[Android] Fix single taps

src/Controls/samples/Controls.Sample.UITests/Elements/DoubleTapGallery.cs

@@ -0,0 +1,35 @@
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample
+{
+	public class DoubleTapGallery : Microsoft.Maui.Controls.ContentView
+	{
+		public DoubleTapGallery()
+		{
+			AutomationId = "DoubleTapGallery";
+
+			var layout = new VerticalStackLayout() { Margin = 10, Spacing = 10 };
+
+			var result = new Label() { AutomationId = "DoubleTapResults" };
+
+			var tapSurface = new Grid()
+			{
+				HeightRequest = 200,
+				WidthRequest = 200,
+				BackgroundColor = Microsoft.Maui.Graphics.Colors.AliceBlue,
+				AutomationId = "DoubleTapSurface"
+			};
+
+			var doubleTapRecognizer = new TapGestureRecognizer() { NumberOfTapsRequired = 2 };
+			doubleTapRecognizer.Tapped += (sender, args) => { result.Text = "Success"; };
+
+			tapSurface.GestureRecognizers.Add(doubleTapRecognizer);
+
+			layout.Add(tapSurface);
+			layout.Add(result);
+
+			Content = layout;
+		}
+	}
+}
+

src/Controls/samples/Controls.Sample.UITests/Elements/GestureRecognizerGallery.cs

@@ -1,4 +1,6 @@
-using Microsoft.Maui.Controls.Internals;
+using System.Drawing;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Internals;
 
 namespace Maui.Controls.Sample
 {
@@ -8,6 +10,7 @@ public class GestureRecognizerGallery : ContentViewGalleryPage
 		public GestureRecognizerGallery()
 		{
 			Add(new PointerGestureRecognizerEvents());
+			Add(new DoubleTapGallery());
 		}
 	}
 }

src/Controls/samples/Controls.Sample.UITests/Issues/Issues16561.xaml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue16561">
+    <StackLayout>
+
+        <Grid x:Name="TapArea"
+              AutomationId="TapArea"
+              BackgroundColor="LightBlue"
+              Margin="10"
+              HeightRequest="300">
+            <Label HorizontalOptions="Center"
+                   VerticalOptions="Center"
+                   TextColor="Black"
+                   Text="Tap In This Grid" />
+        </Grid>
+
+        <Label HeightRequest="100"
+               AutomationId="Tap1Label"
+               Background="green"
+               x:Name="Tap1Label" />
+
+        <Label HeightRequest="100"
+               AutomationId="Tap2Label"
+               Background="green"
+               x:Name="Tap2Label" />
+
+    </StackLayout>
+</ContentPage>

src/Controls/samples/Controls.Sample.UITests/Issues/Issues16561.xaml.cs

@@ -0,0 +1,53 @@
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+using Microsoft.Maui.Platform;
+
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 16561, "Quick single taps on Android have wrong second tap location", PlatformAffected.Android)]
+	public partial class Issue16561 : ContentPage
+	{
+		int _taps;
+
+		public Issue16561()
+		{
+			InitializeComponent();
+
+			var tapGesture = new TapGestureRecognizer();
+			tapGesture.Tapped += TapHandler;
+
+			TapArea.GestureRecognizers.Add(tapGesture);
+		}
+
+		void TapHandler(object sender, TappedEventArgs e)
+		{
+			var pos = e.GetPosition(TapArea);
+
+			if (pos == null)
+			{
+				Tap1Label.Text = $"Error, could not get tap position";
+				return;
+			}
+
+#if ANDROID
+			// Adjust the results for display density, so they make sense to the 
+			// Appium test consuming this.
+			var x = this.Handler.MauiContext.Context.ToPixels(pos.Value.X);
+			var y = this.Handler.MauiContext.Context.ToPixels(pos.Value.Y);
+			pos = new(x, y);
+#endif
+
+			if (_taps % 2 == 0)
+			{
+				Tap1Label.Text = $"{pos.Value.X}, {pos.Value.Y}";
+			}
+			else
+			{
+				Tap2Label.Text = $"{pos.Value.X}, {pos.Value.Y}";
+			}
+
+			_taps += 1;
+		}
+	}
+}

src/Controls/src/Core/Platform/Android/InnerGestureListener.cs

@@ -82,22 +82,26 @@ bool GestureDetector.IOnDoubleTapListener.OnDoubleTap(MotionEvent e)
 				return _tapDelegate(2, e);
 			}
 
