ScanQrCodePage.xaml.cs

 
using CommunityToolkit.Maui.Layouts;
// using CommunityToolkit.Mvvm.Input; // Removed page-level commands; commands now reside in ViewModel
using CommunityToolkit.Mvvm.Messaging;
using Microsoft.Maui.Controls.PlatformConfiguration;
using Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;
using NeuroAccessMaui.Services;
using ZXing.Net.Maui;
#if ANDROID
using Android.Graphics;
using AndroidX.Camera.Core;
using AndroidX.Camera.Core.Impl;
using Java.Nio;
using System.Reflection;
using ZXing.Net.Maui.Controls;
using ZXing.Net.Maui.Readers;
#endif
 
namespace NeuroAccessMaui.UI.Pages.Main.QR
{
    public partial class ScanQrCodePage
    {
        public ScanQrCodePage()
        {
            // Create VM (it will PopLatestArgs internally)
            ScanQrCodeViewModel vm = new();
            this.BindingContext = vm; // set before InitializeComponent for compiled bindings
 
            this.InitializeComponent();
 
            // Post-XAML control configuration
            this.LinkEntry.Keyboard = Keyboard.Url;
            this.LinkEntry.IsSpellCheckEnabled = false;
            this.LinkEntry.IsTextPredictionEnabled = false;
 
            StateContainer.SetCurrentState(this.GridWithAnimation, "AutomaticScan");
 
            this.CameraBarcodeReaderView.IsDetecting = false;
            this.CameraBarcodeReaderView.Options = new BarcodeReaderOptions
            {
                Formats = BarcodeFormats.TwoDimensional,
                AutoRotate = true,
                TryHarder = true,
                TryInverted = true,
                Multiple = false,
            };
 
            vm.DoSwitchMode(true);
        }
 
 
        public override async Task OnAppearingAsync()
        {
            // Base Appearing executes ViewModel lifecycle
            await base.OnAppearingAsync();
 
            // Sync initial states from VM
            if (this.BindingContext is ScanQrCodeViewModel vm)
            {
                this.ApplyState(vm.IsAutomaticScan, initial: true);
                this.CameraBarcodeReaderView.IsTorchOn = vm.IsTorchOn;
                this.CameraBarcodeReaderView.CameraLocation = vm.CameraLocation;
                vm.PropertyChanged += this.VmOnPropertyChanged;
            }
        }
 
        public override async Task OnDisappearingAsync()
        {
            if (this.BindingContext is ScanQrCodeViewModel vm)
                vm.PropertyChanged -= this.VmOnPropertyChanged;
            await MainThread.InvokeOnMainThreadAsync(this.CloseCamera);
            await base.OnDisappearingAsync();
        }
 
        private async void VmOnPropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            if (sender is not ScanQrCodeViewModel vm)
                return;
 
            switch (e.PropertyName)
            {
                case nameof(ScanQrCodeViewModel.IsAutomaticScan):
                    await this.Dispatcher.DispatchAsync(() => this.ApplyState(vm.IsAutomaticScan));
                    break;
                case nameof(ScanQrCodeViewModel.IsTorchOn):
                    this.CameraBarcodeReaderView.IsTorchOn = vm.IsTorchOn;
                    break;
                case nameof(ScanQrCodeViewModel.IsDetecting):
                    this.CameraBarcodeReaderView.IsDetecting = vm.IsDetecting;
                    break;
                case nameof(ScanQrCodeViewModel.CameraLocation):
                    this.CameraBarcodeReaderView.CameraLocation = vm.CameraLocation;
                    break;
            }
        }
 
        private async void ApplyState(bool isAutomatic, bool initial = false)
        {
            try
            {
                string current = StateContainer.GetCurrentState(this.GridWithAnimation);
                bool currentlyAutomatic = string.Equals(current, "AutomaticScan", StringComparison.OrdinalIgnoreCase);
                if (currentlyAutomatic == isAutomatic && !initial)
                    return;
 
