protected virtual string GenerateRandomText()
{
string referenceChars = CaptchaCharacters;
int length = CaptchaLength;
var stringBuilder = new StringBuilder(length);
for (int index = 0; index <= length - 1; ++index)
{
stringBuilder.Append(referenceChars.Substring(CryptoRandomNumberUtil.GetInt32(0, referenceChars.Length - 1), 1));
}
return(stringBuilder.ToString());
}
/// <summary>
/// Add a variable level of graphic noise to the image
///
/// </summary>
private void AddNoise(Graphics graphics1, Rectangle rect)
{
int num1 = 0;
int num2 = 0;
switch (BackgroundNoise)
{
case BackgroundNoiseLevel.None:
return;
case BackgroundNoiseLevel.Low:
num1 = 30;
num2 = 40;
break;
case BackgroundNoiseLevel.Medium:
num1 = 18;
num2 = 40;
break;
case BackgroundNoiseLevel.High:
num1 = 16;
num2 = 39;
break;
case BackgroundNoiseLevel.Extreme:
num1 = 12;
num2 = 38;
break;
}
using (var solidBrush = new SolidBrush(NoiseColor))
{
int maxValue = Convert.ToInt32(Math.Max(rect.Width, rect.Height) / num2);
for (int index = 0; index <= Convert.ToInt32(rect.Width * rect.Height / num1); ++index)
{
graphics1.FillEllipse(solidBrush,
CryptoRandomNumberUtil.GetInt32(0, rect.Width),
CryptoRandomNumberUtil.GetInt32(0, rect.Height),
CryptoRandomNumberUtil.GetInt32(0, maxValue),
CryptoRandomNumberUtil.GetInt32(0, maxValue));
}
}
}
/// <summary>
/// Returns a random point within the specified x and y ranges
/// </summary>
private PointF RandomPoint(int xmin, int xmax, int ymin, int ymax)
{
return(new PointF(CryptoRandomNumberUtil.GetInt32(xmin, xmax), CryptoRandomNumberUtil.GetInt32(ymin, ymax)));
}
/// <summary>
/// Returns a random font family from the font whitelist
///
/// </summary>
private string RandomFontFamily()
{
string[] strArray = FontWhitelist.Split(';');
return(strArray[CryptoRandomNumberUtil.GetInt32(0, strArray.Length - 1)]);
}
