Flutter UI with elements positioned incorrectly on Samsung Devices

Flutter UI with elements positioned incorrectly on Samsung Devices

Posted on by Toma Velev

What could be the reason Flutter UI with UI elements positioned correctly on your devices, but are not placed correctly on Samsung Devices?

Possible Reasons for Positioning Differences in Flutter UI

Flutter is designed to provide pixel-perfect rendering across devices by using logical pixels (via MediaQuery), which abstracts away physical differences in screen density, size, and aspect ratio. Based on common Flutter behaviors and device-specific quirks, here are the most likely culprits for the positioning mismatch on the S21 Ultra, along with explanations and fixes. I’ll prioritize the top suspects.

1. Incorrect Handling of Safe Areas (Notches, Status Bar, Navigation Bar)

  • Why this happens: The S21 Ultra has a punch-hole camera (notch) at the top and a potentially taller navigation bar at the bottom compared to the slimmer bezels on the Pixel 8a and iPhone 12. Flutter’s SafeArea widget (or raw MediaQuery.padding) relies on the OS to report these insets accurately. Samsung’s One UI can sometimes report slightly different padding values (e.g., due to gesture navigation or status bar height variations), leading to UI elements shifting up/down by 10-20 pixels. This is more noticeable on larger screens where absolute positioning (e.g., fixed top: 50.0) doesn’t scale.
  • Evidence: Flutter docs emphasize SafeArea for avoiding OS intrusions like notches, and community reports (e.g., on Reddit and Stack Overflow) highlight Android-specific padding inconsistencies on Samsung flagships.
  • How to diagnose/fix:
    • Wrap your root widget (e.g., Scaffold body) in SafeArea(child: YourUI()).
    • Print MediaQuery.of(context).padding in your build method and compare logs across devices—look for differences in top or bottom.
    • If using custom positioning, add maintainBottomViewPadding: true to SafeArea for navigation bar quirks.
    • Test: Run on S21 Ultra with/without gesture navigation enabled (Settings > Display > Navigation bar).

2. Non-Responsive Layout (Hardcoded Sizes or Positions)

  • Why this happens: If your UI uses absolute values like Positioned(top: 100.0, left: 50.0) in a Stack, or fixed widths/heights in Containers without MediaQuery scaling, it won’t adapt to the S21 Ultra’s taller/wider canvas (~20% more height than Pixel 8a). Logical pixels help, but without relative sizing, elements “float” differently on bigger screens. iPhone and Pixel’s similar sizes mask this, but the Ultra exposes it.
  • Evidence: Flutter best practices (e.g., from Medium articles and official cookbook) stress using MediaQuery.sizeOf(context) for responsive designs. Reddit threads on r/FlutterDev report overflows/shifts on S23 Ultra (similar to S21) due to unscaled layouts.
  • How to diagnose/fix:
    • Replace fixed values with relatives: e.g., top: MediaQuery.of(context).size.height * 0.1.
    • Use LayoutBuilder or OrientationBuilder for dynamic constraints: 
      LayoutBuilder(
  builder: (context, constraints) {
    if (constraints.maxWidth > 400) { // S21 Ultra threshold
      return Positioned(top: constraints.maxHeight * 0.05, ...);
    }
    return Positioned(top: 50.0, ...); // Fallback for smaller screens
  },
)
    • For grids/lists, wrap in SingleChildScrollView to handle overflow.

3. Device Pixel Ratio (DPR) Mismatch in Sizing

  • Why this happens: The S21 Ultra’s DPR is ~3.24 (higher than Pixel 8a’s ~2.6 or iPhone 12’s ~3.0), affecting how Flutter converts logical to physical pixels. If you’re manually scaling (e.g., via MediaQuery.devicePixelRatio), small miscalculations can shift positions by a few pixels, especially in high-DPI renders. Emulators often default to lower DPR, exacerbating test discrepancies.
  • Evidence: Stack Overflow discussions note DPR differences causing size mismatches on S21-series devices vs. emulators/Pixels.
  • How to diagnose/fix:
    • Log MediaQuery.of(context).devicePixelRatio on each device—avoid manual scaling; let Flutter handle it.
    • Use packages like flutter_screenutil for DPR-agnostic sizing: ScreenUtil().setWidth(100) scales based on a reference device.
    • Avoid: Custom DPR multipliers; stick to logical pixels.

4. Orientation or Viewport Reporting Differences

  • Why this happens: Even in portrait, Samsung’s One UI can report slightly altered MediaQuery values (e.g., viewInsets for keyboard or orientation flips) due to custom animations or edge-to-edge display modes. If your layout depends on MediaQuery.orientationOf(context), a minor discrepancy could reposition elements.
  • Evidence: Flutter docs warn against over-relying on MediaQuery.orientationOf for UI decisions; it’s better for quick checks but can lag on Android rotations.
  • How to diagnose/fix:
    • Use OrientationBuilder instead for rebuilds on rotation: 
      OrientationBuilder(
  builder: (context, orientation) {
    return orientation == Orientation.portrait 
      ? PortraitLayout() 
      : LandscapeLayout();
  },
)
    • Force consistent reporting: Set SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp]) in main.dart if rotation isn’t needed.

5. Platform-Specific Rendering or Theme Overrides (Less Likely)

  • Why this happens: Material widgets (Android) vs. Cupertino (iOS) can subtly differ in padding/margins. On Samsung, One UI themes might inject extra system-level styling, but Flutter isolates this well—still, if using Theme.of(context) without checks, it could vary.
  • Evidence: Google Groups and Quora threads discuss platform-aware UIs, with Android (Samsung) showing minor scrollbar/status bar diffs vs. iOS/Pixel.
  • How to diagnose/fix: Use if (Platform.isAndroid) for Samsung tweaks, or test with ThemeData(useMaterial3: true) for consistency.

Quick Testing Workflow

  • Emulate the S21 Ultra: In Android Studio, create an AVD with 1440×3200 resolution, 3.24x density, and API 34+ to replicate.
  • Debug Tool: Add Flutter Inspector overlays or debugPaintSizeEnabled = true in main.dart to visualize bounds.
  • Cross-Device Logs: Use flutter run --release on physical devices and compare flutter logs for MediaQuery outputs.
  • Packages for Help: responsive_builder or screen_fit for auto-scaling.

If none of these fit, share your widget tree code (e.g., the Stack or Positioned usage) for more targeted advice. In most cases, wrapping in SafeArea and using relative MediaQuery sizing resolves 80% of these issues—Flutter’s strength is consistency once adapted!