ZhiYi/ZhiYi.Core.Application/Captcha/CaptchaService.cs


using SixLabors.ImageSharp.Drawing.Processing;

namespace ZhiYi.Core.Application.Captcha
{
    public class CaptchaService
    {
        private readonly IDatabase _redis;

        public CaptchaService(IConnectionMultiplexer redis)
        {
            _redis = redis.GetDatabase();
        }

        // 生成验证码图片 linux不支持
        /*public byte[] GenerateCaptchaImage(string captchaText)
        {
            using var bitmap = new Bitmap(120, 40);
            using var graphics = Graphics.FromImage(bitmap);
            graphics.Clear(Color.White);

            // 绘制验证码文本
            var font = new Font("Arial", 20, FontStyle.Bold);
            var brush = new SolidBrush(Color.Black);
            graphics.DrawString(captchaText, font, brush, 10, 10);

            // 添加干扰线
            var random = new Random();
            for (int i = 0; i < 10; i++)
            {
                var pen = new Pen(Color.FromArgb(random.Next(256), random.Next(256), random.Next(256)), 1);
                graphics.DrawLine(pen, random.Next(120), random.Next(40), random.Next(120), random.Next(40));
            }

            // 将图片转换为字节数组
            using var stream = new MemoryStream();
            bitmap.Save(stream, ImageFormat.Png);
            return stream.ToArray();
        }*/

        // 生成随机验证码文本
        public string GenerateCaptchaText(int length = 4)
        {
            const string chars = "ZhiYiCode";
            var random = new Random();
            var captchaText = new StringBuilder();
            for (int i = 0; i < length; i++)
            {
                captchaText.Append(chars[random.Next(chars.Length)]);
            }
            return captchaText.ToString();
        }

        public byte[] GenerateCaptchaImageByImageSharp(string captchaText)
        {
            // 创建一个 120x40 的空白图片
            using var image = new Image<Rgba32>(120, 40);

            // 设置背景颜色为白色
            image.Mutate(ctx => ctx.Fill(SixLabors.ImageSharp.Color.White));

            // 加载字体

            // 创建字体和文本选项
            var fontCollection = new FontCollection();
            //var fontFamily = fontCollection.Add("Arial"); // 使用Arial字体，或者指定其他字体
            var fontFamily = SystemFonts.Get("Arial"); // 使用系统字体
            var font = fontFamily.CreateFont(20); // 创建Font对象，指定字体大小

            // 绘制验证码文本
            var textOptions = new RichTextOptions(font)
            {
                Origin = new PointF(10, 10), // 文本起始位置
                HorizontalAlignment = HorizontalAlignment.Left,
                VerticalAlignment = VerticalAlignment.Top
            };

            image.Mutate(ctx => ctx.DrawText(textOptions, captchaText, Color.Black));

            // 添加干扰线
            var random = new Random();
            for (int i = 0; i < 10; i++)
            {
                var color = Color.FromRgb((byte)random.Next(256), (byte)random.Next(256), (byte)random.Next(256));
                var pen = new SolidPen(color, 1); // 使用 SolidPen 替代 Pen
                var start = new PointF(random.Next(120), random.Next(40));
                var end = new PointF(random.Next(120), random.Next(40));
                image.Mutate(ctx => ctx.DrawLine(pen, start, end));
            }

            // 将图片转换为字节数组
            using var stream = new MemoryStream();
            image.Save(stream, new SixLabors.ImageSharp.Formats.Png.PngEncoder());
            return stream.ToArray();
        }


        /*/// <summary>
        /// 绘制验证码图片，返回图片的字节数组
        /// </summary>
        /// <param name="code"></param>
        /// <param name="length">验证码长度</param>
        /// <returns></returns>
        public byte[] DrawVerifyCode(out string code, int length = 6)
        {
            code = _stringHelper.GenerateRandom(length);
            using var img = new Image<Rgba32>(4 + 16 * code.Length, 40);
            var font = new Font(SystemFonts.Families.First(), 16, FontStyle.Regular);
            var codeStr = code;
            img.Mutate(x =>
            {
                x.BackgroundColor(Color.WhiteSmoke);

                var r = new Random();

                //画噪线 
                for (var i = 0; i < 4; i++)
                {
                    int x1 = r.Next(img.Width);
                    int y1 = r.Next(img.Height);
                    int x2 = r.Next(img.Width);
                    int y2 = r.Next(img.Height);
                    x.DrawLine(new Pen(_colors.RandomGet(), 1L), new PointF(x1, y1), new PointF(x2, y2));
                }

                //画验证码字符串 
                for (int i = 0; i < codeStr.Length; i++)
                {
                    x.DrawText(codeStr[i].ToString(), font, _colors.RandomGet(), new PointF((float)i * 16 + 4, 8));
                }
            });

            using var stream = new MemoryStream();
            img.SaveAsPng(stream);
            return stream.GetBuffer();
        }

        /// <summary>
        /// 绘制验证码图片，返回图片的Base64字符串
        /// </summary>
        /// <param name="code"></param>
        /// <param name="length">验证码长度</param>
        /// <returns></returns>
        public string DrawVerifyCodeBase64String(out string code, int length = 6)
        {
            var bytes = DrawVerifyCode(out code, length);

            return "data:image/png;base64," + Convert.ToBase64String(bytes);
        }*/

        // 存储验证码
        public void StoreCaptcha(string captchaId, string captchaText)
        {
            _redis.StringSet(captchaId, captchaText, TimeSpan.FromMinutes(5)); // 5 分钟有效期
        }

        // 验证用户输入的验证码
        public bool ValidateCaptcha(string captchaId, string userInput)
        {
            var value = _redis.StringGet($"captcha:{captchaId}");
            if (value.HasValue)
            {
                return value == userInput;
            }
            return false;
        }
    }
}