添加项目文件。

common/Tnb.Common/Captcha/General/GeneralCaptcha.cs

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+using JNPF.Common.Const;
+using JNPF.Common.Manager;
+using JNPF.Common.Extension;
+using JNPF.DependencyInjection;
+using System.Runtime.InteropServices;
+using SkiaSharp;
+
+namespace JNPF.Common.Captcha.General;
+
+/// <summary>
+/// 常规验证码.
+/// </summary>
+public class GeneralCaptcha : IGeneralCaptcha, ITransient
+{
+    private readonly ICacheManager _cacheManager;
+
+    /// <summary>
+    /// 构造函数.
+    /// </summary>
+    /// <param name="cacheManager"></param>
+    public GeneralCaptcha(ICacheManager cacheManager)
+    {
+        _cacheManager = cacheManager;
+    }
+
+    /// <summary>
+    /// 常规验证码.
+    /// </summary>
+    /// <param name="timestamp">时间戳.</param>
+    /// <param name="width">宽度.</param>
+    /// <param name="height">高度.</param>
+    /// <param name="length">长度.</param>
+    /// <returns></returns>
+    public async Task<byte[]> CreateCaptchaImage(string timestamp, int width, int height, int length = 4)
+    {
+        return await Draw(timestamp, width, height, length);
+    }
+
+    /// <summary>
+    /// 画.
+    /// </summary>
+    /// <param name="timestamp">时间抽.</param>
+    /// <param name="width">宽度.</param>
+    /// <param name="height">高度.</param>
+    /// <param name="length">长度.</param>
+    /// <returns></returns>
+    private async Task<byte[]> Draw(string timestamp, int width, int height, int length = 4)
+    {
+        // 颜色列表，用于验证码、噪线、噪点
+        var color = new[] { SKColors.Black, SKColors.Red, SKColors.DarkBlue, SKColors.Green, SKColors.Orange, SKColors.Brown, SKColors.DarkCyan, SKColors.Purple };
+
+        var backcolors = new[] { SKColors.AntiqueWhite, SKColors.WhiteSmoke, SKColors.FloralWhite };
+
+        // 验证码字体集合
+        string[] fonts = new[] { "Cantarell" };
+
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+        {
+            fonts = new[] { "宋体" };
+        }
+
+        // 验证码随机数
+        Random codeRandom = new Random();
+        string code = codeRandom.NextLetterAndNumberString(length); // 随机字符串集合
+
+        // 相当于js的 canvas.getContext('2d')
+        using SKBitmap bmp = new SKBitmap(width, height, SKColorType.Bgra8888, SKAlphaType.Premul);
+
+        // 相当于前端的canvas
+        using SKCanvas canvas = new SKCanvas(bmp);
+
+        // 填充白色背景
+        canvas.DrawColor(backcolors[codeRandom.Next(0, backcolors.Length - 1)]);
+
+        // 样式 跟xaml差不多
+        using SKPaint drawStyle = new SKPaint();
+
+        // 填充验证码到图片
+        for (int i = 0; i < code.Length; i++)
+        {
+            drawStyle.IsAntialias = true;
+            drawStyle.TextSize = 30;
+            var font = SKTypeface.FromFamilyName(fonts[codeRandom.Next(0, fonts.Length - 1)], SKFontStyleWeight.SemiBold, SKFontStyleWidth.ExtraCondensed, SKFontStyleSlant.Upright);
+            drawStyle.Typeface = font;
+            drawStyle.Color = color[codeRandom.Next(0, color.Length - 1)];
+
+            // 写字
+            canvas.DrawText(code[i].ToString(), (i + 1) * 16, 28, drawStyle);
+        }
+
+        // 生成6条干扰线
+        for (int i = 0; i < 6; i++)
+        {
+            drawStyle.Color = color[codeRandom.Next(color.Length)];
+            drawStyle.StrokeWidth = 1;
+            canvas.DrawLine(codeRandom.Next(0, code.Length * 15), codeRandom.Next(0, 60), codeRandom.Next(0, code.Length * 16), codeRandom.Next(0, 30), drawStyle);
+        }
+
+        using var img = SKImage.FromBitmap(bmp);
+        using var p = img.Encode(SKEncodedImageFormat.Png, 100);
+        using var ms = new MemoryStream();
+
+        // 缓存验证码正确集合 
+        await SetCode(timestamp, code, TimeSpan.FromMinutes(5));
+
+        // 保存到流
+        p.SaveTo(ms);
+
+        return ms.ToArray();
+    }
+
+    /// <summary>
+    /// 保存验证码缓存.
+    /// </summary>
+    /// <param name="timestamp">时间戳.</param>
+    /// <param name="code">验证码.</param>
+    /// <param name="timeSpan">过期时间.</param>
+    public async Task<bool> SetCode(string timestamp, string code, TimeSpan timeSpan)
+    {
+        string cacheKey = string.Format("{0}{1}", CommonConst.CACHEKEYCODE, timestamp);
+        return await _cacheManager.SetAsync(cacheKey, code, timeSpan);
+    }
+}