[Android] Fix DatePicker MinimumDate/MaximumDate not updating dynamically

[HarishwaranVijayakumar]

Issue Details

• Android DatePicker minimum/maximum date constraints don't update properly when changed dynamically. In a dependent DatePicker scenario (LEFT picker's date sets RIGHT picker's minimum), the RIGHT picker fails to respect the updated minimum date constraint.

Behavior:

• First time setting MinimumDate/MaximumDate → Works correctly
• Second time (or subsequent times) setting MinimumDate/MaximumDate → Fails to update

Root Cause of the issue

• Android's DatePicker internally caches MinDate/MaxDate values and ignores subsequent setMinDate()/setMaxDate() calls unless the values are first reset.

Reference: StackOverflow

Description of Change

Android DatePicker Minimum/Maximum Date Update Fix:

• Framework Fixes:

  • In DatePickerHandler.Android.cs, a handler is added for the dialog's ShowEvent to always re-apply the minimum and maximum dates after the dialog is initialized, ensuring changes are respected even when the dialog is reused.
  • In DatePickerExtensions.cs, both UpdateMinimumDate and UpdateMaximumDate methods now reset the underlying Android values (MinDate to 0, MaxDate to long.MaxValue) before setting the new constraint, forcing Android to invalidate its cached values and accept updates. [1] [2]

• Testing Improvements:

  • Added a new UI test page (Issue19256.cs) to the host app that sets up two dependent DatePicker controls and buttons to simulate the bug scenario and verify the fix.
  • Added a corresponding NUnit UI test that automates the scenario and uses screenshots to verify that the minimum date updates dynamically as expected.

These changes collectively ensure that the Android DatePicker now correctly updates its constraints in response to changes, matching expected behavior.

Issues Fixed

Fixes #19256

Output

Before	After
Before_fix.mov	After_fix.mov

[dotnet-policy-service]

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

[sheiksyedm]

/azp run maui-pr-uitests 

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Copilot]

Pull request overview

This PR fixes a long-standing Android platform bug where DatePicker minimum and maximum date constraints fail to update dynamically after the initial setting. The issue manifests in dependent DatePicker scenarios where changing one picker's date should update another picker's minimum/maximum constraint.

Changes:

• Implements the established Android workaround by resetting min/max values before setting new constraints
• Adds ShowEvent handler to ensure constraints are re-applied after Android's internal dialog initialization
• Includes comprehensive UI tests with screenshot verification to validate the fix

Reviewed changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Core/src/Platform/Android/DatePickerExtensions.cs	Added reset logic (MinDate=0, MaxDate=long.MaxValue) before setting new constraint values to force Android to invalidate cached values
src/Core/src/Handlers/DatePicker/DatePickerHandler.Android.cs	Added ShowEvent handler to re-apply min/max dates after dialog initialization, working around Android's dialog reuse caching issue
src/Controls/tests/TestCases.HostApp/Issues/Issue19256.cs	Created UI test page with two dependent DatePickers and buttons to reproduce the issue scenario
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue19256.cs	Created NUnit test with two-screenshot verification approach to validate dynamic MinimumDate updates
src/Controls/tests/TestCases.Android.Tests/snapshots/android/DatePickerMinimumDateShouldUpdateDynamically_*.png	Reference screenshots for automated visual verification (2 files)
.github/agent-pr-session/pr-19256.md	Agent session documentation tracking the fix development process

[PureWeen]

/rebase

[PureWeen]

/azp run maui-pr-uitests, maui-pr-devicetests

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[PureWeen]

/rebase