在WPF中,MVVM是否应该让ViewModel参与打开窗口,例如About-window?
我有一个标准的 WPF 树视图,并绑定了查看模型类的项目。
我现在希望处理双击项目时的行为(打开视觉工作室风格的文档)。
我可以让事件处理程序在包含树视图的控件中触发(显示的 xaml),但是如何绑定到视图模型类上的特定行为 - 例如 ProjectViewModel?
最好绑定到 ICommand-implementer,因为这在其他地方使用...
感谢您的任何评论,
Anders,丹麦
<TreeView ItemsSource="{Binding Projects}" MouseDoubleClick="TreeView_MouseDoubleClick">
<TreeView.ItemContainerStyle>
<!--
This Style binds a TreeViewItem to a TreeViewItemViewModel.
-->
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight" Value="Normal" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type Implementations:ProjectViewModel}" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\Region.png" />
<TextBlock Text="{Binding DisplayName}" />
</StackPanel>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type Implementations:PumpViewModel}" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\State.png" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</HierarchicalDataTemplate>
<DataTemplate DataType="{x:Type Implementations:PumpDesignViewModel}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\City.png" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</DataTemplate>
</TreeView.Resources>
</TreeView>
I have a standard WPF treeview and have bound items to view model classes.
I now wish to handle behaviour when items are double-clicked (opening documents visual-studio-style).
I can get event-handler to fire in the control housing the treeview (xaml shown), but how do I bind to specific behaviour on the view model classes - e.g. ProjectViewModel?
Preferable bound to ICommand-implementer, as this is used elsewhere...
Thanks for any comments,
Anders, Denmark
<TreeView ItemsSource="{Binding Projects}" MouseDoubleClick="TreeView_MouseDoubleClick">
<TreeView.ItemContainerStyle>
<!--
This Style binds a TreeViewItem to a TreeViewItemViewModel.
-->
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight" Value="Normal" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type Implementations:ProjectViewModel}" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\Region.png" />
<TextBlock Text="{Binding DisplayName}" />
</StackPanel>
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type Implementations:PumpViewModel}" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\State.png" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</HierarchicalDataTemplate>
<DataTemplate DataType="{x:Type Implementations:PumpDesignViewModel}">
<StackPanel Orientation="Horizontal">
<Image Width="16" Height="16" Margin="3,0" Source="Images\City.png" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</DataTemplate>
</TreeView.Resources>
</TreeView>
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对于标题问题:是的。主视图的虚拟机应显示 AboutBox。
但消息正文似乎有所不同,也许您可以扩展一下?
To the Title-question: Yes. The VM of the Main View should show the AboutBox.
But the body of the message seems different, maybe you can expand on it a little?
执行此操作的首选方法是使用您已经提到的命令模式。
即通过依赖属性绑定到 ICommand 实现。
依赖属性实际上是由静态支持属性实现的,该属性实现了框架使用的依赖内容。
不幸的是,MS 决定实现支持属性的方式至少可以说不是最佳的。
它通过硬编码字符串连接到您在 xaml 中绑定的公共非静态属性...
我不记得在哪里,但我发现了一个非常优雅的静态/非静态关系解决方案,它使用一个 lambda 表达式来进行映射,从而完全消除了硬编码、容易出错的字符串映射。
如果您仍然需要它,我可以向您发送更多有关此的信息。您知道在哪里联系我:-)
您需要解决的另一个问题是抽象视图的实现以保持可测试性。
The preferred way to do this is to use the command pattern as you already mentionend.
I.e. to bind to an ICommand implementation via a dependency property.
Dependency properties are actually implemented by a static backing property which implements the dependency stuff used by the framework.
Unfortunately the way MS decided to implement the backing property is - well, not optimal to say the least.
It is hooked up to the public, non-static property you bind to in xaml - by means of a hardcoded string...
I don't remember where but I found a quite elegant solution to the static/non-static relationship which uses a lambda expression to do the mapping thus completely removing the hardcoded, error prone string mapping.
If you still need it I can send you some more info on this. You know where to reach me :-)
Another concern you will need to adress is to abstract away the implementation of the view to maintain testability.