dotnet add package FreeSpire.Barcode

@page
@model IndexModel
@{
    ViewData["Title"] = "QR Code Generator";
}

<h2 style="font-family: Arial; color: #2c3e50;">QR Code Generator</h2>

<form method="post" style="margin-bottom:20px; background-color:#f9f9f9; padding:15px; border-radius:5px; width: fit-content;">
    <label for="InputData" style="font-weight:bold;">Enter text or URL:</label><br />
    <input type="text" id="InputData" name="InputData" style="width:300px; padding:5px; margin:5px 0;" required />
    <button type="submit" style="padding:5px 15px; background-color:#3498db; color:white; border:none; border-radius:3px; cursor:pointer;">
        Generate QR Code
    </button>
</form>

@if (!string.IsNullOrEmpty(Model.QrCodeBase64))
{
    <div style="margin-top:20px; border:1px solid #ddd; padding:10px; display:inline-block; border-radius:5px;">
        <img src="data:image/png;base64,@Model.QrCodeBase64" alt="QR Code" style="display:block; margin-bottom:10px;" />
        <a href="data:image/png;base64,@Model.QrCodeBase64" rel="external nofollow"  download="qrcode.png" 
           style="background-color:#2ecc71; color:white; padding:5px 10px; border-radius:3px; text-decoration:none;">
            Download QR Code
        </a>
    </div>
}

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Spire.Barcode;

public class IndexModel : PageModel
{
    [BindProperty]
    public string InputData { get; set; }

    public string QrCodeBase64 { get; set; }

    public void OnPost()
    {
        if (!string.IsNullOrWhiteSpace(InputData))
        {
            QrCodeBase64 = GenerateQrCodeBase64(InputData);
        }
    }
    
    private string GenerateQrCodeBase64(string input)
    {
        var settings = new BarcodeSettings
        {
            Type = BarCodeType.QRCode,            // 指定二維碼類型
            Data = input,                         // 編碼數(shù)據(jù)
            Data2D = input,                       // 二維碼需要設(shè)置 Data2D
            QRCodeDataMode = QRCodeDataMode.Byte, // 字節(jié)模式（支持多語(yǔ)言）
            QRCodeECL = QRCodeECL.M,              // 中等級(jí)糾錯(cuò)（可恢復(fù) 15% 數(shù)據(jù)）
            X = 3,                                // 模塊大小
            ShowText = false,                     // 不顯示默認(rèn)條碼文字
            ShowBottomText = true,                // 顯示自定義底部文字
            BottomText = input                    // 底部顯示輸入內(nèi)容
        };

        var generator = new BarCodeGenerator(settings);
        using var ms = new MemoryStream();
        var qrImage = generator.GenerateImage();
        qrImage.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        return Convert.ToBase64String(ms.ToArray());
    }
}