Add file and text drop behaviors

samples/BehaviorsTestApplication/ViewModels/MainWindowViewModel.cs

@@ -12,7 +12,7 @@
 {
     private int _value;
 
     public MainWindowViewModel()
     {
         PointerTriggersViewModel = new PointerTriggersViewModel();
 
@@ -85,9 +85,9 @@
 
         OpenItemCommand = ReactiveCommand.Create<ItemViewModel>(OpenItem);
 
-        OpenFilesCommand = ReactiveCommand.Create<IReadOnlyList<IStorageFile>>(OpenFiles);
+        OpenFilesCommand = ReactiveCommand.Create<IEnumerable<IStorageItem>>(OpenFiles);
         SaveFileCommand = ReactiveCommand.Create<Uri>(SaveFile);
-        OpenFoldersCommand = ReactiveCommand.Create<IReadOnlyList<IStorageFolder>>(OpenFolders);
+        OpenFoldersCommand = ReactiveCommand.Create<IEnumerable<IStorageFolder>>(OpenFolders);
 
         GetClipboardTextCommand = ReactiveCommand.Create<string?>(GetClipboardText);
     }
@@ -152,13 +152,13 @@
         Console.WriteLine($"OpenItemCommand: {item.Value}");
     }
 
-    private void OpenFiles(IReadOnlyList<IStorageFile> files)
+    private void OpenFiles(IEnumerable<IStorageItem> files)
     {
         foreach (var file in files)
         {
             Console.WriteLine($"OpenFilesCommand: {file.Name}, {file.Path}");
 
             FileItems.Add(file.Path);
         }
     }
 
@@ -166,16 +166,16 @@
     {
         Console.WriteLine($"SaveFileCommand: {file}");
 
         FileItems.Add(file);
     }
 
-    private void OpenFolders(IReadOnlyList<IStorageFolder> folders)
+    private void OpenFolders(IEnumerable<IStorageFolder> folders)
     {
         foreach (var folder in folders)
         {
             Console.WriteLine($"OpenFoldersCommand: {folder.Name}, {folder.Path}");
 
             FileItems.Add(folder.Path);
         }
     }
 

samples/BehaviorsTestApplication/Views/Pages/FileDropHandlerView.axaml

@@ -21,6 +21,18 @@
       </Interaction.Behaviors>
       <TextBlock Text="Drop files here" HorizontalAlignment="Center" VerticalAlignment="Center" />
     </Border>
+    <Border Background="Transparent" Padding="20" BorderThickness="1" BorderBrush="{DynamicResource SystemAccentColor}">
+      <Interaction.Behaviors>
+        <FilesDropBehavior Command="{Binding OpenFilesCommand}" />
+      </Interaction.Behaviors>
+      <TextBlock Text="Drop files here" HorizontalAlignment="Center" VerticalAlignment="Center" />
+    </Border>
+    <Border Background="Transparent" Padding="20" BorderThickness="1" BorderBrush="{DynamicResource SystemAccentColor}">
+      <Interaction.Behaviors>
+        <TextDropBehavior Command="{Binding GetClipboardTextCommand}" />
+      </Interaction.Behaviors>
+      <TextBlock Text="Drop text here" HorizontalAlignment="Center" VerticalAlignment="Center" />
+    </Border>
     <ListBox ItemsSource="{Binding FileItems}" />
   </StackPanel>
 </UserControl>

src/Avalonia.Xaml.Interactions.DragAndDrop/Avalonia.Xaml.Interactions.DragAndDrop.csproj

@@ -22,6 +22,7 @@
   <Import Project="..\..\build\TrimmingEnable.targets" />
 
   <ItemGroup>
+    <ProjectReference Include="..\Avalonia.Xaml.Interactions\Avalonia.Xaml.Interactions.csproj" />
     <ProjectReference Include="..\Avalonia.Xaml.Interactivity\Avalonia.Xaml.Interactivity.csproj" />
   </ItemGroup>
 