-			if (HasSingleTapHandler())
+			// If we're getting here and don't have a double-tap handler, we might be looking at multiple
+			// single taps; that'll be handled in OnDoubleTapEvent
+
+			return false;
+		}
+
+		bool GestureDetector.IOnDoubleTapListener.OnDoubleTapEvent(MotionEvent e)
+		{
+			if (!HasDoubleTapHandler() && HasSingleTapHandler() && e.Action == MotionEventActions.Up)
 			{
 				// If we're registering double taps and we don't actually have a double-tap handler,
 				// but we _do_ have a single-tap handler, then we're really just seeing two singles in a row
+
 				// Fire off the delegate for the second single-tap (OnSingleTapUp already did the first one)
 				return _tapDelegate(1, e);
 			}
 
 			return false;
 		}
 
-		bool GestureDetector.IOnDoubleTapListener.OnDoubleTapEvent(MotionEvent e)
-		{
-			return false;
-		}
-
 		bool GestureDetector.IOnGestureListener.OnDown(MotionEvent e)
 		{
 			SetStartingPosition(e);

src/Controls/tests/UITests/Tests/GestureRecognizerUITests.cs

@@ -44,6 +44,20 @@ public void PointerGestureTest()
 			var secondaryLabelText = App.Query("secondaryLabel").First().Text;
 			Assert.IsNotEmpty(secondaryLabelText);
 		}
+
+		[Test]
+		public void DoubleTap()
+		{
+			App.WaitForElement("TargetView");
+			App.EnterText("TargetView", "DoubleTapGallery");
+			App.Tap("GoButton");
+
+			App.WaitForElement("DoubleTapSurface");
+			App.DoubleTap("DoubleTapSurface");
+
+			var result = App.Query("DoubleTapResults").First().Text;
+			Assert.AreEqual("Success", result);
+		}
 	}
 }
 

src/Controls/tests/UITests/Tests/Issues/Issue15357.cs

@@ -1,4 +1,5 @@
-using Microsoft.Maui.Appium;
+using System.Reflection;
+using Microsoft.Maui.Appium;
 using NUnit.Framework;
 
 namespace Microsoft.Maui.AppiumTests.Issues

src/Controls/tests/UITests/Tests/Issues/Issue16561.cs

@@ -0,0 +1,78 @@
+using System.Drawing;
+using Microsoft.Maui.Appium;
+using NUnit.Framework;
+using OpenQA.Selenium.Appium.MultiTouch;
+using TestUtils.Appium.UITests;
+
+namespace Microsoft.Maui.AppiumTests.Issues
+{
+	public class Issue16561 : _IssuesUITest
+	{
+		private string _tapAreaId = "TapArea";
+
+		public Issue16561(TestDevice device) : base(device)
+		{
+		}
+
+		public override string Issue => "Quick single taps on Android have wrong second tap location";
+
+		[Test]
+		public void TapTwoPlacesQuickly()
+		{
+			if (App is not IApp2 app2 || app2 is null || app2.Driver is null)
+			{
+				throw new InvalidOperationException("Cannot run test. Missing driver to run quick tap actions.");
+			}
+
+			var tapAreaResult = App.WaitForElement(_tapAreaId);
+			var tapArea = tapAreaResult[0].Rect;
+
+			// The test harness coordinates are absolute
+			var xOffset = 50;
+			var harnessCenterX = tapArea.CenterX;
+			var harnessCenterY = tapArea.CenterY;
+
+			var point1 = new PointF(harnessCenterX - xOffset, harnessCenterY);
+			var point2 = new PointF(harnessCenterX + xOffset, harnessCenterY);
+
+			// The TapGesture coordinates are relative to the container, so we need to adjust
+			// for the container position
+			var expectedY = harnessCenterY - tapArea.Y;
+			var expectedX1 = point1.X - tapArea.X;
+			var expectedX2 = point2.X - tapArea.X;
+
+			// Just calling Tap twice will be too slow; we need to queue up the actions so they happen quickly
+			var actionsList = new TouchAction(app2.Driver);
+
+			// Tap the first point, then the second point
+			actionsList.Tap(point1.X, point1.Y).Tap(point2.X, point2.Y);
+			app2.Driver.PerformTouchAction(actionsList);
+
+			// The results for each tap should show up in the labels on the screen; find the text
+			// of each tap result and check to see that it meets the expected values
+			var result = App.WaitForElement("Tap1Label");
+			AssertCorrectTapLocation(result[0].Text, expectedX1, expectedY, "First");
+
+			result = App.WaitForElement("Tap2Label");
+			AssertCorrectTapLocation(result[0].Text, expectedX2, expectedY, "Second");
+		}
+
+		static void AssertCorrectTapLocation(string tapData, float expectedX, float expectedY, string which) 
+		{
+			// Turn the text values into numbers so we can compare with a tolerance
+			(var tapX, var tapY) = ParseCoordinates(tapData);
+
+			Assert.AreEqual((double)expectedX, tapX, 1, $"{which} tap has unexpected X value");
+			Assert.AreEqual((double)expectedY, tapY, 1, $"{which} tap has unexpected Y value");
+		}
+
+		static (double, double) ParseCoordinates(string text) 
+		{
+			var values = text.Split(',', StringSplitOptions.TrimEntries)
+				.Select(double.Parse)
+				.ToArray();
+
+			return (values[0], values[1]);
+		}
+	}
+}

