Add invisible FragmentHostActivity to support custom HTML in-app messages on NativeActivity

[simonbullen]

This PR adds support for rendering CleverTap’s fragment-based in-app notifications (e.g. custom HTML) in Unreal Engine projects that use a NativeActivity, which does not support fragments.

Problem

CleverTap’s SDK assumes that the current activity is a FragmentActivity, but Unreal-based Android apps typically use NativeActivity. As a result, certain in-app notification types (notably HTML-based ones) fail to display or cause runtime exceptions.

Solution

Introduced a minimal FragmentHostActivity that subclasses AppCompatActivity and provides a safe fragment container.

Added logic to detect when the current activity is not a FragmentActivity, defer the notification, and launch FragmentHostActivity instead.

Once launched, the host activity proceeds with CleverTap’s regular rendering logic.

This approach isolates fragment-specific logic to a dedicated host, without modifying the behavior for apps already using FragmentActivity.

Summary by CodeRabbit

• New Features

  • Introduced a new activity to host in-app notifications that require a fragment environment, ensuring smoother display for specific notification types.
  • Added a custom theme for the new activity, providing a transparent, fullscreen, and title-less appearance for hosted notifications.

• Bug Fixes

  • Improved handling of in-app notifications by deferring their display until a suitable environment is available, preventing display issues.

[coderabbitai[bot]]

Walkthrough

A new activity, FragmentHostActivity, was introduced to host specific in-app notification types requiring a fragment environment without transition animations. The AndroidManifest and styles were updated to support this activity, and logic was added to InAppController to launch the host activity when needed, deferring notification display until the environment is suitable.

Changes

File(s)	Change Summary
clevertap-core/src/main/AndroidManifest.xml	Added FragmentHostActivity declaration with custom theme, no history, singleTop launch mode, and not exported.
clevertap-core/src/main/java/com/clevertap/android/sdk/FragmentHostActivity.java	Introduced FragmentHostActivity class to host fragments without transition animations; includes static launch and hosting state methods, lifecycle overrides, and fragment lifecycle callbacks.
clevertap-core/src/main/java/com/clevertap/android/sdk/inapp/InAppController.java	Updated showInApp to check notification type; launches FragmentHostActivity if needed and re-queues notifications. Added helper method for type checking.
clevertap-core/src/main/res/values/styles.xml	Added CleverTapFragmentHostTheme style for transparent, fullscreen, no-title, and translucent window configuration.

Sequence Diagram(s)

sequenceDiagram
    participant AppActivity as App Activity
    participant InAppController
    participant FragmentHostActivity

    AppActivity->>InAppController: showInApp(notification)
    InAppController->>InAppController: requiresFragmentHost(type)?
    alt Requires Fragment Host & Not in FragmentActivity
        InAppController->>InAppController: Re-queue notification
        InAppController->>FragmentHostActivity: launch(current)
        Note right of FragmentHostActivity: Activity starts with no animation
        FragmentHostActivity->>FragmentHostActivity: onCreate/onResume (set hosting)
        FragmentHostActivity->>FragmentHostActivity: Register fragment lifecycle callbacks
    else
        InAppController->>AppActivity: Display notification
    end

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[simonbullen]

it’s only activated when the current activity doesn’t support fragments. I don’t know why you’d want to fail to display some types of inapp notifications when fragments aren’t supported in the current activity.

When the current activity does support fragments (which is the recommended setup), this patch should have no effect.

That said, the UX of this patch isn’t great, as the underlying NativeActivity can’t be interacted with while the fragment host is active.

I'm hoping the Android team can find a better solution!

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From: CTLalit @.> Sent: Tuesday, May 27, 2025 5:17:02 PM To: CleverTap/clevertap-android-sdk @.> Cc: Simon Bullen @.>; Mention @.> Subject: Re: [CleverTap/clevertap-android-sdk] Add invisible FragmentHostActivity to support custom HTML in-app messages on NativeActivity (PR #809)

@CTLalit requested changes on this pull request.

@simonbullenhttps://github.com/simonbullen I think this is apply changes to all SDK flows. Consider putting behind a flag which can be provided to core-sdk from Unity (any other third party) and make it configurable?

— Reply to this email directly, view it on GitHubhttps://github.com/CleverTap/clevertap-android-sdk/pull/809#pullrequestreview-2869895873, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AWMZFBJ6FS6Q63P67CQNSML3AQGO5AVCNFSM6AAAAAB5XUMKGWVHI2DSMVQWIX3LMV43YUDVNRWFEZLROVSXG5CSMV3GSZLXHMZDQNRZHA4TKOBXGM. You are receiving this because you were mentioned.Message ID: @.***>

[CTLalit]

@simonbullen makes sense, i saw the code of this patch working only when underlying infra does not support fragments (via instanceOf check). We have added this in our docs to use a specific type of activity; but thanks for providing this piece, we will consider getting it checked in after discussion with my team.