                if (initial)
                {
                    // Initial setup: avoid animation & camera flip hack to prevent black screen
                    if (isAutomatic)
                    {
                        if (!currentlyAutomatic)
                            StateContainer.SetCurrentState(this.GridWithAnimation, "AutomaticScan");
                        this.LinkEntry.Unfocus();
                        // slight delay to allow native camera initialization before enabling detection
                        await Task.Delay(250);
                        this.CameraBarcodeReaderView.IsDetecting = true;
                    }
                    else
                    {
                        StateContainer.SetCurrentState(this.GridWithAnimation, "ManualScan");
                        this.CameraBarcodeReaderView.IsTorchOn = false;
                        this.CameraBarcodeReaderView.IsDetecting = false;
                        this.LinkEntry.Focus();
                    }
                    return;
                }
 
                if (!isAutomatic)
                {
                    // Enter manual: stop camera
                    this.CameraBarcodeReaderView.IsTorchOn = false;
                    this.CameraBarcodeReaderView.IsDetecting = false;
                    await StateContainer.ChangeStateWithAnimation(this.GridWithAnimation, "ManualScan", CancellationToken.None);
                    this.LinkEntry.Focus();
                }
                else
                {
                    this.LinkEntry.Unfocus();
                    // Re-init camera by flipping (runtime toggle only)
                    if (this.CameraBarcodeReaderView.CameraLocation == CameraLocation.Rear)
                    {
                        this.CameraBarcodeReaderView.CameraLocation = CameraLocation.Front;
                        this.CameraBarcodeReaderView.CameraLocation = CameraLocation.Rear;
                    }
                    else
                    {
                        this.CameraBarcodeReaderView.CameraLocation = CameraLocation.Rear;
                        this.CameraBarcodeReaderView.CameraLocation = CameraLocation.Front;
                    }
                    await StateContainer.ChangeStateWithAnimation(this.GridWithAnimation, "AutomaticScan", CancellationToken.None);
                    this.CameraBarcodeReaderView.IsDetecting = true;
                }
            }
            catch (Exception ex)
            {
                ServiceRef.LogService.LogException(ex);
            }
        }
 
        private
#if ANDROID
            async
#endif
            Task CloseCamera()
        {
            try
            {
                this.CameraBarcodeReaderView.IsDetecting = false;
#if ANDROID
                ICameraInternal? preview = await GetCameraPreview(this.CameraBarcodeReaderView);
                preview?.Close();
#endif
            }
            catch (Exception e)
            {
                ServiceRef.LogService.LogException(e);
            }
#if !ANDROID
            return Task.CompletedTask;
#endif
        }
#if ANDROID
        private static async Task<ICameraInternal?> GetCameraPreview(CameraBarcodeReaderView cameraBarcodeReaderView)
        {
 
            PermissionStatus status = await Permissions.CheckStatusAsync<Permissions.Camera>();
            if (status == PermissionStatus.Denied)
                return null;
 
            BindingFlags BindingFlags = BindingFlags.NonPublic | BindingFlags.Instance;
            PropertyInfo? StrongHandlerProperty = typeof(CameraBarcodeReaderView).GetProperty("StrongHandler", BindingFlags);
            CameraBarcodeReaderViewHandler? CameraBarcodeReaderViewHandler = StrongHandlerProperty?.GetValue(cameraBarcodeReaderView) as CameraBarcodeReaderViewHandler;
            FieldInfo? ManageField = typeof(CameraBarcodeReaderViewHandler).GetField("cameraManager", BindingFlags);
            object? CameraManager = ManageField?.GetValue(CameraBarcodeReaderViewHandler);
            FieldInfo? CameraPreviewField = typeof(CameraBarcodeReaderViewHandler).Assembly.GetType("ZXing.Net.Maui.CameraManager")?.GetField("cameraPreview", BindingFlags);
            Preview? Preview = CameraPreviewField?.GetValue(CameraManager) as Preview;
 
            return Preview?.Camera;
        }
#endif
 
 
        private async void CameraBarcodeReaderView_BarcodesDetected(object sender, BarcodeDetectionEventArgs e)
        {
            string? Result = (e.Results.Length > 0) ? e.Results[0].Value : null;
 
            await this.Dispatcher.DispatchAsync(async () =>
            {
                ScanQrCodeViewModel ViewModel = this.ViewModel<ScanQrCodeViewModel>();
                await ViewModel.SetScannedText(Result);
            });
        }
    }
}