如何使用触发器更改 TextBlock 的可见性？

Question

当我尝试编译以下代码时，我收到错误 'Visibility' member is not valid because it does not have aqualified type name.

我必须进行哪些更改才能在 Status=off 时使 TextBlock 消失？

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>

代码隐藏：

using System.Windows;

namespace TestTrigger123345
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            DataContext = this;
            Status = "off";
        }

        public string Status { get; set; }

    }
}

我更改为 DataTrigger 和 Dependency Properties 并得到相同的错误：

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>

代码隐藏：

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


    }
}

我使用具有实现 INotifyPropertyChanged 的​​属性 Status 的 ViewModel 重新执行此操作，但它得到了同样的错误：

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
    }
}

代码隐藏：

using System.Windows;

namespace TestTrigger123345
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            WindowViewModel windowViewModel = new WindowViewModel();
            windowViewModel.Status = "off";
            DataContext = windowViewModel;
        }

    }
}

当然有办法通过某种方式使用触发器来做到这一点。

Answer 1

也许您需要实现 INotifyPropertyChanged 并在 Status 更改时引发 PropertyChange ？

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。

Answer 2

对于 Bindings 使用 DataTrigger，对于属性，您可以使用 Trigger.. 还要确保 Status 属性通知 ;) 使其成为依赖属性或使用 INotifyPropertyChanged 接口。

DataTrigger on MSDN

Nice article how to combine all these trigger goodness

Answer 3

您需要指定应设置可见性的类型

<Setter Property="FrameworkElement.Visibility" Value="Visible"/>

Answer 4

元素的触发器只支持EventTrigger，所以不能使用属性触发器（Trigger）。查看 FrameworkElement.Triggers 属性。

Answer 5

试试这样的：

<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>