[Android] "The specified child already has a parent" crash — multiple root causes in ScreenshotPreventImpl.java

[JVGS1111]

This text was written by an AI, but reviewed by a human. The problem is real, please read it.

Summary

We've been experiencing crashes affecting a significant portion of our Android users in production after integrating react-native-screenshot-prevent. The error is:

IllegalStateException: The specified child already has a parent.
You must call removeView() on the child's parent first.

I haven't opened a PR yet because I'm still validating the fix in production, but I wanted to report the issues as soon as possible given the user impact.

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Root Causes Found

1. disableSecureView used hardcoded root view instead of actual parent

// ORIGINAL — crashes if overlayLayout was reparented (e.g. after onHostPause)
ViewGroup rootView = (ViewGroup) activity.getWindow().getDecorView().getRootView();
rootView.removeView(overlayLayout); // IllegalStateException if parent != rootView

onHostPause adds overlayLayout to rootView, but the overlay may have a different actual parent by the time disableSecureView runs. The fix is to always remove from overlayLayout.getParent().

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2. enableSecureView decoded the bitmap on the UI thread

decodeImageUrl() (which opens a network connection) was called synchronously before dispatching to runOnUiThread. This blocks the UI thread and can also cause the overlay to be created in an inconsistent state.

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3. onHostPause / onHostResume cycle causes double-attach crash

onHostPause adds the overlay to rootView. If enableSecureView is called again before onHostResume cleans up, createOverlay is skipped (overlayLayout != null), but the next onHostPause tries to rootView.addView(overlayLayout) when it already has a parent — crash.

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4. onHostDestroy is wired up in ScreenshotPreventImpl but never called from the old arch module

// android/src/oldArch/java/.../RNScreenshotPreventModule.java
@Override
public void onHostDestroy() {
    // Cleanup if needed  ← ScreenshotPreventImpl.onHostDestroy() is never called!
}

The new onHostDestroy() method added in ScreenshotPreventImpl is dead code for old architecture users.

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5. New arch module has no lifecycle listener at all

android/src/newArch/java/.../RNScreenshotPreventModule.java does not implement LifecycleEventListener, meaning onHostPause and onHostResume logic in ScreenshotPreventImpl is completely bypassed for New Architecture apps.

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6. Timing race between background bitmap decode and disableSecureView

Even after moving bitmap decode to a background thread, there's a window:

1. enableSecureView called → background thread starts (network decode can take 200–500ms)
2. Component unmounts → disableSecureView called → overlayLayout == null, noop
3. Background thread finishes → overlay is permanently created and never removed

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Proposed Fixes (being validated in production)

• Always use ((ViewGroup) overlayLayout.getParent()).removeView(overlayLayout) instead of assuming rootView is the parent
• Guard every removal with overlayLayout.getParent() != null before casting and removing
• Decode the bitmap in a background thread before dispatching to UI thread
• Wire onHostDestroy in old arch module to ScreenshotPreventImpl.onHostDestroy()
• Add LifecycleEventListener to the new arch module
• Add a cancellation flag to the background thread in enableSecureView to prevent late overlay creation after disableSecureView was already called

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Environment

• react-native-screenshot-prevent: 1.2.2
• React Native: 0.77+
• Architecture: Old Arch (confirmed), New Arch (likely affected too)
• Platform: Android only