本文实例讲述了winform生成验证码图片的方法。分享给大家供大家参考，具体如下：
1、创建validcode类：
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public class validcode
{
#region private fields
private const double pi = 3.1415926535897932384626433832795;
private const double pi2 = 6.283185307179586476925286766559;
//private readonly int _wordslen = 4;
private int _len;
private codetype _codetype;
private readonly single _jianju = (float)18.0;
private readonly single _height = (float)24.0;
private string _checkcode;
#endregion
#region public property
public string checkcode
{
get
{
return _checkcode;
}
}
#endregion
#region constructors
/// <summary>
/// public constructors
/// </summary>
/// <param name="len"> 验证码长度 </param>
/// <param name="ctype"> 验证码类型：字母、数字、字母+ 数字 </param>
public validcode(int len, codetype ctype)
{
this._len = len;
this._codetype = ctype;
}
#endregion
#region public field
public enum codetype { words, numbers, characters, alphas }
#endregion
#region private methods
private string generatenumbers()
{
string strout = "";
system.random random = new random();
for (int i = 0; i < _len; i++)
{
string num = convert.tostring(random.next(10000) % 10);
strout += num;
}
return strout.trim();
}
private string generatecharacters()
{
string strout = "";
system.random random = new random();
for (int i = 0; i < _len; i++)
{
string num = convert.tostring((char)(65 + random.next(10000) % 26));
strout += num;
}
return strout.trim();
}
//
private string generatealphas()
{
string strout = "";
string num = "";
system.random random = new random();
for (int i = 0; i < _len; i++)
{
if (random.next(500) % 2 == 0)
{
num = convert.tostring(random.next(10000) % 10);
}
else
{
num = convert.tostring((char)(65 + random.next(10000) % 26));
}
strout += num;
}
return strout.trim();
}
private system.drawing.bitmap twistimage(bitmap srcbmp, bool bxdir, double dmultvalue, double dphase)
{
system.drawing.bitmap destbmp = new bitmap(srcbmp.width, srcbmp.height);
// 将位图背景填充为白色
system.drawing.graphics graph = system.drawing.graphics.fromimage(destbmp);
graph.fillrectangle(new solidbrush(system.drawing.color.white), 0, 0, destbmp.width, destbmp.height);
graph.dispose();
double dbaseaxislen = bxdir ? (double)destbmp.height : (double)destbmp.width;
for (int i = 0; i < destbmp.width; i++)
{
for (int j = 0; j < destbmp.height; j++)
{
double dx = 0;
dx = bxdir ? (pi2 * (double)j) / dbaseaxislen : (pi2 * (double)i) / dbaseaxislen;
dx += dphase;
double dy = math.sin(dx);
// 取得当前点的颜色
int noldx = 0, noldy = 0;
noldx = bxdir ? i + (int)(dy * dmultvalue) : i;
noldy = bxdir ? j : j + (int)(dy * dmultvalue);
system.drawing.color color = srcbmp.getpixel(i, j);
if (noldx >= 0 && noldx < destbmp.width
&& noldy >= 0 && noldy < destbmp.height)
{
destbmp.setpixel(noldx, noldy, color);
}
}
}
return destbmp;
}
#endregion
#region public methods
public stream createcheckcodeimage()
{
string checkcode;
switch (_codetype)
{
case codetype.alphas:
checkcode = generatealphas();
break;
case codetype.numbers:
checkcode = generatenumbers();
break;
case codetype.characters:
checkcode = generatecharacters();
break;
default:
checkcode = generatealphas();
break;
}
this._checkcode = checkcode;
memorystream ms = null;
//
if (checkcode == null || checkcode.trim() == string.empty)
return null;
bitmap image = new system.drawing.bitmap((int)math.ceiling((checkcode.length * _jianju)), (int)_height);
graphics g = graphics.fromimage(image);
try
{
random random = new random();
g.clear(color.white);
// 画图片的背景噪音线
for (int i = 0; i < 18; i++)
{
int x1 = random.next(image.width);
int x2 = random.next(image.width);
int y1 = random.next(image.height);
int y2 = random.next(image.height);
g.drawline(new pen(color.fromargb(random.next()), 1), x1, y1, x2, y2);
}
font font = new system.drawing.font("times new roman", 14, system.drawing.fontstyle.bold);
lineargradientbrush brush = new lineargradientbrush(new rectangle(0, 0, image.width, image.height), color.blue, color.darkred, 1.2f, true);
if (_codetype != codetype.words)
{
for (int i = 0; i < checkcode.length; i++)
{
g.drawstring(checkcode.substring(i, 1), font, brush, 2 + i * _jianju, 1);
}
}
else
{
g.drawstring(checkcode, font, brush, 2, 2);
}
// 画图片的前景噪音点
for (int i = 0; i < 150; i++)
{
int x = random.next(image.width);
int y = random.next(image.height);
image.setpixel(x, y, color.fromargb(random.next()));
}
// 画图片的波形滤镜效果
if (_codetype != codetype.words)
{
image = twistimage(image, true, 3, 1);
}
// 画图片的边框线
g.drawrectangle(new pen(color.silver), 0, 0, image.width - 1, image.height - 1);
ms = new system.io.memorystream();
image.save(ms, system.drawing.imaging.imageformat.gif);
}
finally
{
g.dispose();
image.dispose();
}
return ms;
}
#endregion
}
2、产生验证码图片代码：
//参数一：产生几个字符的验证码图片 参数二：验证码的形式(数字、字母、数字字母混合都有) validcode validcode = new validcode(5, validcode.codetype.alphas); this.picturebox2.image = bitmap.fromstream(validcode.createcheckcodeimage());
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