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wpf之Interaction.Triggers

news 2025/10/14 10:52:44

前言

在wpf中 Interaction.Triggers是对命令的补充，命令能应用的场合有限，比如Button的单击事件，但是像window窗体的Loaded事件，TextBox的TextChanged就无法使用命令。Interaction.Triggers的结构如下：

<控件><i:Interaction.Triggers><触发器类型><动作类型 属性="值"/></触发器类型></i:Interaction.Triggers>
</控件>

1、引用dll

在NuGet包管理器中选择Microsoft.Xaml.Behaviors.Wpf这个包安装
在这里插入图片描述

2、引用命名空间

在xaml代码中加上如下代码

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

3、window的Loaded事件

下面的代码中EventName指定了需要绑定的事件的名称，这里是”Loaded“事件。在InvokeCommandAction的Command属性中绑定事件CommandWindowLoaded，这里的CommandWindowLoaded在ViewModel类中定义和实例化。

<Window x:Class="wpf之Interaction.Triggers.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:local="clr-namespace:wpf之Interaction.Triggers"xmlns:Event="http://schemas.microsoft.com/xaml/behaviors"mc:Ignorable="d"Title="MainWindow" Height="450" Width="800"><Event:Interaction.Triggers><Event:EventTrigger EventName="Loaded"><Event:InvokeCommandAction Command="{Binding CommandWindowLoaded}"/></Event:EventTrigger></Event:Interaction.Triggers><Grid></Grid>
</Window>

自定义命令DelegateCommand

public class DelegateCommand : ICommand{private readonly Action<object> _execute;private readonly Func<object, bool> _canExecute;public DelegateCommand(Action<object> execute, Func<object, bool> canExecute = null){_execute = execute ?? throw new ArgumentNullException(nameof(execute));_canExecute = canExecute;}public bool CanExecute(object parameter){if (_canExecute != null){return _canExecute(parameter);}else{return true;}}public void Execute(object parameter){_execute(parameter);}public event EventHandler CanExecuteChanged{add => CommandManager.RequerySuggested += value;remove => CommandManager.RequerySuggested -= value;}}

定义ViewMode的基类ViewModelBase

 public class ViewModelBase : INotifyPropertyChanged{public event PropertyChangedEventHandler PropertyChanged;public void OnPropertyChanged(string propname){if (PropertyChanged != null){PropertyChanged(this, new PropertyChangedEventArgs(propname));}}}

定义ViewMode并且继承ViewModelBase，在ViewMode中实例化一个命令，

 public class ViewModel : ViewModelBase{public ICommand CommandWindowLoaded { get; set; }public ViewModel(){CommandWindowLoaded = new DelegateCommand(WindowLoaded);}public void WindowLoaded(object param){Console.WriteLine("窗体加载");}}

4、TextBox的TextChanged事件

当你改变TextBox内容的时候，不停的就会触发TextChangedCommand命令执行。
在这里插入图片描述

下面的代码同样是通过EventName指定需要绑定的事件类型，通过Command属性来绑定ViewModel中具体的事件，同时还可以传递参数。

<Window x:Class="wpf之Interaction.Triggers.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:local="clr-namespace:wpf之Interaction.Triggers"xmlns:Event="http://schemas.microsoft.com/xaml/behaviors"mc:Ignorable="d"Title="MainWindow" Height="450" Width="800"><Event:Interaction.Triggers><Event:EventTrigger EventName="Loaded"><Event:InvokeCommandAction Command="{Binding CommandWindowLoaded}"/></Event:EventTrigger></Event:Interaction.Triggers><Grid><StackPanel ><TextBox x:Name="tbx_test" Height="20" Width=" 40"><Event:Interaction.Triggers><Event:EventTrigger EventName="TextChanged"><Event:InvokeCommandAction Command="{Binding TextChangedCommand}" CommandParameter="{Binding Path=Text,ElementName=tbx_test}"/></Event:EventTrigger></Event:Interaction.Triggers></TextBox ></StackPanel ></Grid>
</Window>

 public class ViewModel : ViewModelBase{public ICommand CommandWindowLoaded { get; set; }public ICommand TextChangedCommand { get; set; }public ViewModel(){CommandWindowLoaded = new DelegateCommand(WindowLoaded);TextChangedCommand= new DelegateCommand(TextChange);}public void WindowLoaded(object param){Console.WriteLine("窗体加载");}public void TextChange(object param){Console.WriteLine($"文本修改{param}");}}