[Avalonia.Native] Use relative placement for detecting drag and drop locations. (#20280)

* Use relative position of view for drag and drop

* Add Drag And Drop Test

* Add AutomationProperties

native/Avalonia.Native/src/OSX/AvnView.mm

@@ -854,9 +854,10 @@ static void ConvertTilt(NSPoint tilt, float* xTilt, float* yTilt)
 
 - (NSDragOperation)triggerAvnDragEvent: (AvnDragEventType) type info: (id <NSDraggingInfo>)info
 {
-    auto localPoint = [self convertPoint:[info draggingLocation] toView:self];
+    NSPoint eventLocation = [info draggingLocation];
-    auto avnPoint = ToAvnPoint(localPoint);
+    auto viewLocation = [self convertPoint:NSMakePoint(0, 0) toView:nil];
-    auto point = [self translateLocalPoint:avnPoint];
+    auto localPoint = NSMakePoint(eventLocation.x - viewLocation.x, viewLocation.y - eventLocation.y);
+    auto point = ToAvnPoint(localPoint);
     auto modifiers = [self getModifiers:[[NSApp currentEvent] modifierFlags]];
     NSDragOperation nsop = [info draggingSourceOperationMask];
 

samples/IntegrationTestApp/MainWindow.axaml.cs

@@ -82,6 +82,7 @@ namespace IntegrationTestApp
                 new("ComboBox", () => new ComboBoxPage()),
                 new("ContextMenu", () => new ContextMenuPage()),
                 new("DesktopPage", () => new DesktopPage()),
+                new("DragDrop", () => new DragDropPage()),
                 new("Embedding", () => new EmbeddingPage()),
                 new("Gestures", () => new GesturesPage()),
                 new("ListBox", () => new ListBoxPage()),

samples/IntegrationTestApp/Pages/DragDropPage.axaml

@@ -0,0 +1,62 @@
+<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"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="IntegrationTestApp.Pages.DragDropPage">
+  <DockPanel>
+    <StackPanel DockPanel.Dock="Top" Orientation="Horizontal" Margin="4">
+      <Button Name="ResetDragDrop" Click="ResetDragDrop_Click" Margin="0,0,8,0">Reset</Button>
+      <TextBlock VerticalAlignment="Center">Drop Position: </TextBlock>
+      <TextBlock Name="DropPosition" VerticalAlignment="Center" Margin="4,0"/>
+      <TextBlock VerticalAlignment="Center" Margin="8,0,0,0">Status: </TextBlock>
+      <TextBlock Name="DragDropStatus" VerticalAlignment="Center" Margin="4,0"/>
+    </StackPanel>
+
+    <!-- Use a Grid with row definitions to create offset from window origin -->
+    <!-- The top spacer ensures the drag/drop controls are NOT at (0,0) -->
+    <Grid RowDefinitions="100,*">
+      <!-- Spacer row to offset controls from window origin -->
+      <Border Grid.Row="0" Background="LightGray">
+        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center"
+                   Text="Spacer (100px) - Controls below are offset from window origin"/>
+      </Border>
+
+      <!-- Drag and Drop test area -->
+      <Grid Grid.Row="1" ColumnDefinitions="*,*" Margin="20">
+        <!-- Drag Source -->
+        <Border Name="DragSource"
+                Grid.Column="0"
+                Background="CornflowerBlue"
+                Margin="10"
+                CornerRadius="8"
+                AutomationProperties.AccessibilityView="Content"
+                PointerPressed="DragSource_PointerPressed">
+          <TextBlock HorizontalAlignment="Center"
+                     VerticalAlignment="Center"
+                     Text="Drag Source"
+                     Foreground="White"
+                     FontWeight="Bold"/>
+        </Border>
+
+        <!-- Drop Target -->
+        <Border Name="DropTarget"
+                Grid.Column="1"
+                Background="LightGreen"
+                Margin="10"
+                CornerRadius="8"
+                AutomationProperties.AccessibilityView="Content"
+                DragDrop.AllowDrop="True">
+          <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
+            <TextBlock Text="Drop Target"
+                       HorizontalAlignment="Center"
+                       FontWeight="Bold"/>
+            <TextBlock Name="DropTargetText"
+                       HorizontalAlignment="Center"
+                       Text="Drop items here"/>
+          </StackPanel>
+        </Border>
+      </Grid>
+    </Grid>
+  </DockPanel>
+</UserControl>

