Chemmy's Blog

大家好

说起子窗体，大家都会想到ChildWindow，多熟悉的一个控件。不错，Sliverlight中已经提供了子窗体的具体实现，而在WPF中却没有这么好的事情（有的第三方控件商已经提供此控件）。最常见的实现方法就是在ViewModel中，直接New ChildWindow，然后直接Show。这样的方法也达到的要求。但是它不符合MVVM分层思想，再就是代码不美观，难以维护，今天我就给大家介绍一种美观又实用的方法。

原理

通过Prism中提供的InteractionRequestTrigger事件触发器，实现点击按钮或者用户的某种操作弹出对话框的效果。另外，不要忘了引用此命名空间：

using Microsoft.Practices.Prism.Interactivity.InteractionRequest;

创建ChildWindow窗体

<Window x:Class=”ChildWindowDemo.ChildWindow.ChildWindow” xmlns=“http://schemas.microsoft.com/winfx/2006/xaml/presentation“ xmlns:x=“http://schemas.microsoft.com/winfx/2006/xaml“ xmlns:i=“http://schemas.microsoft.com/expression/2010/interactivity“ xmlns:ei=“http://schemas.microsoft.com/expression/2010/interactions“ Width=“300” Height=”150” Title=“{Binding Title}” x:Name=“confirmationWindow” Topmost=”True” WindowStyle=”ToolWindow” WindowStartupLocation=”CenterScreen”>
<Grid x:Name=”LayoutRoot” Margin=”2”>
<Grid.RowDefinitions>


</Grid.RowDefinitions>

    <ContentControl HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Grid.Row="0" Content="{Binding Content}"/>

    <Button Content="Cancel" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,0,0" Grid.Row="1"\>
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Click"\>
                <ei:CallMethodAction TargetObject="{Binding ElementName=confirmationWindow}" MethodName="Close"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </Button>
    <Button Content="OK" Width="75" Height="23" HorizontalAlignment="Right" Margin="0,12,79,0" Grid.Row="1"\>
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="Click"\>
                <ei:ChangePropertyAction PropertyName="Confirmed" TargetObject="{Binding}" Value="True"/>
                <ei:CallMethodAction TargetObject="{Binding ElementName=confirmationWindow}" MethodName="Close"/>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </Button>
</Grid>

创建ChildWindow的基类

新建类：ChildWindowActionBase 并从TriggerAction派生，代码如下：

public class ChildWindowActionBase : TriggerAction<FrameworkElement> { protected override void Invoke(object parameter)
    { var arg = parameter as InteractionRequestedEventArgs; if (arg == null) return; var windows = this.GetChildWindow(arg.Context); var callback = arg.Callback;
        EventHandler handler \= null;
        handler \= (o, e) \=> {
                windows.Closed \-= handler;
                callback();
            };
        windows.Closed += handler;

        windows.ShowDialog();

    }

    Window GetChildWindow(Notification notification)
    { var childWindow = this.CreateDefaultWindow(notification);
        childWindow.DataContext \= notification; return childWindow;
    }

    Window CreateDefaultWindow(Notification notification)
    { return (Window)new ChildWindow.ChildWindow();
    }
} 

到此子窗体已经完成

如何调用

主程序界面代码如下：

<Window x:Class=”ChildWindowDemo.MainWindow” xmlns=“http://schemas.microsoft.com/winfx/2006/xaml/presentation“ xmlns:x=“http://schemas.microsoft.com/winfx/2006/xaml“ xmlns:d=“http://schemas.microsoft.com/expression/blend/2008“ xmlns:mc=“http://schemas.openxmlformats.org/markup-compatibility/2006“ xmlns:prism=“http://www.codeplex.com/prism“ xmlns:i=“http://schemas.microsoft.com/expression/2010/interactivity“ xmlns:local=“clr-namespace:ChildWindowDemo” Title=“MainWindow” Height=”200” Width=”300”>
<i:Interaction.Triggers>
<prism:InteractionRequestTrigger SourceObject=”{Binding ConfirmationRequest, Mode=OneWay}”>
local:ChildWindowActionBase/

</i:Interaction.Triggers>

对之对应的ViewModel：

public class MainWindowViewModel : NotificationObject
{ public MainWindowViewModel()
    { this.RaiseConfirmation = new DelegateCommand(this.OnRaiseConfirmation); this.ConfirmationRequest = new InteractionRequest<Confirmation>();
    } public InteractionRequest<Confirmation> ConfirmationRequest { get; private set; } public DelegateCommand RaiseConfirmation { get; private set; } private string result; public string ConfirmationResult
    { get { return result; } set {
            result \= value; this.RaisePropertyChanged(() => this.ConfirmationResult);
        }
    } private void OnRaiseConfirmation()
    { this.ConfirmationRequest.Raise( new Confirmation { Content = "是否确认", Title = "子窗体" },
            (cb) \=> { ConfirmationResult = cb.Confirmed ? "确认" : "取消"; });
    }      
}

总结

这样的写法比较符合MVVM的分层思想，子窗体可以随心定制，而不需要去改逻辑层的代码。具体代码以上全部提供，谢谢。