mvc 如何生成空心3D风格的验证码
做网站往往少不了要用到图片验证码。虽然现在已经有很多更先进的判断真实用户的手段，但验证码是最基本的一种。
博主要介绍一种用C#生成空心风格验证码的最简单方法，哈哈，真的很简单哦。说来以前我看到腾讯的空心字验证码也是很流口水啊,比默认字体的漂亮太多了，无奈工作太忙一直没有时间尝试，有一些偶然被设计MM提醒了一下，茅塞顿开呀。
实现方法：这里要用到.net framework里面的一个类：PrivateFontCollection,直观的翻成中文就是私有字体集合，msdn上的解释是：
“提供一个字体系列集合，该集合是基于客户端应用程序提供的字体文件生成的。“
也就是说可以在程序中使用自己的字体，那么能不能可web程序 中使用呢，呵呵，当然可以了.
下面就跟博主一步步来实现吧
1、创建一个类，CaptchaController，继承自Controller,返回图片的方法为Show
public class CaptchaController : Controller
{
//
// GET: /Captcha/
public ActionResult Show(int? len, int? w,int? h)
{
}
}接下来添加两个私有成员
PrivateFontCollection privateFontCollection = new PrivateFontCollection();
FontFamily[] _families = { };PrivateFontCollection将为我们加载空心字体
2、下载空心字体，引入到代码中，到哪里去下载呢，当然是百度了，不过博主是找公司的设计MM要的，毕竟她们整天接触这个，下面是博主找到的三个空心字体文件，可以把它们放在app_data文件夹里。
接下来直接引用到代码中
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/swisscbo.ttf"));
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/LARSON.TTF"));
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/AgentRed.TTF"));
//new FontFamily("Acidic"),
// new FontFamily("Rosewood Std"),
_families = privateFontCollection.Families;3、生成随机码，方法如下
private string RandomCode(int count)
{
Random rand = new Random((int)now.Ticks / 20000);
String allChar = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
Char[] allCharArray = allChar.ToCharArray();
String randomCode = "";
for (int i = 0; i < count; i++)
{
int t = rand.Next(35);
randomCode = String.Concat(randomCode, Char.ToString(allCharArray[t]));
}
return randomCode;
}4、开始画图，代码如下
public Bitmap GenerateImage(string text, Size size)
{
VXin.Core.RandomNumbers rand = new VXin.Core.RandomNumbers();
// Create the new Bitmap of the specified size and render to it
Bitmap bmp = new Bitmap(size.Width, size.Height);
using (Graphics g = Graphics.FromImage(bmp))
{
g.SmoothingMode = SmoothingMode.AntiAlias; //使绘图质量最高，即消除锯齿
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
//Draw the background with a white brush
using (Brush b = new SolidBrush(Color.FromArgb(0xec, 0xf8, 0xff)))
{
g.FillRectangle(b, 0, 0, bmp.Width, bmp.Height);
}
// Select a font family and create the default sized font. We then need to shrink
// the font size until the text fits.
FontFamily ff = _families[rand.Next(_families.Length)];
int emSize = (int)(size.Width * 2.5 / text.Length);
Font f = new Font(ff, emSize);
try
{
// Make sure that the font size we have will fit with the selected text.
SizeF measured = new SizeF(0, 0);
SizeF workingSize = new SizeF(size.Width, size.Height);
while (emSize > 2 &&
(measured = g.MeasureString(text, f)).Width > workingSize.Width ||
measured.Height > workingSize.Height)
{
f.Dispose();
f = new Font(ff, emSize -= 2, FontStyle.Bold);
}
// Select a color and draw the string into the center of the image
using (StringFormat fmt = new StringFormat())
{
fmt.Alignment = fmt.LineAlignment = StringAlignment.Center;
using (Brush b = new LinearGradientBrush(
new Rectangle(0, 0, size.Width / 2, size.Height / 2),
_colors[rand.Next(_colors.Length)],
_colors[rand.Next(_colors.Length)],
(float)(rand.NextDouble() * 360), false))
{
g.DrawString(text, f, b, new Rectangle(0, 5, bmp.Width, bmp.Height), fmt);
}
}
}
finally
{
// Clean up
f.Dispose();
}
}
return bmp;
}5、到这里画图这一步就完成了，输入应该是一个比较规整的显示字母的图片，但这是不是我想要的验证码啊，验证码不是防止机器识别的吗,不要急，接下来通过最后一步，使图片扭曲，如何扭曲呢，博主打算给它来个波浪型变幻，也就是正弦变幻啦，怎么做到呢，呵呵，用笨方法，挪动每个相素的位置，大家如果有好的办法也可以在下面留言，代码如下
private static void DistortImage(Bitmap b, double distortion)
{
int width = b.Width, height = b.Height;
// Copy the image so that we‘re always using the original for source color
using (Bitmap copy = (Bitmap)b.Clone())
{
// Iterate over every pixel
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
// Adds a simple wave
int newX = (int)(x + (distortion * Math.Sin(Math.PI * y / 64.0)));
int newY = (int)(y + (distortion * Math.Cos(Math.PI * x / 64.0)));
if (newX < 0 || newX >= width) newX = 0;
if (newY < 0 || newY >= height) newY = 0;
b.SetPixel(x, y, copy.GetPixel(newX, newY));
}
}
}
}
6、完整代码
public class CaptchaController : Controller
{
//
// GET: /Captcha/
public ActionResult Show(int? len, int? w,int? h)
{
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/swisscbo.ttf"));
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/LARSON.TTF"));
privateFontCollection.AddFontFile(Server.MapPath("/App_Data/AgentRed.TTF"));
_families = privateFontCollection.Families;
if (!len.HasValue)
len = 5;
var code = RandomCode(len);
var bmpOut = GenerateImage(code, new Size(90, 42));