samples/IntegrationTestApp/Pages/DragDropPage.axaml.cs

@@ -0,0 +1,103 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Input.Platform;
+using Avalonia.Interactivity;
+
+namespace IntegrationTestApp.Pages;
+
+public partial class DragDropPage : UserControl
+{
+    public DragDropPage()
+    {
+        InitializeComponent();
+
+        // Set up drag-drop event handlers
+        AddHandler(DragDrop.DragOverEvent, DropTarget_DragOver);
+        AddHandler(DragDrop.DropEvent, DropTarget_Drop);
+    }
+
+    private async void DragSource_PointerPressed(object? sender, PointerPressedEventArgs e)
+    {
+        if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
+        {
+            var dragData = new DataTransfer();
+            dragData.Add(DataTransferItem.CreateText("TestDragData"));
+
+            DragDropStatus.Text = "Dragging...";
+
+            var result = await DragDrop.DoDragDropAsync(e, dragData, DragDropEffects.Copy | DragDropEffects.Move);
+
+            DragDropStatus.Text = result switch
+            {
+                DragDropEffects.Copy => "Copied",
+                DragDropEffects.Move => "Moved",
+                DragDropEffects.None => "Cancelled",
+                _ => $"Result: {result}"
+            };
+        }
+    }
+
+    private void DropTarget_DragOver(object? sender, DragEventArgs e)
+    {
+        // Only handle events for the drop target
+        if (e.Source != DropTarget && !IsChildOf(e.Source as Visual, DropTarget))
+            return;
+
+        e.DragEffects = DragDropEffects.Copy;
+
+        // Get the position relative to the drop target
+        var position = e.GetPosition(DropTarget);
+        DropPosition.Text = $"DragOver: ({position.X:F0}, {position.Y:F0})";
+    }
+
+    private void DropTarget_Drop(object? sender, DragEventArgs e)
+    {
+        // Only handle events for the drop target
+        if (e.Source != DropTarget && !IsChildOf(e.Source as Visual, DropTarget))
+            return;
+
+        // Get the position relative to the drop target
+        var position = e.GetPosition(DropTarget);
+        DropPosition.Text = $"Drop: ({position.X:F0}, {position.Y:F0})";
+
+        // Check if the position is within reasonable bounds of the drop target
+        var bounds = DropTarget.Bounds;
+        var isWithinBounds = position.X >= 0 && position.X <= bounds.Width &&
+                             position.Y >= 0 && position.Y <= bounds.Height;
+
+        var text = e.DataTransfer.TryGetText();
+        if (text != null)
+        {
+            DropTargetText.Text = isWithinBounds
+                ? $"Dropped: {text} at ({position.X:F0}, {position.Y:F0})"
+                : $"ERROR: Position out of bounds! ({position.X:F0}, {position.Y:F0})";
+            DragDropStatus.Text = isWithinBounds ? "Drop OK" : "Drop position ERROR";
+        }
+
+        e.DragEffects = DragDropEffects.Copy;
+    }
+
+    private static bool IsChildOf(Visual? child, Visual? parent)
+    {
+        if (child == null || parent == null)
+            return false;
+
+        var current = child.Parent as Visual;
+        while (current != null)
+        {
+            if (current == parent)
+                return true;
+            current = current.Parent as Visual;
+        }
+        return false;
+    }
+
+    private void ResetDragDrop_Click(object? sender, RoutedEventArgs e)
+    {
+        DropPosition.Text = string.Empty;
+        DragDropStatus.Text = string.Empty;
+        DropTargetText.Text = "Drop items here";
+    }
+}