src/TestUtils/src/TestUtils.Appium.UITests/AppiumUITestApp.cs

@@ -34,6 +34,13 @@ public class AppiumUITestApp : IApp2
 
 		public static TimeSpan DefaultTimeout = TimeSpan.FromSeconds(15);
 
+		// Using the default value from https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/view/ViewConfiguration.java#129
+		// and shaving off 50ms so we come in under the threshold
+		// iOS and Mac use a different way of simulating double taps, so no need for a variation of this constant for those platforms
+		// The Windows default is 500 ms (https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setdoubleclicktime?redirectedfrom=MSDN#parameters)
+		// so this delay should be short enough to simulate a double-click on that platform.
+		const int DOUBLE_TAP_DELAY_MS = 250;
+
 		readonly Dictionary<string, string> _controlNameToTag = new Dictionary<string, string>
 		{
 			{ "button", "ControlType.Button" }
@@ -115,6 +122,8 @@ public ApplicationState AppState
 			}
 		}
 
+		public AppiumDriver? Driver => _driver;
+
 		public void ResetApp()
 		{
 			_driver?.ResetApp();
@@ -243,11 +252,7 @@ private void DoubleTap(AppiumElement element)
 				PointerInputDevice touchDevice = new PointerInputDevice(PointerType);
 				ActionSequence sequence = new ActionSequence(touchDevice, 0);
 				sequence.AddAction(touchDevice.CreatePointerMove(element, 0, 0, TimeSpan.FromMilliseconds(5)));
-				sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePause(TimeSpan.FromMilliseconds(600)));
-				sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
+				AddDoubleTap(touchDevice, sequence);
 				_driver?.PerformActions(new List<ActionSequence> { sequence });
 			}
 		}
@@ -275,16 +280,22 @@ public void DoubleTapCoordinates(float x, float y)
 			{
 				PointerInputDevice touchDevice = new PointerInputDevice(PointerType);
 				ActionSequence sequence = new ActionSequence(touchDevice, 0);
-				sequence.AddAction(touchDevice.CreatePointerMove(CoordinateOrigin.Viewport, (int)x, (int)y, TimeSpan.FromMilliseconds(5)));
-				sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePause(TimeSpan.FromMilliseconds(600)));
-				sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
-				sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
+				AddDoubleTap(touchDevice, sequence);
 				_driver?.PerformActions(new List<ActionSequence> { sequence });
 			}
 		}
 
+		static ActionSequence AddDoubleTap(PointerInputDevice touchDevice, ActionSequence sequence)
+		{
+			sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
+			sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
+			sequence.AddAction(touchDevice.CreatePause(TimeSpan.FromMilliseconds(DOUBLE_TAP_DELAY_MS)));
+			sequence.AddAction(touchDevice.CreatePointerDown(PointerButton.TouchContact));
+			sequence.AddAction(touchDevice.CreatePointerUp(PointerButton.TouchContact));
+
+			return sequence;
+		}
+
 		public void DragAndDrop(Func<AppQuery, AppQuery> from, Func<AppQuery, AppQuery> to)
 		{
 			DragAndDrop(

src/TestUtils/src/TestUtils.Appium.UITests/IApp2.cs

@@ -1,4 +1,5 @@
-using Xamarin.UITest;
+using OpenQA.Selenium.Appium;
+using Xamarin.UITest;
 
 namespace TestUtils.Appium.UITests
 {
@@ -11,5 +12,6 @@ public interface IApp2 : IApp, IDisposable
 		ApplicationState AppState { get; }
 		bool WaitForTextToBePresentInElement(string automationId, string text);
 		public byte[] Screenshot();
+		public AppiumDriver? Driver { get; }
 	}
 }