命令执行时按钮不会被禁用

Question

我喜欢 MVVM Light 框架，正如很多人所说，简单但功能强大。

我正在尝试禁用一个按钮，执行与 EventToCommand 示例中相同的操作（工作正常，但有针对性或 3.5）。我添加了一个 IsEnabled 事件，正在触发。

我的程序目标是4.0。

我的命令被禁用了，但按钮保持启用状态。

我也在我的程序中添加了一个事件，但没有触发。

不知道我错过了什么。

我的Xaml：

<Window x:Class="MyWPFApp.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
    xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.WPF4"
    xmlns:vw="clr-namespace:MyWPFApp.Views"

    Title="MainWindow"
    Height="300"
    Width="300"
    SizeToContent="WidthAndHeight"
    DataContext="{Binding Source={StaticResource Locator}, Path=v_MainWindow}">

<Window.Resources>
    <!--<ResourceDictionary x:Key="ResDict">
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="/Skins/MainSkin.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>-->
    <ControlTemplate x:Key="ButtonTemplate"
                     TargetType="Button">
        <Grid x:Name="Root"
              Opacity="0.8"
              RenderTransformOrigin="0.5,0.5">
            <Grid.RenderTransform>
                <TransformGroup>
                    <ScaleTransform />
                    <SkewTransform />
                    <RotateTransform />
                    <TranslateTransform />
                </TransformGroup>
            </Grid.RenderTransform>

            <VisualStateManager.VisualStateGroups>
                <VisualStateGroup x:Name="CommonStates">
                    <VisualStateGroup.Transitions>
                        <VisualTransition From="MouseOver"
                                          GeneratedDuration="00:00:00.2000000"
                                          To="Normal" />
                        <VisualTransition From="Normal"
                                          GeneratedDuration="00:00:00.2000000"
                                          To="MouseOver" />
                    </VisualStateGroup.Transitions>
                    <VisualState x:Name="Normal" />
                    <VisualState x:Name="MouseOver">
                        <Storyboard>
                            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
                                                           Duration="00:00:00.0010000"
                                                           Storyboard.TargetName="Root"
                                                           Storyboard.TargetProperty="(UIElement.Opacity)">
                                <SplineDoubleKeyFrame KeyTime="00:00:00"
                                                      Value="1" />
                            </DoubleAnimationUsingKeyFrames>
                        </Storyboard>
                    </VisualState>
                    <VisualState x:Name="Pressed">
                        <Storyboard>
                            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
                                                           Duration="00:00:00.0010000"
                                                           Storyboard.TargetName="Root"
                                                           Storyboard.TargetProperty="(UIElement.Opacity)">
                                <SplineDoubleKeyFrame KeyTime="00:00:00"
                                                      Value="1" />
                            </DoubleAnimationUsingKeyFrames>
                            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
                                                           Duration="00:00:00.0010000"
                                                           Storyboard.TargetName="Root"
                                                           Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)">
                                <SplineDoubleKeyFrame KeyTime="00:00:00"
                                                      Value="0.9" />
                            </DoubleAnimationUsingKeyFrames>
                            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
                                                           Duration="00:00:00.0010000"
                                                           Storyboard.TargetName="Root"
                                                           Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)">
                                <SplineDoubleKeyFrame KeyTime="00:00:00"
                                                      Value="0.9" />
                            </DoubleAnimationUsingKeyFrames>
                        </Storyboard>
                    </VisualState>
                    <VisualState x:Name="Disabled">
                        <Storyboard>
                            <DoubleAnimationUsingKeyFrames BeginTime="00:00:00"
                                                           Duration="00:00:00.0010000"
                                                           Storyboard.TargetName="Root"
                                                           Storyboard.TargetProperty="(UIElement.Opacity)">
                                <SplineDoubleKeyFrame KeyTime="00:00:00"
                                                      Value="0.4" />
                            </DoubleAnimationUsingKeyFrames>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateManager.VisualStateGroups>
            <Rectangle Fill="{TemplateBinding Background}"
                       Stroke="Black"
                       RadiusX="8"
                       RadiusY="8" />
            <TextBlock HorizontalAlignment="Center"
                       VerticalAlignment="Center"
                       Text="{TemplateBinding Content}"
                       TextWrapping="Wrap"
                       FontSize="12"
                       FontWeight="Bold" />
        </Grid>
    </ControlTemplate>

