如何在 Android 上扫描 QR 代码（初学者教程）

// Install via Package Manager Console
Install-Package IronQR

// Or use the .NET CLI
dotnet add package IronQR

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="___PROTECTED_URL_56___"
             xmlns:x="___PROTECTED_URL_57___"
             x:Class="QR_Code_Business_Card.MainPage"
             Title="QR Code Reader">
    <Grid Padding="20" RowDefinitions="Auto,*" ColumnDefinitions="*,Auto,*">

        <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>

        <BoxView Grid.Row="0" Grid.RowSpan="2" Grid.Column="1" 
                 WidthRequest="1" 
                 Color="#E0E0E0" 
                 Margin="10,0" />

        <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();
            // Replace with your actual license key
            // Get a free trial or purchase at: ___PROTECTED_URL_58___
            License.LicenseKey = "License-Key";
        }

        private async void OnScanQRButtonClicked(object sender, EventArgs e)
        {
            try
            {
                // Open file picker to select an image
                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;
                    // Display the selected image
                    SelectedImage.Source = ImageSource.FromFile(filePath);

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

                    // Process QR code in background to keep UI responsive
                    await Task.Run(() =>
                    {
                        // Load the image using IronDrawing
                        var inputBmp = AnyBitmap.FromFile(filePath);
                        // Create QR image input
                        QrImageInput imageInput = new QrImageInput(inputBmp);
                        // Initialize QR reader
                        QrReader reader = new QrReader();
                        // Read QR codes from the image
                        IEnumerable<QrResult> results = reader.Read(imageInput);

                        // Update UI on main thread
                        MainThread.BeginInvokeOnMainThread(() =>
                        {
                            if (results.Any())
                            {
                                // Display the first QR code found
                                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)
            {
                // Handle any errors gracefully
                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))
            {
                // Copy text to clipboard
                await Clipboard.SetTextAsync(ResultEditor.Text);
                // Show success message
                await DisplayAlert("Success", "Text copied to clipboard", "OK");
            }
            else
            {
                // Show error if no text to copy
                await DisplayAlert("Error", "No text to copy", "OK");
            }
        }
    }
}

Imports IronQr
Imports IronSoftware.Drawing
Imports System.Collections.Generic
Imports System.Linq
Imports System.Threading.Tasks
Imports Xamarin.Essentials
Imports Xamarin.Forms

Namespace QR_Code_Business_Card
    Public Partial Class MainPage
        Inherits ContentPage

        Public Sub New()
            InitializeComponent()
            ' Replace with your actual license key
            ' Get a free trial or purchase at: ___PROTECTED_URL_58___
            License.LicenseKey = "License-Key"
        End Sub

        Private Async Sub OnScanQRButtonClicked(sender As Object, e As EventArgs)
            Try
                ' Open file picker to select an image
                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
                    ' Display the selected image
                    SelectedImage.Source = ImageSource.FromFile(filePath)

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

                    ' Process QR code in background to keep UI responsive
                    Await Task.Run(Sub()
                                       ' Load the image using IronDrawing
                                       Dim inputBmp = AnyBitmap.FromFile(filePath)
                                       ' Create QR image input
                                       Dim imageInput As New QrImageInput(inputBmp)
                                       ' Initialize QR reader
                                       Dim reader As New QrReader()
                                       ' Read QR codes from the image
                                       Dim results As IEnumerable(Of QrResult) = reader.Read(imageInput)

                                       ' Update UI on main thread
                                       MainThread.BeginInvokeOnMainThread(Sub()
                                                                               If results.Any() Then
                                                                                   ' Display the first QR code found
                                                                                   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
                ' Handle any errors gracefully
                ResultEditor.Text = $"An error occurred: {ex.Message}"
                LoadingIndicator.IsVisible = False
                LoadingIndicator.IsRunning = False
            End Try
        End Sub

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