// Make a captcha image for the text.
public Bitmap MakeCaptchaImge(string txt,
int min_size, int max_size, int wid, int hgt, CaptchaStyle cStyle = CaptchaStyle.TextWithLineAndCircles)
{
// Make the bitmap and associated Graphics object.
Bitmap bm = new Bitmap(wid, hgt);
using (Graphics gr = Graphics.FromImage(bm))
{
gr.SmoothingMode = SmoothingMode.HighQuality;
gr.Clear(Color.LightYellow);
var r = new Random();
if (cStyle == CaptchaStyle.TextWithLineAndCircles)
{
for (int i = 0; i < 10; i++)
{
var s = r.Next(10, 15);
gr.DrawEllipse(new Pen(Color.SandyBrown, 2), r.Next(5, wid), r.Next(5, hgt), s, s);
}
}
// See how much room is available for each character.
int ch_wid = (int)(wid / txt.Length);
// Draw each character.
for (int i = 0; i < txt.Length; i++)
{
float font_size = Rand.Next(min_size, max_size);
using (Font the_font = new Font("Times New Roman",
font_size, FontStyle.Bold))
{
DrawCharacter(txt.Substring(i, 1), gr,
the_font, i * ch_wid, ch_wid, wid, hgt);
}
}
if (cStyle == CaptchaStyle.TextWithLineAndCircles || cStyle == CaptchaStyle.TextWithLine)
{
var points = new List <PointF>();
for (int i = 0; i < 7; i++)
{
var x = r.Next(0, wid);
var y = r.Next(0, hgt);
points.Add(new PointF(x, y));
}
gr.DrawCurve(new Pen(Color.LightGray, 3), points.ToArray());
}
}
return(bm);
}
// Methods
internal static bool ParseDistorsionParam(NameValueCollection parameters, out CaptchaStyle distStyle)
{
if ((null != parameters) && !string.IsNullOrEmpty(parameters[CaptchaImageTransformation.DISTSTYLE_KEY]))
{
distStyle = (CaptchaStyle)Enum.Parse(typeof(CaptchaStyle), parameters[CaptchaImageTransformation.DISTSTYLE_KEY]);
if (CaptchaStyle.Random == distStyle)
{
distStyle = (CaptchaStyle)new Random(DateTime.Now.Millisecond).Next(3);
}
return true;
}
else
{
distStyle = CaptchaStyle.Confetti;
return false;
}
}
// Methods
internal static string ToQueryString(
int width,
int height,
int clientCacheDuration,
int serverCacheDuration,
RotateFlipType rotateFlip,
bool drawGrayscale,
bool drawSepia,
DynamicText text,
DynamicImageFormat imageFormat,
KeyValuePair<Type, IDictionary<string, string>>? imageCreator,
Dictionary<Type, IDictionary<string, string>> imageTransformations,
TextContainerSizeType sizeType,
CaptchaStyle distortionStyle,
ReadnessLevel readnessLevel,
Color backColor)
{
string dynamicImageQueryString = DynamicImageProvider.ToQueryString(
null,
width,
height,
clientCacheDuration,
serverCacheDuration,
rotateFlip,
drawGrayscale,
drawSepia,
text,
imageFormat,
imageCreator,
imageTransformations);
List<string> parameters = new List<string>();
string parameterFormat = "{0}={1}";
// size type
if (TextContainerSizeType.Specified != sizeType)
{
parameters.Add(string.Format(parameterFormat, TextDependentImageCreator.TEXTCONTSIZETYPE_KEY, sizeType));
}
// distortion style
if (CaptchaStyle.Confetti != distortionStyle)
{
parameters.Add(string.Format(parameterFormat, CaptchaImageTransformation.DISTSTYLE_KEY, distortionStyle));
}
// readness level
if (ReadnessLevel.Normal != readnessLevel)
{
parameters.Add(string.Format(parameterFormat, CaptchaImageTransformation.READLEVEL_KEY, readnessLevel));
}
// back color
if (Color.White != backColor)
{
parameters.Add(string.Format(parameterFormat, CaptchaImageTransformation.CAPTCHABACKCOLOR_KEY, backColor.ToArgb()));
}
return (0 < parameters.Count) ? string.Concat(dynamicImageQueryString, "&", string.Join("&", parameters.ToArray())) : dynamicImageQueryString;
}
