[Android] GraphicsView: prevent TapGesture crash when previous touch points are empty

[michalpobuta]

Summary

Fixes an Android crash path in PlatformTouchGraphicsView.TouchesMoved when previous touch points can be empty.

• Updated src/Core/src/Platform/Android/PlatformTouchGraphicsView.cs
  • Changed guard from points.Length == 1 to _lastMovedViewPoints.Length > 0 before reading _lastMovedViewPoints[0].

Tests

Added/updated Issue34296 UI test coverage:

• src/Controls/tests/TestCases.HostApp/Issues/Issue34296.cs
• src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue34296.cs

Test verifies tapping the GraphicsView twice updates the status label to TapCount:2 and does not crash.

Local Validation

./.dotnet/dotnet tool run pwsh .github/scripts/BuildAndRunHostApp.ps1 -Platform android -TestFilter "Issue34296"

Result: ✅ All tests passed (SUCCESS) on Android

Issues fixed

Fixes #34296

Platforms Affected

• ✅ Android

[github-actions]

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curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 34348

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[dotnet-policy-service]

Hey there @@michalpobuta! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[Copilot]

Pull request overview

Fixes an Android crash in PlatformTouchGraphicsView.TouchesMoved that can occur when prior touch points are empty, and adds an Issue34296 UI test to validate tapping a GraphicsView does not crash.

Changes:

• Android: Adjusted the TouchesMoved drag-start guard to avoid indexing into an empty “previous points” array.
• Tests (HostApp): Added an Issue34296 page with a GraphicsView + TapGestureRecognizer to exercise the crash path.
• Tests (Shared): Added an Issue34296 NUnit/Appium test that taps the GraphicsView twice and verifies TapCount:2.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Core/src/Platform/Android/PlatformTouchGraphicsView.cs	Updates the move/drag guard logic intended to prevent the crash when previous touch points are empty.
src/Controls/tests/TestCases.HostApp/Issues/Issue34296.cs	Adds a repro page with a tappable GraphicsView and status label used by the UI test.
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue34296.cs	Adds an Appium-based UITest that taps the GraphicsView twice and asserts the tap count text.

Comments suppressed due to low confidence (1)

src/Core/src/Platform/Android/PlatformTouchGraphicsView.cs:96

• The new guard prevents _lastMovedViewPoints[0] from throwing when the previous points were empty, but this block still reads points[0] unconditionally and also changes the original single-touch behavior (points.Length == 1). Consider guarding on both arrays (e.g., require points.Length > 0 and preserve the original single-touch check) so multi-touch moves aren’t accidentally treated as a small-delta tap and empty points can’t crash this method (it’s public and can be called directly).

				if (_lastMovedViewPoints.Length > 0)
				{
					float deltaX = _lastMovedViewPoints[0].X - points[0].X;
					float deltaY = _lastMovedViewPoints[0].Y - points[0].Y;

---

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[Copilot]

To reduce UI test flakiness, consider waiting for the label to reach the expected value after the second tap (e.g., WaitForTextToBePresentInElement on Issue34296StatusLabel with TapCount:2) before calling GetText() and asserting. Reading immediately after App.Tap can race the UI update on slower devices.

Suggested change

	App.WaitForTextToBePresentInElement("Issue34296StatusLabel", "TapCount:2");

[Copilot]

This page is intended to exercise the specific Android crash path by calling TouchesBegan(Array.Empty<PointF>()) followed by TouchesMoved(...). Right now, if graphicsView.Handler/PlatformView isn’t the expected PlatformTouchGraphicsView for any reason, the test will still pass and won’t actually validate the fix. Consider making this explicit (e.g., update the status label to an error state or throw in DEBUG when the platform view isn’t found) so the UITest can fail if the reproduction path wasn’t executed.

Suggested change

	}
	#endif
	}
	else
	{
	#if DEBUG
	throw new InvalidOperationException("Issue34296: Expected PlatformTouchGraphicsView as PlatformView but it was not found.");
	#else
	_statusLabel.Text = "Error: PlatformTouchGraphicsView not found";
	return;
	#endif
	}
	#endif

[kubaflo]

Duplicate of #34301