C# 如何使用触发器更改 TextBlock 的可见性？
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How can I change the Visibility of a TextBlock with a Trigger?
提问by Edward Tanguay
When I try to compile the following code, I get the error 'Visibility' member is not valid because it does not have a qualifying type name.
当我尝试编译以下代码时，我收到错误“可见性”成员无效，因为它没有限定类型名称。
What do I have to change so that I can make the TextBlock disappearwhen Status=off?
我必须更改什么才能在 Status=off 时使 TextBlock 消失？
XAML:
XAML：
<Window x:Class="TestTrigger123345.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<StackPanel>
<TextBlock Text="This is a sentence.">
<TextBlock.Triggers>
<Trigger Property="{Binding Status}" Value="off">
<Setter Property="Visibility" Value="Collapsed"/>
</Trigger>
</TextBlock.Triggers>
</TextBlock>
<TextBlock Text="{Binding Status}"/>
</StackPanel>
</Window>
Code Behind:
背后的代码：
using System.Windows;
namespace TestTrigger123345
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
DataContext = this;
Status = "off";
}
public string Status { get; set; }
}
}
I changed to DataTrigger and Dependency Properties and it gets the same error:
我更改为 DataTrigger 和 Dependency Properties 并得到相同的错误：
XAML:
XAML：
<Window x:Class="TestTrigger123345.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<StackPanel HorizontalAlignment="Left">
<TextBlock Text="{Binding Status}">
<TextBlock.Triggers>
<DataTrigger Binding="{Binding Status}" Value="off">
<Setter Property="TextBlock.Background" Value="Tan"/>
</DataTrigger>
</TextBlock.Triggers>
</TextBlock>
</StackPanel>
</Window>
Code Behind:
背后的代码：
using System.Windows;
namespace TestTrigger123345
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
DataContext = this;
Status = "off";
}
#region DependencyProperty: Status
public string Status
{
get
{
return (string)GetValue(StatusProperty);
}
set
{
SetValue(StatusProperty, value);
}
}
public static readonly DependencyProperty StatusProperty =
DependencyProperty.Register("Status", typeof(string), typeof(Window1),
new FrameworkPropertyMetadata());
#endregion
}
}
I redid this with a ViewModel that has a property Status that implements INotifyPropertyChanged, and it gets that same error:
我使用具有实现 INotifyPropertyChanged 的属性 Status 的 ViewModel 重新执行此操作，并且它得到相同的错误：
WindowViewModel.cs:
WindowViewModel.cs：
using System.ComponentModel;
namespace TestTrigger123345
{
class WindowViewModel
{
#region ViewModelProperty: Status
private string _status;
public string Status
{
get
{
return _status;
}
set
{
_status = value;
OnPropertyChanged("Status");
}
}
#endregion
#region PropertChanged Block
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
#endregion
}
}
Code Behind:
背后的代码：
using System.Windows;
namespace TestTrigger123345
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
WindowViewModel windowViewModel = new WindowViewModel();
windowViewModel.Status = "off";
DataContext = windowViewModel;
}
}
}
Surely there is a way to do this with a trigger somehow.
当然，有一种方法可以通过触发器以某种方式做到这一点。
回答by rockeye
Maybe you need to implement INotifyPropertyChanged and raise PropertyChange when Status change ?
也许您需要实现 INotifyPropertyChanged 并在 Status 更改时引发 PropertyChange ？
Instead of using a trigger, you can use a Converter between Visibility and your Status string.
您可以在可见性和状态字符串之间使用转换器，而不是使用触发器。
回答by Arcturus
For Bindings use DataTrigger, for properties you can use Trigger.. Also make sure the Status Property notifies ;) Either make it a dependency property or use the INotifyPropertyChanged interface.
对于绑定，使用 DataTrigger，对于属性，您可以使用 Trigger.. 还要确保 Status 属性通知 ;) 要么使其成为依赖属性，要么使用 INotifyPropertyChanged 接口。
回答by Will Perry
You need to specify the Type on which the visibility should be set
您需要指定应设置可见性的类型
<Setter Property="FrameworkElement.Visibility" Value="Visible"/>
回答by Tecky
Triggers of an element only support EventTrigger so you can't use property triggers (Trigger). Look FrameworkElement.Triggers Property.
元素的触发器仅支持 EventTrigger，因此您不能使用属性触发器（Trigger）。看看 FrameworkElement.Triggers 属性。
回答by Yuri Perekupko
Try something like this:
尝试这样的事情：
<PasswordBox Name="pbxPassword" />
<TextBox Text="{Binding Password,
ElementName=pbxPassword,
UpdateSourceTrigger=PropertyChanged}">
<TextBox.Style>
<Style TargetType="TextBox">
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding IsChecked, ElementName=chbShowPassword}" Value="True">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
<CheckBox Name="chbShowPassword">
Show password
</CheckBox>
