如何使用 .NET MAUI 建立桌面條碼應用程式（掃描器/產生器）

接下來，實作使用者點擊按鈕時的邏輯。 在使用者介面中，掃描按鈕附加了一個OnScanButtonClicked事件處理程序。

PickPhotoAsync首先用於讓使用者選擇要上傳的條碼，然後使用OpenReadAsync存取檔案流。 使用CopyToAsync立即將影像資料複製到MemoryStream 。 這樣就可以同時使用資料在螢幕上顯示影像，並讓Read方法掃描條碼。

最後，如果偵測到有效的條碼，則會在使用者介面中顯示條碼值；如果未在影像中找到條碼，則會顯示紅色訊息。

using IronBarCode;

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            // Your license key is set here
            IronBarCode.License.LicenseKey = "YOUR_KEY"
        }

        private async void OnScanButtonClicked(object sender, EventArgs e)
        {
            try
            {
                var fileResult = await MediaPicker.Default.PickPhotoAsync();

                if (fileResult != null)
                {
                    // 1. Copy the file content into a byte array or MemoryStream immediately
                    // This ensures we have the data in memory before the file closes
                    byte[] imageBytes;
                    using (var stream = await fileResult.OpenReadAsync())
                    using (var memoryStream = new MemoryStream())
                    {
                        await stream.CopyToAsync(memoryStream);
                        imageBytes = memoryStream.ToArray();
                    }

                    // 2. Set the Image Source for the UI
                    // We give the UI a FRESH stream from the bytes we just saved
                    ScannerImage.Source = ImageSource.FromStream(() => new MemoryStream(imageBytes));

                    // 3. Process the Barcode
                    // We give IronBarcode its OWN fresh stream from the same bytes
                    using (var processingStream = new MemoryStream(imageBytes))
                    {
                        // 4. Read the barcode with Read
                        var results = BarcodeReader.Read(processingStream);

                        // 5. Display barcode results
                        if (results != null && results.Count > 0)
                        {

                            // Successfully found barcode value
                            ResultLabel.Text = $"Success: {results[0].Value}";
                            ResultLabel.TextColor = Colors.Green;
                        }
                        else
                        {
                            // Image uploaded has no barcode or barcode value is not found
                            ResultLabel.Text = "No barcode detected.";
                            ResultLabel.TextColor = Colors.Red;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                // Display any exception thrown in runtime
                ResultLabel.Text = $"Error: {ex.Message}";
                ResultLabel.TextColor = Colors.Red;
            }
        }
    }
}

using IronBarCode;

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            // Your license key is set here
            IronBarCode.License.LicenseKey = "YOUR_KEY"
        }

        private async void OnScanButtonClicked(object sender, EventArgs e)
        {
            try
            {
                var fileResult = await MediaPicker.Default.PickPhotoAsync();

                if (fileResult != null)
                {
                    // 1. Copy the file content into a byte array or MemoryStream immediately
                    // This ensures we have the data in memory before the file closes
                    byte[] imageBytes;
                    using (var stream = await fileResult.OpenReadAsync())
                    using (var memoryStream = new MemoryStream())
                    {
                        await stream.CopyToAsync(memoryStream);
                        imageBytes = memoryStream.ToArray();
                    }

                    // 2. Set the Image Source for the UI
                    // We give the UI a FRESH stream from the bytes we just saved
                    ScannerImage.Source = ImageSource.FromStream(() => new MemoryStream(imageBytes));

                    // 3. Process the Barcode
                    // We give IronBarcode its OWN fresh stream from the same bytes
                    using (var processingStream = new MemoryStream(imageBytes))
                    {
                        // 4. Read the barcode with Read
                        var results = BarcodeReader.Read(processingStream);

                        // 5. Display barcode results
                        if (results != null && results.Count > 0)
                        {

                            // Successfully found barcode value
                            ResultLabel.Text = $"Success: {results[0].Value}";
                            ResultLabel.TextColor = Colors.Green;
                        }
                        else
                        {
                            // Image uploaded has no barcode or barcode value is not found
                            ResultLabel.Text = "No barcode detected.";
                            ResultLabel.TextColor = Colors.Red;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                // Display any exception thrown in runtime
                ResultLabel.Text = $"Error: {ex.Message}";
                ResultLabel.TextColor = Colors.Red;
            }
        }
    }
}

輸出結果包含找到的條碼值

如您所見，該應用程式顯示了條碼結果和上傳的條碼圖像。

未找到條碼值

如您所見，當使用者上傳不包含條碼的圖片時，會顯示紅色訊息，提示"未找到條碼"。

接下來，實作按鈕點擊事件的邏輯。 UI 中的產生按鈕附加了一個OnGenerateButtonClicked事件處理程序。

使用者輸入經過驗證，以確保文字存在並且已選擇類型，之後將選擇對應到正確的BarcodeEncoding 。 BarcodeWriter.CreateBarcode用於產生影像、調整影像大小並將其轉換為 JPEG 二進位資料。 然後使用MemoryStream將圖像顯示在螢幕上。

