19. Implementation of MVVM architecture based on WPF event to command

Preface ：MVVM Use in development mode Command It's very convenient , But many controls do not Command, such as Text Focus of attention 、 Loss of focus, etc , Are directly related to... Through events View Background program interaction . At this time, if you still want to ViewModel Realization Command function , You need something else .

Be clear ,Microsoft.Expression.Interactions and System.Windows.Interactivity Assembly at Blend Only in tools , however , I don't know when to start , These two assemblies are deprecated , Now change to Microsoft.Xaml.Behaviors 了 .

One 、System.Windows.Interactivity

You can see it , Rely on the Framwork The minimum version is 4.0, Is the highest 4.8, And only support  .NETFramwork edition .

1.1 brief introduction

If the target framework is .NETFramwork The various versions of , such as 4,4.8 Equal Edition , Need to introduce System.Windows.Interactivity.dll Dynamic library , It can also be done through NuGet Download , It's just , This library , Now the update has stopped , But it can still be used after downloading . The officially recommended alternative library is another library Microsoft.Xaml.Behaviors.

If the target framework is .NET Core And above , It can also be used. , Only there will be a prompt to use .NETFramwork Restore this library in other versions of .

1.2 Use  

xaml Reference namespace in , There are two ways , Some versions may not work , The author here aims to frame .NETFramwork4.8 and .NET5 To test , It's all right .

xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

<TextBox Text="fengxiong" VerticalAlignment="Center">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="LostFocus">
            <i:InvokeCommandAction Command="{Binding OpenSerialPortCommand}"/>
        </i:EventTrigger>
        <i:EventTrigger EventName="GotFocus">
            <i:InvokeCommandAction Command="{Binding OpenSerialPortCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</TextBox>

here Interaction There are two choices , One is Triggers, The other is Behaviors, The author searched the relevant literature on the Internet , I found that some people said they used Behaviors, In fact, it is still used Triggers.

Two 、Microsoft.Xaml.Behaviors

2.1 brief introduction

The information found on the Internet by the author shows that , The first version is from 2018 year 12 month 3 Started on .

and  System.Windows.Interactivity.WPF Stop yes 2013 year 3 month 10 Number , And there is only one version .

On the official website System.Windows.Interactivity The creation display time is 2017 year 10 month 11

Microsoft.Xaml.Behaviors The relevant information is as follows .

2.2 Use

and System.Windows.Interactivity The way to use it is the same , Just changed the namespace . Download first and then reference .

 xmlns:i="http://schemas.microsoft.com/xaml/behaviors"

<TextBox Text="fengxiong" VerticalAlignment="Center">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="LostFocus">
            <i:InvokeCommandAction Command="{Binding OpenSerialPortCommand}"/>
        </i:EventTrigger>
        <i:EventTrigger EventName="GotFocus">
            <i:InvokeCommandAction Command="{Binding OpenSerialPortCommand}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</TextBox>

3、 ... and 、 Citations

3.1 .Net Core 3 : About WPF in System.Windows.Interactivity The problem of migration - ZDY ' LOVE | About photography 、 travel 、 outdoors 、 travel 、 strategy 、 feeling 、 Programming ...

3.2 System.Windows.Interactivity Namespace | Microsoft Docs 

3.3 Search | Microsoft Docs 

3.4 WPF in System.Windows.Interactivity Use _lpb914 The blog of -CSDN Blog  

3.5 NuGet Gallery | Microsoft.Xaml.Behaviors.Wpf 1.1.39 

3.6 NuGet Gallery | System.Windows.Interactivity.WPF 2.0.20525