如何在 Android 上扫描 QR 代码（初学者教程）

<?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="QR_Code_Business_Card.MainPage"
             Title="QR Code Reader">
    <Grid Padding="20" RowDefinitions="Auto,*" ColumnDefinitions="*,Auto,*">
        <!-- Left side -->
        <VerticalStackLayout Grid.Row="1" Grid.Column="0" Spacing="20">
            <Button x:Name="ScanQRButton" 
                    Text="Scan QR Code"
                    Clicked="OnScanQRButtonClicked"
                    HorizontalOptions="Fill"
                    BackgroundColor="#6200EE"
                    TextColor="White"
                    FontAttributes="Bold"
                    CornerRadius="10" />
            <Frame BorderColor="#E0E0E0" Padding="0" CornerRadius="10" HasShadow="True">
                <Grid>
                    <Image x:Name="SelectedImage"
                           HeightRequest="300"
                           WidthRequest="300"
                           Aspect="AspectFit" />
                    <ActivityIndicator x:Name="LoadingIndicator"
                                       IsRunning="False"
                                       IsVisible="False"
                                       Color="#6200EE"
                                       VerticalOptions="Center"
                                       HorizontalOptions="Center" />
                </Grid>
            </Frame>
        </VerticalStackLayout>
        <!-- Divider -->
        <BoxView Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" 
                 WidthRequest="1" 
                 Color="#E0E0E0" 
                 Margin="10,0" />
        <!-- Right side -->
        <VerticalStackLayout Grid.Row="1" Grid.Column="2" Spacing="20">
            <Frame BorderColor="#E0E0E0" Padding="10" CornerRadius="10" HasShadow="True">
                <Editor x:Name="ResultEditor"
                        HeightRequest="200"
                        IsReadOnly="True"
                        Placeholder="QR code content will appear here"
                        FontSize="16" />
            </Frame>
            <Button x:Name="CopyTextButton" 
                    Text="Copy Text"
                    Clicked="OnCopyTextButtonClicked"
                    HorizontalOptions="Fill"
                    BackgroundColor="#6200EE"
                    TextColor="White"
                    FontAttributes="Bold"
                    CornerRadius="10" />
        </VerticalStackLayout>
    </Grid>
</ContentPage>

using IronQr;
using IronSoftware.Drawing;
namespace QR_Code_Business_Card
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            License.LicenseKey = "License-Key";
        }

        private async void OnScanQRButtonClicked(object sender, EventArgs e)
        {
            try
            {
                var result = await FilePicker.PickAsync(new PickOptions
                {
                    FileTypes = FilePickerFileType.Images,
                    PickerTitle = "Pick an image with a QR code"
                });

                if (result != null)
                {
                    string filePath = result.FullPath;
                    SelectedImage.Source = ImageSource.FromFile(filePath);

                    // Show loading indicator
                    LoadingIndicator.IsVisible = true;
                    LoadingIndicator.IsRunning = true;
                    ResultEditor.Text = "Processing QR code...";

                    // Process QR code in the background
                    await Task.Run(() =>
                    {
                        var inputBmp = AnyBitmap.FromFile(filePath);
                        QrImageInput imageInput = new QrImageInput(inputBmp);
                        QrReader reader = new QrReader();
                        IEnumerable<QrResult> results = reader.Read(imageInput);

                        MainThread.BeginInvokeOnMainThread(() =>
                        {
                            if (results.Any())
                            {
                                string scannedData = results.First().Value.ToString();
                                ResultEditor.Text = scannedData;
                            }
                            else
                            {
                                ResultEditor.Text = "No QR code found in the image.";
                            }

                            // Hide loading indicator
                            LoadingIndicator.IsVisible = false;
                            LoadingIndicator.IsRunning = false;
                        });
                    });
                }
            }
            catch (Exception ex)
            {
                ResultEditor.Text = $"An error occurred: {ex.Message}";
                LoadingIndicator.IsVisible = false;
                LoadingIndicator.IsRunning = false;
            }
        }

        private async void OnCopyTextButtonClicked(object sender, EventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(ResultEditor.Text))
            {
                await Clipboard.SetTextAsync(ResultEditor.Text);
                await DisplayAlert("Success", "Text copied to clipboard", "OK");
            }
            else
            {
                await DisplayAlert("Error", "No text to copy", "OK");
            }
        }
    }
}

Imports IronQr
Imports IronSoftware.Drawing
Namespace QR_Code_Business_Card
	Partial Public Class MainPage
		Inherits ContentPage

		Public Sub New()
			InitializeComponent()
			License.LicenseKey = "License-Key"
		End Sub

		Private Async Sub OnScanQRButtonClicked(ByVal sender As Object, ByVal e As EventArgs)
			Try
				Dim result = Await FilePicker.PickAsync(New PickOptions With {
					.FileTypes = FilePickerFileType.Images,
					.PickerTitle = "Pick an image with a QR code"
				})

				If result IsNot Nothing Then
					Dim filePath As String = result.FullPath
					SelectedImage.Source = ImageSource.FromFile(filePath)

					' Show loading indicator
					LoadingIndicator.IsVisible = True
					LoadingIndicator.IsRunning = True
					ResultEditor.Text = "Processing QR code..."

					' Process QR code in the background
					Await Task.Run(Sub()
						Dim inputBmp = AnyBitmap.FromFile(filePath)
						Dim imageInput As New QrImageInput(inputBmp)
						Dim reader As New QrReader()
						Dim results As IEnumerable(Of QrResult) = reader.Read(imageInput)

						MainThread.BeginInvokeOnMainThread(Sub()
							If results.Any() Then
								Dim scannedData As String = results.First().Value.ToString()
								ResultEditor.Text = scannedData
							Else
								ResultEditor.Text = "No QR code found in the image."
							End If

							' Hide loading indicator
							LoadingIndicator.IsVisible = False
							LoadingIndicator.IsRunning = False
						End Sub)
					End Sub)
				End If
			Catch ex As Exception
				ResultEditor.Text = $"An error occurred: {ex.Message}"
				LoadingIndicator.IsVisible = False
				LoadingIndicator.IsRunning = False
			End Try
		End Sub

		Private Async Sub OnCopyTextButtonClicked(ByVal sender As Object, ByVal e As EventArgs)
			If Not String.IsNullOrWhiteSpace(ResultEditor.Text) Then
				Await Clipboard.SetTextAsync(ResultEditor.Text)
				Await DisplayAlert("Success", "Text copied to clipboard", "OK")
			Else
				Await DisplayAlert("Error", "No text to copy", "OK")
			End If
		End Sub
	End Class
End Namespace