MAUI バーコードスキャナー（IronBarcode搭載）: ステップバイステップガイド

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="BarcodeScannerApp.MainPage"
             Title="Barcode Scanner">
    <VerticalStackLayout Padding="20" Spacing="20">
        <Label Text="Point the camera at a barcode"
               FontSize="16"
               HorizontalOptions="Center"
               TextColor="#555555" />
        <Image x:Name="CapturedImage"
               HeightRequest="300"
               Aspect="AspectFit"
               BackgroundColor="#F0F0F0" />
        <Label x:Name="ResultLabel"
               Text="Tap Scan to begin"
               FontSize="18"
               HorizontalOptions="Center"
               FontAttributes="Bold" />
        <Label x:Name="FormatLabel"
               Text=""
               FontSize="13"
               HorizontalOptions="Center"
               TextColor="#888888" />
        <Button Text="Scan Barcode"
                Clicked="OnScanClicked"
                BackgroundColor="#007ACC"
                TextColor="White"
                CornerRadius="8"
                HeightRequest="50" />
        <Button Text="Load from Gallery"
                Clicked="OnPickFromGalleryClicked"
                BackgroundColor="#5C5C5C"
                TextColor="White"
                CornerRadius="8"
                HeightRequest="50" />
    </VerticalStackLayout>
</ContentPage>

using IronBarCode;
using IronSoftware.Drawing;

namespace BarcodeScannerApp;

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private async void OnScanClicked(object sender, EventArgs e)
    {
        await ScanFromSource(() => MediaPicker.Default.CapturePhotoAsync());
    }

    private async void OnPickFromGalleryClicked(object sender, EventArgs e)
    {
        await ScanFromSource(() => MediaPicker.Default.PickPhotoAsync());
    }

    private async Task ScanFromSource(Func<Task<FileResult?>> sourceFunc)
    {
        try
        {
            var photo = await sourceFunc();
            if (photo is null) return;

            using var stream = await photo.OpenReadAsync();
            using var memoryStream = new MemoryStream();
            await stream.CopyToAsync(memoryStream);
            var imageBytes = memoryStream.ToArray();

            // Show the captured image in the UI
            CapturedImage.Source = ImageSource.FromStream(() =>
                new MemoryStream(imageBytes));

            // Process with IronBarcode
            var bitmap = AnyBitmap.FromBytes(imageBytes);
            var options = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Balanced,
                ExpectMultipleBarcodes = false
            };

            var results = await BarcodeReader.ReadAsync(bitmap, options);

            if (results.Any())
            {
                var first = results.First();
                ResultLabel.Text = $"Value: {first.Value}";
                FormatLabel.Text = $"Format: {first.BarcodeType}";
            }
            else
            {
                ResultLabel.Text = "No barcode detected";
                FormatLabel.Text = string.Empty;
            }
        }
        catch (FeatureNotSupportedException)
        {
            await DisplayAlert("Unsupported",
                "Camera is not available on this device.", "OK");
        }
        catch (PermissionException)
        {
            await DisplayAlert("Permission Required",
                "Please grant camera permission in Settings.", "OK");
        }
        catch (Exception ex)
        {
            await DisplayAlert("Error",
                $"Scanning failed: {ex.Message}", "OK");
        }
    }
}

Imports IronBarCode
Imports IronSoftware.Drawing

Namespace BarcodeScannerApp

    Public Partial Class MainPage
        Inherits ContentPage

        Public Sub New()
            InitializeComponent()
        End Sub

        Private Async Sub OnScanClicked(sender As Object, e As EventArgs)
            Await ScanFromSource(Function() MediaPicker.Default.CapturePhotoAsync())
        End Sub

        Private Async Sub OnPickFromGalleryClicked(sender As Object, e As EventArgs)
            Await ScanFromSource(Function() MediaPicker.Default.PickPhotoAsync())
        End Sub

        Private Async Function ScanFromSource(sourceFunc As Func(Of Task(Of FileResult?))) As Task
            Try
                Dim photo = Await sourceFunc()
                If photo Is Nothing Then Return

                Using stream = Await photo.OpenReadAsync()
                    Using memoryStream = New MemoryStream()
                        Await stream.CopyToAsync(memoryStream)
                        Dim imageBytes = memoryStream.ToArray()

                        ' Show the captured image in the UI
                        CapturedImage.Source = ImageSource.FromStream(Function() New MemoryStream(imageBytes))

                        ' Process with IronBarcode
                        Dim bitmap = AnyBitmap.FromBytes(imageBytes)
                        Dim options = New BarcodeReaderOptions With {
                            .Speed = ReadingSpeed.Balanced,
                            .ExpectMultipleBarcodes = False
                        }

                        Dim results = Await BarcodeReader.ReadAsync(bitmap, options)

                        If results.Any() Then
                            Dim first = results.First()
                            ResultLabel.Text = $"Value: {first.Value}"
                            FormatLabel.Text = $"Format: {first.BarcodeType}"
                        Else
                            ResultLabel.Text = "No barcode detected"
                            FormatLabel.Text = String.Empty
                        End If
                    End Using
                End Using
            Catch ex As FeatureNotSupportedException
                Await DisplayAlert("Unsupported", "Camera is not available on this device.", "OK")
            Catch ex As PermissionException
                Await DisplayAlert("Permission Required", "Please grant camera permission in Settings.", "OK")
            Catch ex As Exception
                Await DisplayAlert("Error", $"Scanning failed: {ex.Message}", "OK")
            End Try
        End Function
    End Class

End Namespace