本系列文章导航
- https://www.cnblogs.com/aierong/category/2297596.html
0.说明
CommunityToolkit.Mvvm8.1有一个重大更新的功能:源生成器功能,它极大简化我们的mvvm代码
但是本篇先总结一下原写法,下篇再总结源生成器功能
1.模型定义
必须继承:ObservableObject
2.viewmodel代码实现
几个关键点:
SetProperty是给属性赋值,并且通知更改通知
ButtonClickCommand.NotifyCanExecuteChanged(); //通知命令 已经改变
RelayCommand ButtonClickCommand //定义命令
namespace WpfDemoNet6.Demo
{
public class DataViewModel1 : ObservableObject
{
private string title = "hello";
public string Title
{
get
{
return title;
}
set
{
//title = value;
//PropertyChanged?.Invoke( this , new PropertyChangedEventArgs( "Name" ) );
//SetProperty 相当与设置值,并且PropertyChanged通知调用
SetProperty( ref title , value );
}
}
private bool isEnabled = false;
/// <summary>
/// 是否可以使用
/// </summary>
public bool IsEnabled
{
get => isEnabled;
set
{
SetProperty( ref isEnabled , value );
//通知命令 已经改变
ButtonClickCommand.NotifyCanExecuteChanged();
}
}
/// <summary>
/// 命令
/// </summary>
public RelayCommand ButtonClickCommand
{
get;
}
public DataViewModel1 ()
{
//RelayCommand的第一个参数是命令调用语句
// 第2个参数(可选)是否允许使用
ButtonClickCommand = new RelayCommand( () =>
{
//点击按钮,修改标题
Title = "hello(改)";
} , () =>
{
return IsEnabled;
} );
ButtonClickCommandPar = new RelayCommand<double>( ( double val ) =>
{
Title = $"hello(改):{val}";
} );
}
public RelayCommand<double> ButtonClickCommandPar
{
get;
}
}
}3.异步命令
异步命令会自动控制控件的可见性,并且提供一个IsRunning属性可以判断异步是否完成
public DataViewModel1 ()
{
AsyncButtonClickCommand = new AsyncRelayCommand( RunTxtAsync );
AsyncButtonParClickCommand = new AsyncRelayCommand<double>( RunTxtParAsync );
}
/*
特别说明：异步命令会自动控制控件的可见性,并且提供一个IsRunning属性可以判断异步是否完成
*/
/// <summary>
/// 命令
/// </summary>
public IAsyncRelayCommand AsyncButtonClickCommand
{
get;
}
private async Task RunTxtAsync ()
{
await Task.Delay( 4800 );
Title = "hello(Task改)";
}
/// <summary>
/// 命令(带参数的)
/// </summary>
public IAsyncRelayCommand<double> AsyncButtonParClickCommand
{
get;
}
private async Task RunTxtParAsync ( double val )
{
await Task.Delay( 4800 );
Title = $"hello(Task改):{val}";
}<!--
特别说明：异步命令会自动控制控件的可见性,并且提供一个IsRunning属性可以判断异步是否完成
-->
<Button Width="100"
Height="30"
Command="{Binding AsyncButtonClickCommand}"
Content="异步" />
<TextBlock HorizontalAlignment="Center"
FontSize="20"
FontStyle="Italic"
FontWeight="Bold"
Foreground="Green"
Text="loading......"
Visibility="{Binding AsyncButtonClickCommand.IsRunning, Converter={StaticResource myboolconvert}}" />
