public IActionResult GetCaptcha()
{
CaptchaResponseDto dto = new CaptchaResponseDto();
dto = CaptchaHelper.GenerateCaptcha();
return(Ok(dto));
}
public static CaptchaResponseDto GenerateCaptcha()
{
var captchaValue = new CaptchaValue()
{
Value = new RandomNumber().GenerateRandomNumber(4),
LastTimeAttempted = DateTime.Now,
FirstTimeAttempted = DateTime.Now,
NumberOfTimesAttempted = 0
};
int width = 190;
int height = 80;
var fontEmSizes = new int[] { 15, 20, 25, 30, 35 };
var fontNames = new string[]
{
"Trebuchet MS",
"Arial",
"Times New Roman",
"Georgia",
"Verdana",
"Geneva"
};
FontStyle[] fontStyles =
{
FontStyle.Bold,
FontStyle.Italic,
FontStyle.Regular,
FontStyle.Strikeout,
FontStyle.Underline
};
HatchStyle[] hatchStyles =
{
HatchStyle.BackwardDiagonal, HatchStyle.Cross,
HatchStyle.DashedDownwardDiagonal, HatchStyle.DashedHorizontal,
HatchStyle.DashedUpwardDiagonal, HatchStyle.DashedVertical,
HatchStyle.DiagonalBrick, HatchStyle.DiagonalCross,
HatchStyle.Divot, HatchStyle.DottedDiamond, HatchStyle.DottedGrid,
HatchStyle.ForwardDiagonal, HatchStyle.Horizontal,
HatchStyle.HorizontalBrick, HatchStyle.LargeCheckerBoard,
HatchStyle.LargeConfetti, HatchStyle.LargeGrid,
HatchStyle.LightDownwardDiagonal, HatchStyle.LightHorizontal,
HatchStyle.LightUpwardDiagonal, HatchStyle.LightVertical,
HatchStyle.Max, HatchStyle.Min, HatchStyle.NarrowHorizontal,
HatchStyle.NarrowVertical, HatchStyle.OutlinedDiamond,
HatchStyle.Plaid, HatchStyle.Shingle, HatchStyle.SmallCheckerBoard,
HatchStyle.SmallConfetti, HatchStyle.SmallGrid,
HatchStyle.SolidDiamond, HatchStyle.Sphere, HatchStyle.Trellis,
HatchStyle.Vertical, HatchStyle.Wave, HatchStyle.Weave,
HatchStyle.WideDownwardDiagonal, HatchStyle.WideUpwardDiagonal,HatchStyle.ZigZag
};
var bitmap = new Bitmap(width, height, PixelFormat.Format24bppRgb);
var graphics = Graphics.FromImage(bitmap);
graphics.TextRenderingHint = TextRenderingHint.AntiAlias;
var rectangleF = new RectangleF(0, 0, width, height);
var random = new Random();
//Draw background (Lighter colors RGB 100 to 255)
var brush = new HatchBrush(hatchStyles[random.Next
(hatchStyles.Length - 1)], Color.FromArgb((random.Next(100, 255)),
(random.Next(100, 255)), (random.Next(100, 255))), Color.White);
graphics.FillRectangle(brush, rectangleF);
// There is no spoon
var theMatrix = new Matrix();
for (var i = 0; i <= captchaValue.Value.Length - 1; i++)
{
theMatrix.Reset();
var charLength = captchaValue.Value.Length;
var x = width / (charLength + 1) * i;
var y = height / 2;
//Rotate text Random
theMatrix.RotateAt(random.Next(-40, 40), new PointF(x, y));
graphics.Transform = theMatrix;
//Draw the letters with Random Font Type, Size and Color
graphics.DrawString
(
//Text
captchaValue.Value.Substring(i, 1),
//Random Font Name and Style
new Font(fontNames[random.Next(fontNames.Length - 1)],
fontEmSizes[random.Next(fontEmSizes.Length - 1)],
fontStyles[random.Next(fontStyles.Length - 1)]),
//Random Color (Darker colors RGB 0 to 100)
new SolidBrush(Color.FromArgb(random.Next(0, 100),
random.Next(0, 100), random.Next(0, 100))),
x,
random.Next(10, 40)
);
graphics.ResetTransform();
}
var buffer = new byte[16 * 1024];
// Create the base64 string from the bitmap
using (var ms = new MemoryStream())
{
bitmap.Save(ms, ImageFormat.Png);
int read;
while ((read = ms.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
var base64String = Convert.ToBase64String(ms.ToArray());
CaptchaResponseDto dto = new CaptchaResponseDto()
{
CaptchaImage = $"data:image/png;base64,{base64String}",
Key = CryptographyHelper.Crypt(captchaValue.Value)
};
return(dto);
}
}
