public static CaptchaMessage GetCaptcha()
{
string captchaText = generateRandomString(5).ToUpper();
CaptchaMessage captchaMsg = GenerateImage(captchaText, 100, 20, "Arial");
return(captchaMsg);
}
private static CaptchaMessage GenerateImage(string text, int width, int height, string fontFamily)
{
Random random = new Random();
// Create a new 32-bit bitmap image.
Bitmap bitmap = new Bitmap(width, height, PixelFormat.Format32bppArgb);
// Create a graphics object for drawing.
Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = SmoothingMode.AntiAlias;
Rectangle rect = new Rectangle(0, 0, width, height);
// Fill in the background.
HatchBrush hatchBrush = new HatchBrush(HatchStyle.Wave, Color.LightGray, Color.White);
g.FillRectangle(hatchBrush, rect);
// Set up the text font.
SizeF size;
float fontSize = rect.Height + 1;
Font font;
StringFormat format = new StringFormat();
format.Alignment = StringAlignment.Center;
format.LineAlignment = StringAlignment.Center;
// Adjust the font size until the text fits within the image.
do
{
fontSize--;
font = new Font(fontFamily, fontSize, FontStyle.Bold);
size = g.MeasureString(text, font, new SizeF(width, height), format);
} while (size.Width > rect.Width);
// Create a path using the text and warp it randomly.
GraphicsPath path = new GraphicsPath();
path.AddString(text, font.FontFamily, (int)font.Style, font.Size, rect, format);
float v = 4F;
PointF[] points =
{
new PointF(random.Next(rect.Width) / v, random.Next(rect.Height) / v),
new PointF(rect.Width - random.Next(rect.Width) / v, random.Next(rect.Height) / v),
new PointF(random.Next(rect.Width) / v, rect.Height - random.Next(rect.Height) / v),
new PointF(rect.Width - random.Next(rect.Width) / v, rect.Height - random.Next(rect.Height) / v)
};
Matrix matrix = new Matrix();
matrix.Translate(0F, 0F);
path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
// Draw the text.
hatchBrush = new HatchBrush(HatchStyle.DashedUpwardDiagonal, Color.DarkGray, Color.Black);
g.FillPath(hatchBrush, path);
// Add some random noise.
int m = Math.Max(rect.Width, rect.Height);
for (int i = 0; i < (int)(rect.Width * rect.Height / 30F); i++)
{
int x = random.Next(rect.Width);
int y = random.Next(rect.Height);
int w = random.Next(m / 50);
int h = random.Next(m / 50);
g.FillEllipse(hatchBrush, x, y, w, h);
}
// Clean up.
font.Dispose();
hatchBrush.Dispose();
g.Dispose();
CaptchaMessage message = new CaptchaMessage();
message.RequiredAnswer = text;
message.CaptchaImage = bitmap;
message.CaptchaHash = encryptStr(encryptStr(text, captcahSalt, true) + "$##$" + DateTime.Now.ToString(), captcahSalt, true).Replace("=", "~A");
return(message);
}
private static CaptchaMessage GenerateImage(string text, int width, int height, string fontFamily)
{
Random random = new Random();
// Create a new 32-bit bitmap image.
Bitmap bitmap = new Bitmap(width, height, PixelFormat.Format32bppArgb);
// Create a graphics object for drawing.
Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = SmoothingMode.AntiAlias;
Rectangle rect = new Rectangle(0, 0, width, height);
// Fill in the background.
HatchBrush hatchBrush = new HatchBrush(HatchStyle.Wave, Color.LightGray, Color.White);
g.FillRectangle(hatchBrush, rect);
// Set up the text font.
SizeF size;
float fontSize = rect.Height + 1;
Font font;
StringFormat format = new StringFormat();
format.Alignment = StringAlignment.Center;
format.LineAlignment = StringAlignment.Center;
// Adjust the font size until the text fits within the image.
do
{
fontSize--;
font = new Font(fontFamily, fontSize, FontStyle.Bold);
size = g.MeasureString(text, font, new SizeF(width, height), format);
} while (size.Width > rect.Width);
// Create a path using the text and warp it randomly.
GraphicsPath path = new GraphicsPath();
path.AddString(text, font.FontFamily, (int)font.Style, font.Size, rect, format);
float v = 4F;
PointF[] points =
{
new PointF(random.Next(rect.Width) / v, random.Next(rect.Height) / v),
new PointF(rect.Width - random.Next(rect.Width) / v, random.Next(rect.Height) / v),
new PointF(random.Next(rect.Width) / v, rect.Height - random.Next(rect.Height) / v),
new PointF(rect.Width - random.Next(rect.Width) / v, rect.Height - random.Next(rect.Height) / v)
};
Matrix matrix = new Matrix();
matrix.Translate(0F, 0F);
path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
// Draw the text.
hatchBrush = new HatchBrush(HatchStyle.DashedUpwardDiagonal, Color.DarkGray, Color.Black);
g.FillPath(hatchBrush, path);
// Add some random noise.
int m = Math.Max(rect.Width, rect.Height);
for (int i = 0; i < (int)(rect.Width * rect.Height / 30F); i++)
{
int x = random.Next(rect.Width);
int y = random.Next(rect.Height);
int w = random.Next(m / 50);
int h = random.Next(m / 50);
g.FillEllipse(hatchBrush, x, y, w, h);
}
// Clean up.
font.Dispose();
hatchBrush.Dispose();
g.Dispose();
CaptchaMessage message = new CaptchaMessage();
message.RequiredAnswer = text;
message.CaptchaImage = bitmap;
message.CaptchaHash = encryptStr(encryptStr(text, captcahSalt, true) + "$##$" + DateTime.Now.ToString(), captcahSalt, true).Replace("=", "~A");
return message;
}
