[Feature] RoutedCommand

[workgroupengineering]

Experimenta implemtation of RoutedCommand like WPF.

the currently supported flow is this:

sequenceDiagram
    participant RotendCommand
    participant View
    participant RoutedCommandsManager
    participant ViewModel
    participant TopLevel
    TopLevel->>RoutedCommandsManager: Got Focus
    RoutedCommandsManager->>RotendCommand: Raise CanExecuteChanged
    RotendCommand->>View: Raise RoutedCommandsManager.CanExecuteEvent
    View->>RoutedCommandsManager: Raise RoutedCommandsManager.CanExecuteEvent
    RoutedCommandsManager->>ViewModel: ICommand.CanExecute
    RoutedCommandsManager->>RotendCommand: Handle=True
    RotendCommand->>View: Raise RoutedCommandsManager.ExecuteEvent
    View->>RoutedCommandsManager: Raise RoutedCommandsManager.ExecuteEvent
    RoutedCommandsManager->>ViewModel: ICommand.Execute

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Get Started

1. Install package

   dotnet add package package Avalonia.Labs.RoutedCommand

2. Add XML Namespace

   <UserControl xmlns="https://github.com/avaloniaui"
               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:lab="clr-namespace:Avalonia.Labs.Catalog"
   +             xmlns:rc="clr-namespace:Avalonia.Labs.Input;assembly=Avalonia.Labs.RoutedCommand"
               mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
               xmlns:viewModels="clr-namespace:Avalonia.Labs.Catalog.ViewModels"
               x:Class="Avalonia.Labs.Catalog.Views.RouteCommandView"
               x:DataType="viewModels:RouteCommandViewModel"
               HorizontalContentAlignment="Stretch"
               VerticalContentAlignment="Stretch"
               >
               ...
   </UserControl>
   

3. Define your's RouterCommands

   public static class ApplicationCommands
   {
       public readonly static RoutedCommand Open = new RoutedCommand(nameof(Open));
       public readonly static RoutedCommand Save = new RoutedCommand(nameof(Save));
   }

4. Assing your RotedCommand

           <UniformGrid Columns="2"
                       Grid.Column="2">
               <Button Content="Open"
                       Command="{x:Static lab:ApplicationCommands.Open}"
                       CommandParameter="{Binding .}"/>
               <Button Content="Save"
                       Command="{x:Static lab:ApplicationCommands.Save}"
                       CommandParameter="{Binding .}"/>
           </UniformGrid>

5. Binding RouterCommand to your's ViewModel

   <UserControl xmlns="https://github.com/avaloniaui"
               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:lab="clr-namespace:Avalonia.Labs.Catalog"
               xmlns:rc="clr-namespace:Avalonia.Labs.Input;assembly=Avalonia.Labs.RoutedCommand"
               mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
               xmlns:viewModels="clr-namespace:Avalonia.Labs.Catalog.ViewModels"
               x:Class="Avalonia.Labs.Catalog.Views.RouteCommandView"
               x:DataType="viewModels:RouteCommandViewModel"
               HorizontalContentAlignment="Stretch"
               VerticalContentAlignment="Stretch"
               >
   <rc:RoutedCommandsManager.Commands>
       <rc:RoutedCommandBinding RoutedCommand="{x:Static lab:ApplicationCommands.Open}" Command="{Binding Open}" />
       <rc:RoutedCommandBinding RoutedCommand="{x:Static lab:ApplicationCommands.Save}" Command="{Binding Save}" />
   </rc:RoutedCommandsManager.Commands>
   ...
   </UserControl>

Todo

• KeyBinding
• CommandTarget (requires modification in Avalonia).

[maxkatz6]

Shouldn't it be public and named RequerySuggested?
Similarly to https://github.com/dotnet/wpf/blob/main/src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Input/Command/CommandManager.cs#L38

[maxkatz6]

Added this event

[maxkatz6]

WPF CommandBinding is a bit different, where you set original ICommand and has CanExecute + Executed events.
It can be confusing when porting code from WPF, as in this PR RoutedCommandBinding.Command is actually target command, that gets executed.

[maxkatz6]

Renamed Command to ExecutingCommand