? DropdownItemsTemplate : SelectedItemTemplate;
}
}
Xaml 標記
<StackPanel>
<StackPanel.Resources>
<Style x:Key="GrayedOutText" TargetType="TextBlock">
<Style.Triggers>
<DataTrigger Binding="{Binding Disabled}" Value="True">
<Setter Property="Foreground" Value="Gray" />
</DataTrigger>
</Style.Triggers>
</Style>
<local:ComboBoxTemplateSelector x:Key="ComboBoxTemplateSelector">
<local:ComboBoxTemplateSelector.SelectedItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Text}" Style="{StaticResource GrayedOutText}" />
</DataTemplate>
</local:ComboBoxTemplateSelector.SelectedItemTemplate>
<local:ComboBoxTemplateSelector.DropdownItemsTemplate>
<DataTemplate>
<TextBlock Text="{Binding Text}" Style="{StaticResource GrayedOutText}" />
</DataTemplate>
</local:ComboBoxTemplateSelector.DropdownItemsTemplate>
</local:ComboBoxTemplateSelector>
</StackPanel.Resources>
<ComboBox
Name="MyComboBox"
Margin="0,0,0,20"
ItemTemplateSelector="{StaticResource ComboBoxTemplateSelector}">
</ComboBox>
</StackPanel>
我們在DataTemplate定義中有一些重復，但這些在生產代碼中往往會分開。
資源
- 我可以為 WPF ComboBox 中的選定專案使用與下拉部分中的專案不同的模板嗎？
- https://www.reactiveui.net/docs/getting-started/compelling-example
uj5u.com熱心網友回復：
這是一種在我的測驗中有效的方法：
組合框項資料型別
//-- Unchanged
public class ListItem
{
public ListItem( string text )
{
Text = text;
}
public string Text { get; set; }
public bool Disabled { get; set; }
}
視圖模型設定
public class MainPageViewModel : INotifyPropertyChanged
{
private ListItem? _selectedItem;
public event PropertyChangedEventHandler? PropertyChanged;
public ListItem? SelectedItem
{
get => _selectedItem;
set
{
//-- I didn't had the "RaiseAndSetIfChanged" method, so I just implemented the functionality manually
if( value != _selectedItem )
{
//-- Update the value ...
_selectedItem = value;
//-- ... AND inform everyone (who is interested) about the change
this.PropertyChanged?.Invoke( this, new PropertyChangedEventArgs( nameof( this.SelectedItem ) ) );
}
}
}
//-- Use always an ObservableCollection when you want to archieve reactivity
public ObservableCollection<ListItem> Items
{ get; } = new ObservableCollection<ListItem>();
public MainPageViewModel()
{
//-- Add some test data
this.Items.Add( new ListItem( "A Cat" ) );
this.Items.Add( new ListItem( "A Dog" ) );
this.Items.Add( new ListItem( "A Mouse" ) );
this.Items.Add( new ListItem( "A Frog" ) { Disabled = true } );
//-- Just select the first item
this.SelectedItem = this.Items[0];
}
}
主頁
public MainPage()
{
//-- Define the DataContext BEFORE the UI will be initialized ;)
this.DataContext = new MainPageViewModel();
InitializeComponent();
//-- Never saw such code before -> just don't do that ;)
//this.WhenActivated( d =>
//{
// this.OneWayBind( ViewModel, vm => vm.Items, v => v.MyComboBox.ItemsSource )
// .DisposeWith( d );
// this.Bind( ViewModel, vm => vm.SelectedItem, v => v.MyComboBox.SelectedItem )
// .DisposeWith( d );
//} );
}
Xaml 標記
<DockPanel>
<ComboBox
DockPanel.Dock="Top"
Name="MyComboBox"
Margin="0,0,0,20"
Foreground="black"
ItemsSource="{Binding Items}"
SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Text}" />
</DataTemplate>
</ComboBox.ItemTemplate>
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Disabled}" Value="True">
<Setter Property="Foreground" Value="Gray" />
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
<!-- Details View -->
<StackPanel>
<!-- name -->
<StackPanel Orientation="Horizontal">
<Label Content="Item Name" />
<TextBox Text="{Binding SelectedItem.Text}" />
</StackPanel>
<!-- disabled flag -->
<StackPanel Orientation="Horizontal">
<Label Content="IsDisabled" />
<CheckBox IsChecked="{Binding SelectedItem.Disabled}" />
</StackPanel>
</StackPanel>
</DockPanel>
我希望這能滿足您的要求。玩得開心 ：）
uj5u.com熱心網友回復：
我假設您的問題是ComboBoxItem應用程式運行后 s 不會變灰。
我對ReactiveUI不熟悉，但是由于我在您的代碼中發現了問題，因此我在您的代碼的CommunityToolkit.Mvvm版本中進行了嘗試并驗證了我的理論。
最重要的是，您需要對屬性實作ReactiveUI版本。INotifyPropertyChangedDisabled
如果您有興趣，我可以發布此代碼的CommunityToolkit.Mvvm版本。
轉載請註明出處，本文鏈接：https://www.uj5u.com/ruanti/506341.html
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