Camera preview not working in full screen in flutter

Here is an answer that should work

To fix the issue with the camera preview not matching the screen size, you can try the following modifications to the code:

1. Replace the Transform.scale widget with a AspectRatio widget to ensure that the camera preview maintains the correct aspect ratio:

AspectRatio(
  aspectRatio: _cameraController!.value.aspectRatio,
  child: CameraPreview(_cameraController!),
),

2. Update the scale property in the Transform.scale widget to adjust the preview size correctly:

scale: mediaSize.aspectRatio / _cameraController!.value.aspectRatio,

Here’s the modified code:

Widget build(BuildContext context) {
  final mediaSize = MediaQuery.of(context).size;

  return Scaffold(
    extendBody: true,
    extendBodyBehindAppBar: true,
    appBar: AppBar(
      backgroundColor: Colors.transparent,
      elevation: 0,
      leading: Builder(
        builder: (BuildContext context) {
          return IconButton(
            onPressed: () {
              Navigator.pop(context);
            },
            icon: const Icon(
              UniconsLine.multiply,
              color: Colors.white,
              size: 30,
            ),
          );
        },
      ),
    ),
    body: FutureBuilder<void>(
      future: _initializeControllerFuture,
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {
          // If the Future is complete, display the preview.
          return AspectRatio(
            aspectRatio: _cameraController!.value.aspectRatio,
            child: CameraPreview(_cameraController!),
          );
        } else {
          // Otherwise, display a loading indicator.
          return const Center(child: CircularProgressIndicator());
        }
      },
    ),
    floatingActionButton: FloatingActionButton(
      // Provide an onPressed callback.
      onPressed: () async {
        // Take the Picture in a try / catch block. If anything goes wrong,
        // catch the error.
        try {
          // Ensure that the camera is initialized.
          await _initializeControllerFuture;

          // Attempt to take a picture and get the file `image`
          // where it was saved.
          final image = await _cameraController?.takePicture();

          if (!mounted) return;

          // If the picture was taken, display it on a new screen.
          await Navigator.of(context).push(
            MaterialPageRoute(
              builder: (context) => DisplayPictureScreen(
                // Pass the automatically generated path to
                // the DisplayPictureScreen widget.
                imagePath: image!.path,
              ),
            ),
          );
        } catch (e) {
          // If an error occurs, log the error to the console.
          print(e);
        }
      },
      child: (widget.isVideo)
          ? const Icon(UniconsLine.video)
          : const Icon(UniconsLine.camera),
    ),
    floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
  );
}

With these changes, the camera preview should match the screen size correctly.