flutter-plugins/packages/camera/camera_aurora/lib/camera_viewfinder.dart

// SPDX-FileCopyrightText: Copyright 2023 Open Mobile Platform LLC <community@omp.ru>
// SPDX-License-Identifier: BSD-3-Clause
import 'package:camera_aurora/camera_aurora_platform_interface.dart';
import 'package:flutter/material.dart';

import 'camera_data.dart';

class CameraViewfinder extends StatefulWidget {
  const CameraViewfinder({
    super.key,
    required this.width,
    required this.height,
  });

  final double width;
  final double height;

  @override
  State<CameraViewfinder> createState() => _CameraViewfinderState();
}

class _CameraViewfinderState extends State<CameraViewfinder> {
  CameraState _cameraState = CameraState.fromJson({});

  @override
  initState() {
    super.initState();
    CameraAuroraPlatform.instance.startCapture(widget.width, widget.height);
    CameraAuroraPlatform.instance.onChangeState().listen((event) {
      if (mounted) {
        setState(() {
          _cameraState = event;
        });
      }
    });
  }

  @override
  void dispose() {
    super.dispose();
    CameraAuroraPlatform.instance.stopCapture();
  }

  @override
  Widget build(BuildContext context) {
    if (_cameraState.hasError()) {
      return Center(
        child: Text(
          'Error: ${_cameraState.error}',
          style:
              const TextStyle(fontWeight: FontWeight.bold, color: Colors.white),
        ),
      );
    } else if (_cameraState.isNotEmpty()) {
      int turn = 0;

      switch (_cameraState.rotationDisplay) {
        case 0:
          turn = _cameraState.id.contains('front') ? -1 : 1;
          break;
        case 90:
          turn = 0;
          break;
        case 180:
          turn = _cameraState.id.contains('front') ? 1 : -1;
          break;
        default: // 270
          turn = 2;
      }

      double height = 10;
      double width = 10;

      if (_cameraState.height != 0 && _cameraState.width != 0) {
        if (_cameraState.rotationDisplay == 90 ||
            _cameraState.rotationDisplay == 270) {
          width = widget.width * _cameraState.height / _cameraState.width;
          height = widget.height * _cameraState.width / _cameraState.height;
        } else {
          width = _cameraState.height * widget.height / _cameraState.width;
          height = _cameraState.width * widget.width / _cameraState.height;
        }
      }

      return RotatedBox(
        quarterTurns: turn,
        child: SizedBox(
          width: height, // height
          height: width, // widht
          child: Opacity(
            opacity: _cameraState.height == 0 ? 0 : 1,
            child: Texture(textureId: _cameraState.textureId),
          ),
        ),
      );
    }
    return const SizedBox.shrink();
  }
}