src/Avalonia.Xaml.Interactions.DragAndDrop/DropBehaviorBase.cs

@@ -0,0 +1,88 @@
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.Xaml.Interactions.Core;
+
+namespace Avalonia.Xaml.Interactions.DragAndDrop;
+
+/// <summary>
+/// 
+/// </summary>
+public abstract class DropBehaviorBase : InvokeCommandBehaviorBase
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    protected IDropHandler? Handler { get; set; }
+
+    /// <inheritdoc />
+    protected override void OnAttachedToVisualTree()
+    {
+        if (AssociatedObject is not null)
+        {
+            DragDrop.SetAllowDrop(AssociatedObject, true);
+        }
+        AssociatedObject?.AddHandler(DragDrop.DragEnterEvent, DragEnter);
+        AssociatedObject?.AddHandler(DragDrop.DragLeaveEvent, DragLeave);
+        AssociatedObject?.AddHandler(DragDrop.DragOverEvent, DragOver);
+        AssociatedObject?.AddHandler(DragDrop.DropEvent, Drop);
+    }
+
+    /// <inheritdoc />
+    protected override void OnDetachedFromVisualTree()
+    {
+        if (AssociatedObject is not null)
+        {
+            DragDrop.SetAllowDrop(AssociatedObject, false);
+        }
+        AssociatedObject?.RemoveHandler(DragDrop.DragEnterEvent, DragEnter);
+        AssociatedObject?.RemoveHandler(DragDrop.DragLeaveEvent, DragLeave);
+        AssociatedObject?.RemoveHandler(DragDrop.DragOverEvent, DragOver);
+        AssociatedObject?.RemoveHandler(DragDrop.DropEvent, Drop);
+    }
+
+    private void DragEnter(object? sender, DragEventArgs e)
+    {
+        Handler?.Enter(sender, e, null, null);
+    }
+
+    private void DragLeave(object? sender, RoutedEventArgs e)
+    {
+        Handler?.Leave(sender, e);
+    }
+
+    private void DragOver(object? sender, DragEventArgs e)
+    {
+        Handler?.Over(sender, e, null, null);
+    }
+
+    private void Drop(object? sender, DragEventArgs e)
+    {
+        Handler?.Drop(sender, e, null, null);
+    }
+
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="parameter"></param>
+    protected void ExecuteCommand(object? parameter)
+    {
+        if (IsEnabled != true || Command is null)
+        {
+            return;
+        }
+
+        if (AssociatedObject is not { IsVisible: true, IsEnabled: true })
+        {
+            return;
+        }
+
+        var resolvedParameter = ResolveParameter(parameter);
+
+        if (Command?.CanExecute(resolvedParameter) != true)
+        {
+            return;
+        }
+
+        Command.Execute(resolvedParameter);
+    }
+}

src/Avalonia.Xaml.Interactions.DragAndDrop/FilesDropBehavior.cs

@@ -0,0 +1,43 @@
+using Avalonia.Input;
+
+namespace Avalonia.Xaml.Interactions.DragAndDrop;
+
+/// <summary>
+/// 
+/// </summary>
+public sealed class FilesDropBehavior : DropBehaviorBase
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public FilesDropBehavior()
+    {
+        Handler = new FilesDropHandler(ExecuteCommand);
+    }
+
+    private sealed class FilesDropHandler(System.Action<object?> execute) : DropHandlerBase
+    {
+        public override bool Validate(object? sender, DragEventArgs e, object? sourceContext, object? targetContext, object? state)
+        {
+            return e.Data.Contains(DataFormats.FileNames);
+        }
+
+        public override bool Execute(object? sender, DragEventArgs e, object? sourceContext, object? targetContext, object? state)
+        {
+            if (!e.Data.Contains(DataFormats.FileNames))
+            {
+                return false;
+            }
+
+            var files = e.Data.GetFiles();
+            if (files is null)
+            {
+                return false;
+            }
+
+            execute(files);
+
+            return true;
+        }
+    }
+}

src/Avalonia.Xaml.Interactions.DragAndDrop/TextDropBehavior.cs

@@ -0,0 +1,43 @@
+using Avalonia.Input;
+
+namespace Avalonia.Xaml.Interactions.DragAndDrop;
+
+/// <summary>
+/// 
+/// </summary>
+public sealed class TextDropBehavior : DropBehaviorBase
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public TextDropBehavior()
+    {
+        Handler = new FilesDropHandler(ExecuteCommand);
+    }
+
+    private sealed class FilesDropHandler(System.Action<object?> execute) : DropHandlerBase
+    {
+        public override bool Validate(object? sender, DragEventArgs e, object? sourceContext, object? targetContext, object? state)
+        {
+            return e.Data.Contains(DataFormats.Text);
+        }
+
+        public override bool Execute(object? sender, DragEventArgs e, object? sourceContext, object? targetContext, object? state)
+        {
+            if (!e.Data.Contains(DataFormats.Text))
+            {
+                return false;
+            }
+
+            var text = e.Data.GetText();
+            if (text is null)
+            {
+                return false;
+            }
+
+            execute(text);
+
+            return true;
+        }
+    }
+}

src/Avalonia.Xaml.Interactions/ExecuteCommand/InvokeCommandBehaviorBase.cs

@@ -1,4 +1,5 @@
 using System.Windows.Input;
+using Avalonia.Controls;
 using Avalonia.Data.Converters;
 using Avalonia.Xaml.Interactivity;
 
@@ -7,7 +8,7 @@ namespace Avalonia.Xaml.Interactions.Core;
 /// <summary>
 /// Invoke command behavior base class.
 /// </summary>
-public abstract class InvokeCommandBehaviorBase : StyledElementBehavior
+public abstract class InvokeCommandBehaviorBase : StyledElementBehavior<Control>
 {
     /// <summary>
     /// Identifies the <seealso cref="Command"/> avalonia property.