最後，使用File.WriteAllBytes將產生的條碼檔案直接儲存到使用者的桌面，並更新狀態標籤以確認儲存位置。

using IronBarCode;
using System.IO; // Required for saving files

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            IronBarCode.License.LicenseKey = "YOUR-KEY";

            // Set default selection
            BarcodeTypePicker.SelectedIndex = 0;
        }

        private void OnGenerateButtonClicked(object sender, EventArgs e)
        {
            try
            {
                // 1. Get and Validate Input
                string text = BarcodeEntry.Text;

                if (string.IsNullOrWhiteSpace(text))
                {
                    StatusLabel.Text = "Error: Please enter text.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                if (BarcodeTypePicker.SelectedIndex == -1)
                {
                    StatusLabel.Text = "Error: Please select a type.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                // 2. Determine Encoding Type
                string selectedType = BarcodeTypePicker.SelectedItem.ToString();
                BarcodeEncoding encoding = BarcodeEncoding.QRCode;

                switch (selectedType)
                {
                    case "QRCode": encoding = BarcodeEncoding.QRCode; break;
                    case "Code128": encoding = BarcodeEncoding.Code128; break;
                    case "EAN13": encoding = BarcodeEncoding.EAN13; break;
                    case "Code39": encoding = BarcodeEncoding.Code39; break;
                    case "PDF417": encoding = BarcodeEncoding.PDF417; break;
                }

                // 3. Generate Barcode
                var barcode = BarcodeWriter.CreateBarcode(text, encoding);
                barcode.ResizeTo(400, 200); // Optional resizing

                // 4. Convert to Bytes (JPEG)
                var bytes = barcode.ToJpegBinaryData();

                // 5. Update UI
                GeneratedImage.Source = ImageSource.FromStream(() => new MemoryStream(bytes));

                // 6. Save to Desktop automatically
                string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
                string fileName = $"barcode_{DateTime.Now:yyyyMMdd_HHmmss}.jpg";
                string fullPath = Path.Combine(desktopPath, fileName);

                File.WriteAllBytes(fullPath, bytes);

                // 7. Show Success Message
                StatusLabel.Text = $"Saved to Desktop:\n{fileName}";
                StatusLabel.TextColor = Colors.Green;
            }
            catch (Exception ex)
            {
                StatusLabel.Text = $"Error: {ex.Message}";
                StatusLabel.TextColor = Colors.Red;
            }
        }
    }
}

using IronBarCode;
using System.IO; // Required for saving files

namespace MauiApp1
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            IronBarCode.License.LicenseKey = "YOUR-KEY";

            // Set default selection
            BarcodeTypePicker.SelectedIndex = 0;
        }

        private void OnGenerateButtonClicked(object sender, EventArgs e)
        {
            try
            {
                // 1. Get and Validate Input
                string text = BarcodeEntry.Text;

                if (string.IsNullOrWhiteSpace(text))
                {
                    StatusLabel.Text = "Error: Please enter text.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                if (BarcodeTypePicker.SelectedIndex == -1)
                {
                    StatusLabel.Text = "Error: Please select a type.";
                    StatusLabel.TextColor = Colors.Red;
                    return;
                }

                // 2. Determine Encoding Type
                string selectedType = BarcodeTypePicker.SelectedItem.ToString();
                BarcodeEncoding encoding = BarcodeEncoding.QRCode;

                switch (selectedType)
                {
                    case "QRCode": encoding = BarcodeEncoding.QRCode; break;
                    case "Code128": encoding = BarcodeEncoding.Code128; break;
                    case "EAN13": encoding = BarcodeEncoding.EAN13; break;
                    case "Code39": encoding = BarcodeEncoding.Code39; break;
                    case "PDF417": encoding = BarcodeEncoding.PDF417; break;
                }

                // 3. Generate Barcode
                var barcode = BarcodeWriter.CreateBarcode(text, encoding);
                barcode.ResizeTo(400, 200); // Optional resizing

                // 4. Convert to Bytes (JPEG)
                var bytes = barcode.ToJpegBinaryData();

                // 5. Update UI
                GeneratedImage.Source = ImageSource.FromStream(() => new MemoryStream(bytes));

                // 6. Save to Desktop automatically
                string desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
                string fileName = $"barcode_{DateTime.Now:yyyyMMdd_HHmmss}.jpg";
                string fullPath = Path.Combine(desktopPath, fileName);

                File.WriteAllBytes(fullPath, bytes);

                // 7. Show Success Message
                StatusLabel.Text = $"Saved to Desktop:\n{fileName}";
                StatusLabel.TextColor = Colors.Green;
            }
            catch (Exception ex)
            {
                StatusLabel.Text = $"Error: {ex.Message}";
                StatusLabel.TextColor = Colors.Red;
            }
        }
    }
}

輸出產生的條碼

如您所見，該應用程式會顯示產生的條碼並將其儲存到使用者的桌面。

輸出失敗

某些條碼類型對輸入值有限制和格式要求。 當條碼產生失敗時，應用程式會顯示 IronBarcode 異常，如上圖所示。 請參考對應的詳細一維和二維條碼格式說明，以了解每種條碼類型的格式要求。

若要測試上述範例（桌面條碼掃描器和桌面條碼產生器），請下載此範例專案。