生成验证码图片

生成验证码图片

引用 SkiaSharp.dll

private static readonly string RandomString = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWSYZ";

/// <summary>
/// 获取图像数字验证码
/// </summary>
/// <param name="text">验证码内容，如4为数字</param>
/// <returns></returns>
public static byte[] GetVerifyCode(string text)
{
    int width = 128;
    int height = 45;

    Random random = new();

    //创建bitmap位图
    using SKBitmap image = new(width, height, SKColorType.Bgra8888, SKAlphaType.Premul);
    //创建画笔
    using SKCanvas canvas = new(image);
    //填充背景颜色为白色
    canvas.DrawColor(SKColors.Green);

    //画图片的背景噪音线
    //for (int i = 0; i < width * height * 0.015; i++)
    //{
    //    using SKPaint drawStyle = new();
    //    drawStyle.Color = new(Convert.ToUInt32(random.Next(int.MaxValue)));
    //    canvas.DrawLine(random.Next(0, width), random.Next(0, height), random.Next(0, width), random.Next(0, height), drawStyle);
    //}
    //将文字写到画布上
    var fonts = new[] { "Cantarell", "Karla" };
    if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
    {
        fonts = new[] { "宋体" };
    }
    using (SKPaint drawStyle = new())
    {
        var font = SKFontManager.Default.CreateTypeface(File.Open(GetMapPath("/fonts/JetBrainsMono-Bold.ttf"), FileMode.Open));
        drawStyle.Color = SKColors.White;
        drawStyle.TextSize = height;
        drawStyle.StrokeWidth = 2;
        drawStyle.IsAntialias = true;
        drawStyle.Typeface = font;

        float emHeight = height - height * (float)0.14;
        float emWidth = (float)width / text.Length - width * (float)0.13;
        canvas.DrawText(text, emWidth, emHeight, drawStyle);
    }

    //画图片的前景噪音点
    for (int i = 0; i < width * height * 0.6; i++)
    {
        image.SetPixel(random.Next(0, width), random.Next(0, height), new SKColor(Convert.ToUInt32(random.Next(int.MaxValue))));
    }

    using var img = SKImage.FromBitmap(image);
    using SKData p = img.Encode(SKEncodedImageFormat.Png, 100);
    return p.ToArray();
}

 public static string GetRandomString()
 {
     Random random = new();
     StringBuilder sb = new StringBuilder();
     for (int i = 0; i < 4; i++)
     {
         int number = random.Next(RandomString.Length);
         sb.Append(RandomString[number]);
     }
     return sb.ToString();
 }

 public static string GetMapPath(string path)
 {
     if (path.IndexOf("\\") > -1)
     {
         return path;
     }

     if (App.WebHostEnvironment != null)
     {
         if (!string.IsNullOrWhiteSpace(path))
         {
             path = path.Replace("/", "\\");
         }
         return App.WebHostEnvironment.WebRootPath + path;
     }

     string applicationBase = AppDomain.CurrentDomain.SetupInformation.ApplicationBase;
     if (!string.IsNullOrWhiteSpace(path))
     {
         path = path.Replace("/", "\\");
         if (!path.StartsWith("\\"))
         {
             path = "\\" + path;
         }

         path = path.Substring(path.IndexOf('\\') + (applicationBase.EndsWith("\\") ? 1 : 0));
     }

     return applicationBase + path;
 }