asg_backend/asg_form/Controllers/prerfunctions/Draw.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using SkiaSharp;
using System.IO;

public class CaptchaService
{
    public string generatedCaptchaCode;
    public int wrp = 0;
    // 生成验证码图像并返回Base64字符串


public (string captchaImage, string captchaCode) GenerateCaptcha()
{
    string wp = "123";
    try
    {
        string generatedCaptchaCode = GenerateRandomCode(4); // 生成4位随机字符
        int width = 100, height = 40;
            
        using (var bitmap = new SKBitmap(width, height))
        {
                wp = "111";
            using (var canvas = new SKCanvas(bitmap))
            {
                    wp = "333";
                canvas.Clear(SKColors.White);
                using (var paint = new SKPaint())
                {
                    paint.Color = SKColors.Black;
                    paint.TextSize = 20;
                    paint.IsAntialias = true;
                    canvas.DrawText(generatedCaptchaCode, 10, 30, paint);
                }
            }
                wp = "222";
            using (var image = SKImage.FromBitmap(bitmap))
            using (var data = image.Encode(SKEncodedImageFormat.Png, 100))
            using (var ms = new MemoryStream())
            {
                data.SaveTo(ms);
                string base64Image = Convert.ToBase64String(ms.ToArray());
                return (base64Image, generatedCaptchaCode);
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error generating captcha: {ex.Message}");
        return (ex.Message, wp);
    }
}





// 生成随机字符
private string GenerateRandomCode(int length)
    {
        const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ012345689";
        Random random = new Random();
        return new string(Enumerable.Repeat(chars, length)
            .Select(s => s[random.Next(s.Length)]).ToArray());
    }

    

}