tests/Avalonia.IntegrationTests.Appium/DragDropTests.cs

@@ -0,0 +1,117 @@
+using System;
+using System.Threading;
+using OpenQA.Selenium.Appium;
+using OpenQA.Selenium.Interactions;
+using Xunit;
+
+namespace Avalonia.IntegrationTests.Appium;
+
+[Collection("Default")]
+public class DragDropTests : TestBase
+{
+    public DragDropTests(DefaultAppFixture fixture)
+        : base(fixture, "DragDrop")
+    {
+        var reset = Session.FindElementByAccessibilityId("ResetDragDrop");
+        reset.Click();
+    }
+
+    [PlatformFact(TestPlatforms.MacOS)]
+    public void DragDrop_Coordinates_Correct_When_Controls_Offset_From_Origin()
+    {
+        // This test verifies the fix for drag-drop coordinate calculation when
+        // controls are positioned away from the window origin.
+        // Issue: In embedded views or when controls have margin/offset from origin,
+        // the drag-drop coordinates were incorrectly calculated relative to the
+        // window rather than the view.
+
+        var dragSource = Session.FindElementByAccessibilityId("DragSource");
+        var dropTarget = Session.FindElementByAccessibilityId("DropTarget");
+        var dropPosition = Session.FindElementByAccessibilityId("DropPosition");
+        var dragDropStatus = Session.FindElementByAccessibilityId("DragDropStatus");
+
+        // Perform drag from source to target
+        new Actions(Session)
+            .MoveToElement(dragSource)
+            .ClickAndHold()
+            .MoveToElement(dropTarget)
+            .Release()
+            .Perform();
+
+        Thread.Sleep(500); // Allow UI to update
+
+        // Verify the drop was successful
+        var status = dragDropStatus.Text;
+        Assert.True(status == "Drop OK" || status == "Copied",
+            $"Expected drop to succeed, but status was: {status}");
+
+        // Verify the drop position is within the target bounds
+        // If the coordinate calculation bug exists, the position would be
+        // offset by the spacer/margin and would show negative coordinates
+        // or coordinates outside the target bounds
+        var positionText = dropPosition.Text;
+        Assert.StartsWith("Drop:", positionText, StringComparison.Ordinal);
+
+        // The DropTargetText should not contain "ERROR"
+        var dropTargetText = Session.FindElementByAccessibilityId("DropTargetText");
+        Assert.DoesNotContain("ERROR", dropTargetText.Text);
+    }
+
+    [PlatformFact(TestPlatforms.MacOS)]
+    public void DragDrop_Position_Updates_During_DragOver()
+    {
+        // Verifies that position is correctly reported during drag-over events
+        var dragSource = Session.FindElementByAccessibilityId("DragSource");
+        var dropTarget = Session.FindElementByAccessibilityId("DropTarget");
+        var dropPosition = Session.FindElementByAccessibilityId("DropPosition");
+
+        // Start drag and move over target, then release
+        var device = new PointerInputDevice(PointerKind.Mouse);
+        var builder = new ActionBuilder();
+
+        // Move to drag source and start drag
+        builder.AddAction(device.CreatePointerMove(dragSource, 0, 0, TimeSpan.FromMilliseconds(100)));
+        builder.AddAction(device.CreatePointerDown(MouseButton.Left));
+
+        // Move to drop target (this triggers DragOver events)
+        builder.AddAction(device.CreatePointerMove(dropTarget, 0, 0, TimeSpan.FromMilliseconds(200)));
+
+        // Pause to allow DragOver events to be processed
+        builder.AddAction(device.CreatePause(TimeSpan.FromMilliseconds(200)));
+
+        // Release at current position (completes the drag)
+        builder.AddAction(device.CreatePointerUp(MouseButton.Left));
+
+        Session.PerformActions(builder.ToActionSequenceList());
+
+        Thread.Sleep(200);
+
+        // Check that position was recorded (either DragOver or Drop)
+        var positionText = dropPosition.Text;
+
+        // Position should have been updated during drag-over or drop
+        Assert.True(positionText.Contains("DragOver:") || positionText.Contains("Drop:"),
+            $"Expected position to be updated during drag, but got: {positionText}");
+    }
+
+    [Fact]
+    public void DragDrop_Can_Be_Cancelled()
+    {
+        var dragSource = Session.FindElementByAccessibilityId("DragSource");
+        var dragDropStatus = Session.FindElementByAccessibilityId("DragDropStatus");
+
+        // Start drag but release outside any drop target
+        new Actions(Session)
+            .MoveToElement(dragSource)
+            .ClickAndHold()
+            .MoveByOffset(-200, 0) // Move away from drop target
+            .Release()
+            .Perform();
+
+        Thread.Sleep(500);
+
+        // Status should indicate cancelled
+        var status = dragDropStatus.Text;
+        Assert.Equal("Cancelled", status);
+    }
+}