Document Android.Window APIs - #554

Pull request overview

This PR replaces remaining To be added. placeholders in the Android.Window XML documentation surface with meaningful summaries/remarks derived from the official Android API reference, improving the generated docs for window/predictive-back/splash screen/surface sync and related APIs.

Changes:

• Updated Android.Window namespace documentation to describe the scope of the API surface.
• Filled in documentation for key Android.Window types/members (parcelable plumbing, splash screen, surface synchronization, predictive-back related APIs).
• Clarified parameter/return/value documentation for several members where placeholders previously existed.

Reviewed changes

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Two Android.Window contracts are inaccurate:

• SplashScreenView documents a non-animatable icon as returning only null, but Android also permits a non-null zero duration.
• SystemOnBackInvokedCallbacks says the callback always removes the task; it always finishes the activity, but removes the task from Recents only when that activity is the task root.

Please document both outcomes in SplashScreenView.xml and the conditional task behavior in SystemOnBackInvokedCallbacks.xml.

Addressed in 4a826d9:

• SplashScreenView.IconAnimationDuration now documents that a non-animatable icon can return null or a non-null zero duration.
• SystemOnBackInvokedCallbacks.FinishAndRemoveTaskCallback now documents that it always finishes its activity and removes the task from Recents only when the activity is the task root.

The two prior fixes are correct, but three independent Android.Window contracts remain:

• Trusted-presentation thresholds must be greater than 0.0 and at most 1.0; zero is invalid.
• SplashScreenView.IconView can return null when no icon view exists.
• SurfaceSyncGroup.Add executes the runnable synchronously on the calling thread and blocks until it completes.

Please document these concrete range, nullability, and execution guarantees.

Addressed in 1f4d7b1:

• TrustedPresentationThresholds now requires minAlpha and minFractionRendered values greater than 0.0 and no greater than 1.0 in both constructor parameters and exposed values.
• SplashScreenView.IconView now documents that it can return null when no icon view exists.
• Both SurfaceSyncGroup.Add overloads now state that their runnable executes synchronously on the calling thread and blocks the method until completion.

The prior range, nullability, and synchronous-execution fixes are correct, but two contracts remain:

• stabilityRequirementMs must be at least 1 millisecond; zero or negative values throw.
• SurfaceSyncGroup.AddTransaction synchronizes only active groups; after completion Android applies the transaction immediately.

Please document the constructor's integer range and the completed-group behavior.

Addressed in 49c3ede:

• TrustedPresentationThresholds.stabilityRequirementMs now documents the minimum 1 ms value and that zero or negative values cause construction to throw IllegalArgumentException.
• SurfaceSyncGroup.AddTransaction now documents that it synchronizes transactions only while the group is active and applies transactions immediately after the group has completed.

The Android.Window stability ranges, nullable results, synchronous execution, and completed-group transaction behavior now match Android.