var ms = new MemoryStream();
bmpOut.Save(ms, ImageFormat.Png);
var bmpBytes = ms.GetBuffer();
bmpOut.Dispose();
ms.Close();
privateFontCollection.Dispose();
Session["Captcha"] = code;
return File(bmpBytes, @"image/jpeg");
}
/// <summary>Generates the challenge image.</summary>
/// <param name="text">The text to be rendered into the image.</param>
/// <param name="size">The size of the image to generate.</param>
/// <returns>A dynamically-generated challenge image.</returns>
public Bitmap GenerateImage(string text, Size size)
{
VXin.Core.RandomNumbers rand = new VXin.Core.RandomNumbers();
// Create the new Bitmap of the specified size and render to it
Bitmap bmp = new Bitmap(size.Width, size.Height);
using (Graphics g = Graphics.FromImage(bmp))
{
g.SmoothingMode = SmoothingMode.AntiAlias; //使绘图质量最高，即消除锯齿
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.CompositingQuality = CompositingQuality.HighQuality;
//Draw the background with a white brush
using (Brush b = new SolidBrush(Color.FromArgb(0xec, 0xf8, 0xff)))
{
g.FillRectangle(b, 0, 0, bmp.Width, bmp.Height);
}
// Select a font family and create the default sized font. We then need to shrink
// the font size until the text fits.
FontFamily ff = _families[rand.Next(_families.Length)];
int emSize = (int)(size.Width * 2.5 / text.Length);
Font f = new Font(ff, emSize);
try
{
// Make sure that the font size we have will fit with the selected text.
SizeF measured = new SizeF(0, 0);
SizeF workingSize = new SizeF(size.Width, size.Height);
while (emSize > 2 &&
(measured = g.MeasureString(text, f)).Width > workingSize.Width ||
measured.Height > workingSize.Height)
{
f.Dispose();
f = new Font(ff, emSize -= 2, FontStyle.Bold);
}
// Select a color and draw the string into the center of the image
using (StringFormat fmt = new StringFormat())
{
fmt.Alignment = fmt.LineAlignment = StringAlignment.Center;
using (Brush b = new LinearGradientBrush(
new Rectangle(0, 0, size.Width / 2, size.Height / 2),
_colors[rand.Next(_colors.Length)],
_colors[rand.Next(_colors.Length)],
(float)(rand.NextDouble() * 360), false))
{
g.DrawString(text, f, b, new Rectangle(0, 5, bmp.Width, bmp.Height), fmt);
}
}
}
finally
{
// Clean up
f.Dispose();
}
}
// Distort the final image and return it. This distortion amount is fairly arbitrary.
DistortImage(bmp, rand.Next(5, 10) * (rand.Next(2) == 1 ? 1 : -1));
using (Graphics g = Graphics.FromImage(bmp))
{
using (var pen = new Pen(Color.FromArgb(0xd7, 0xed, 0xfa)))
{
g.DrawRectangle(pen, new Rectangle(0, 0, bmp.Width - 1, bmp.Height - 1));
}
}
return bmp;
}
/// <summary>Distorts the image.</summary>
/// <param name="b">The image to be transformed.</param>
/// <param name="distortion">An amount of distortion.</param>
private static void DistortImage(Bitmap b, double distortion)
{
int width = b.Width, height = b.Height;
// Copy the image so that we‘re always using the original for source color
using (Bitmap copy = (Bitmap)b.Clone())
{
// Iterate over every pixel
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
// Adds a simple wave
int newX = (int)(x + (distortion * Math.Sin(Math.PI * y / 64.0)));
int newY = (int)(y + (distortion * Math.Cos(Math.PI * x / 64.0)));
if (newX < 0 || newX >= width) newX = 0;
if (newY < 0 || newY >= height) newY = 0;
b.SetPixel(x, y, copy.GetPixel(newX, newY));
}
}
}
}
private string RandomCode(int count)
{
Random rand = new Random((int)now.Ticks / 20000);
String allChar = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
Char[] allCharArray = allChar.ToCharArray();
String randomCode = "";
for (int i = 0; i < count; i++)
{
int t = rand.Next(35);
randomCode = String.Concat(randomCode, Char.ToString(allCharArray[t]));
}
return randomCode;
}
private static Color[] _colors = {
Color.ForestGreen,
Color.FromArgb(0,68, 0xA3),
Color.FromArgb(10, 0x1f, 28),
Color.FromArgb(0xe8, 0,0),
Color.FromArgb(84, 0x0b, 0x0b),
Color.FromArgb(0x1f, 84, 0x0b),
Color.FromArgb(11, 65, 01),
Color.FromArgb(79, 0x2c, 0x8f),
Color.FromArgb(0x0d, 01, 65)
};
/// <summary>List of fonts that can be used for rendering text.</summary>
/// <remarks>This list can be changed to include any families available on the current system.</remarks>
PrivateFontCollection privateFontCollection = new PrivateFontCollection();
private FontFamily[] _families = { };
}好了，现在可以把这段程序应用到自己网站上了，刷新一下，显示的应该是这样
以及这样
每次显示的曲线都不一样哦，还是空心3D字体，看上去是不是很拉轰呢
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