    <Style x:Key="ButtonStyle"
           TargetType="Button">
        <Setter Property="Template"
                Value="{StaticResource ButtonTemplate}" />
        <Setter Property="Cursor"
                Value="Hand" />
    </Style>

</Window.Resources>

<Grid x:Name="LayoutRoot">
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="Auto" />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <StackPanel Grid.Row="0"  Grid.Column="0" Orientation="Vertical" HorizontalAlignment="Left">
        <Button Content="Change to Error Status" Style="{StaticResource ButtonStyle}" IsEnabledChanged="EnableChanged">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <cmd:EventToCommand Command="{Binding StatusCommand}"
                                   CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=Button}, Path=Content}" MustToggleIsEnabled="True"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
        <Button Content="Change to Warning" Style="{StaticResource ButtonStyle}" IsEnabledChanged="EnableChanged">              
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="Click">
                    <cmd:EventToCommand Command="{Binding StatusCommand}"
                                       CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=Button}, Path=Content}" MustToggleIsEnabled="True"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </Button>
        <Button Content="Success" IsEnabled="False"/>
        <Button Content="Info"/>
    </StackPanel>
    <TextBlock Grid.Row="0"  Grid.Column="1"
               FontSize="36"
               FontWeight="Bold"
               Foreground="Purple"
               Text="{Binding Welcome}"
               VerticalAlignment="Center"
               HorizontalAlignment="Center"
               TextWrapping="Wrap">
       <!--<i:Interaction.Triggers>
           <i:EventTrigger EventName="MouseEnter">
               <cmd:EventToCommand Command="{Binding StatusCommand}"
                                   CommandParameter="Error" />
           </i:EventTrigger>
       </i:Interaction.Triggers>-->
    </TextBlock>
    <vw:v_StatusBar Grid.Row="1" Grid.ColumnSpan="2" />

</Grid>

我在视图模型中的代码

using System.Windows;
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using GalaSoft.MvvmLight.Messaging;



namespace MyWPFApp.ViewModel
{
/// <summary>
/// This class contains properties that the main View can data bind to.
/// <para>
/// Use the <strong>mvvminpc</strong> snippet to add bindable properties to this ViewModel.
/// </para>
/// <para>
/// You can also use Blend to data bind with the tool's support.
/// </para>
/// <para>
/// See http://www.galasoft.ch/mvvm/getstarted
/// </para>
/// </summary>
public class vm_MainWindow : ViewModelBase
{
    public string Welcome
    {
        get
        {
            return "Welcome to Geert's WPF template (based on MVVM Light)";
        }
    }

    private string _status = "Initialized...";

    public string Status
    {
        get
        {
            return _status;
        }

        private set
        {
            if (_status == value)
            {
                MessageBox.Show("Status is already " + value);
                return;
            }

            _status = value;

            MessageBox.Show("Setting status to " + _status);
            Messenger.Default.Send<string>(value, "StatusChange");

        }
    }

    public RelayCommand<string> StatusCommand
    {
        get;
        private set;
    }


    /// <summary>
    /// Initializes a new instance of the MainViewModel class.
    /// </summary>
    public vm_MainWindow()
    {
        if (IsInDesignMode)
        {
            // Code runs in Blend --> create design time data.
        }
        else
        {
            // Code runs "for real"

            StatusCommand = new RelayCommand<string>(p => Status = string.Format("{0}", p), p => p != _status);

        }
    }

    ////public override void Cleanup()
    ////{
    ////    // Clean up if needed

    ////    base.Cleanup();
    ////}
}

}

Answer 1

发现问题了，CanExecuteChanged 简单从来没有触发！！！！！！

首先，我（在中继命令中）添加了注释中建议的内容：
http://msdn.microsoft.com/query/dev10.query?appId= Dev10IDEF1&l=EN-US&k=k(SYSTEM.WINDOWS.INPUT.COMMANDMANAGER.REQUERYSUGGESTED);k(TargetFrameworkMoniker-%22.NETFRAMEWORK%2cVERSION%3dV4.0%22);k(DevLang-CSHARP)&rd =true

然后我注意到只有最后一个按钮被启用/禁用。

再次合乎逻辑的是，relaycommand 中添加的每个处理程序都会覆盖前一个处理程序。

因此，我在 eventtocommand 中添加了事件处理支持。

并且，一切正常。

会将我的更正发送给 Buignon 先生，希望他能检查并正式发布。

ps 仅针对 WPF 4.0 检查和更改（我现在唯一需要的东西）