Replace ViewPager2 with Compose-based TaskScreenContainer for Data Collection

[shobhitagarwal1612]

Fixes #3709

This PR overhauls the data collection flow by migrating it to a Compose-based architecture. It removes the legacy ViewPager2 and fragment-based approach (DataCollectionTaskFragment, DataCollectionViewPagerAdapter) in favor of a new TaskScreenContainer. It also refactors event handling to be more deeply integrated with ViewModels.

Key Changes:

• Replace ViewPager2 and task fragments with Compose-based TaskScreenContainer.
• Replace custom TaskMapFragmentContainer with the official Compose AndroidFragment.
• Move map fragment instantiation into individual Compose task screens.
• Simplify event handling in DataCollectionViewModel by removing MutableSharedFlow and using UI effects.
• Remove onButtonClicked parameter from task screens and handle clicks via individual ViewModels.
• Refactor OpenSettings and SetAwaitingPhotoCapture to use DataCollectionViewModel UI effects.
• Fix failing tests and clean up unused imports/parameters.

Steps to verify:

1. Open the app and start a new data collection submission.
2. Verify that you can navigate smoothly between tasks (Next/Previous).
3. Check map-based tasks (Drop Pin, Draw Area, Capture Location) to ensure the map renders correctly and interactions work as expected.
4. Test permission dialogs and photo capture to ensure the new UI effects handle them properly.

@andreia-ferreira PTAL?

[codecov]

Codecov Report

❌ Patch coverage is 66.92308% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.05%. Comparing base (021ec59) to head (0b1f426).

Files with missing lines	Patch %	Lines
...oid/ui/datacollection/tasks/TaskScreenContainer.kt	52.94%	12 Missing and 4 partials ⚠️
...droid/ui/datacollection/DataCollectionViewModel.kt	62.96%	7 Missing and 3 partials ⚠️
.../android/ui/datacollection/DataCollectionScreen.kt	85.00%	0 Missing and 3 partials ⚠️
...ection/tasks/location/CaptureLocationTaskScreen.kt	50.00%	3 Missing ⚠️
...tform/android/ui/datacollection/TaskDataHandler.kt	33.33%	0 Missing and 2 partials ⚠️
...ndroid/ui/datacollection/DataCollectionFragment.kt	75.00%	1 Missing ⚠️
...ui/datacollection/tasks/AbstractTaskMapFragment.kt	0.00%	0 Missing and 1 partial ⚠️
...oid/ui/datacollection/tasks/date/DateTaskScreen.kt	50.00%	0 Missing and 1 partial ⚠️
...lection/tasks/instruction/InstructionTaskScreen.kt	50.00%	0 Missing and 1 partial ⚠️
...ui/datacollection/tasks/number/NumberTaskScreen.kt	50.00%	0 Missing and 1 partial ⚠️
... and 4 more

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3735      +/-   ##
============================================
+ Coverage     68.00%   68.05%   +0.04%     
+ Complexity     1623     1608      -15     
============================================
  Files           370      368       -2     
  Lines          9609     9528      -81     
  Branches       1251     1242       -9     
============================================
- Hits           6535     6484      -51     
+ Misses         2395     2377      -18     
+ Partials        679      667      -12     

Files with missing lines	Coverage Δ
...d/ui/datacollection/tasks/AbstractTaskViewModel.kt	93.33% <100.00%> (+0.11%)	⬆️
...oid/ui/datacollection/tasks/DataCollectionEvent.kt	100.00% <100.00%> (ø)
...ion/tasks/location/CaptureLocationTaskViewModel.kt	93.47% <100.00%> (+0.14%)	⬆️
...n/tasks/multiplechoice/MultipleChoiceTaskScreen.kt	52.27% <100.00%> (ø)
...ui/datacollection/tasks/point/DropPinTaskScreen.kt	66.03% <100.00%> (+3.53%)	⬆️
...datacollection/tasks/polygon/DrawAreaTaskScreen.kt	46.73% <100.00%> (+3.06%)	⬆️
...ndroid/ui/datacollection/DataCollectionFragment.kt	92.59% <75.00%> (-3.41%)	⬇️
...ui/datacollection/tasks/AbstractTaskMapFragment.kt	60.27% <0.00%> (ø)
...oid/ui/datacollection/tasks/date/DateTaskScreen.kt	76.56% <50.00%> (-0.37%)	⬇️
...lection/tasks/instruction/InstructionTaskScreen.kt	87.50% <50.00%> (-0.74%)	⬇️
... and 10 more

... and 2 files with indirect coverage changes

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[andreia-ferreira]

The only issue I found was when restoring a draft where the current task was conditional. Clicking on any of the previous/next buttons makes the app crash. Tested this behavior on master to confirm it's not an existing issue and couldn't reproduce

Screen_recording_20260513_175154.webm

tested on API 24 and 36 and happens on both

[shobhitagarwal1612]

@andreia-ferreira Thanks for catching the bug! I think it was happening because of using relativeIndex instead of absoluteIndex for rendering tasks. But I was unable to reproduce it locally. Could you please try again with your local setup and check if this resolves the issue?

[andreia-ferreira]

thanks for looking into it, I tested it again but it seems to still happen unfortunately. You can try to join this survey link which I used in the recording below, to see if you can reproduce it too

Screen_recording_20260514_105749.webm

[shobhitagarwal1612]

There is an issue with creating new conditional surveys with the web client. Could you please make the above linked survey public or add me as a collaborator?

[andreia-ferreira]

@shobhitagarwal1612 added you to the survey's data collectors. The 'Conditionals test' survey should show up on your device now

[shobhitagarwal1612]

Upon deeper investigation, I found that the issue is happening due to the complete migration from fragment to compose based views. Earlier during draft resume flow, all task fragments were auto-loaded by the view pager. This used to instantiate their view model and add their values to taskDataHandler.

With the new architecture, only the current active task and it's view model are loaded. Therefore, unvisited previous task responses are missing from the collected ValueDelta, causing the crash.

The proposed solution is to pre-populate taskDataHandler with all draft values immediately after data collection state becomes Ready.