C# 滑动验证码|拼图验证|SlideCaptcha
使用背景：
关于滑动验证码的使用场所还是非常多的，如： 调取短信接口之前，和 注册请求之前 或者 频繁会调用的接口 都需要加这个拼图验证。这里先上一下效果图吧（心中无码，自然高清）。
话不多说，开撸！
实现分析：
滑动验证码的逻辑也很简单。大概说一下：
1，服务器生成主图+附图（从主图裁剪下来的不需要管y坐标）并且存储X坐标；
2，前端传入本地X坐标到服务器。
3，服务器进行计算存储X坐标和本地X坐标相差值；
4，验证相差值是否在 0-2 之间，判断 true | false
准备：
增加SlideCaptcha文件夹，并且增加Captcha.cs CaptchaModel.cs Config.cs ImgFormat.cs 4个文件。分别是：验证，验证实体，配置和图片生成类。代码如下：
Captcha.cs
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Net;
namespace SliderCaptcha.NET
{
public class Captcha
{
public static Captcha64Model GenerateBase64()
{
CaptchaModel model = Captcha.Generate();
if (model != null)
{
return new Captcha64Model()
{
X = model.X,
Y = model.Y,
Background = ImageToBase64(model.Background,ImageFormat.Jpeg),
Slide = ImageToBase64(model.Slide, ImageFormat.Png)
};
}
else
{
return null;
}
}
/// <summary>
/// 生成验证码
/// </summary>
/// <returns></returns>
public static CaptchaModel Generate()
{
Bitmap image = BgImage();
if (image != null)
{
int l = Config.l;
int d = Config.d;
int width = image.Width;
int height = image.Height;
int x = RandomNext(width / 3, width - d - l - 10);//初始x
int y = RandomNext(10 + d, height - l - 10); ;//初始y
GraphicsPath path = GetSliderPath(x, y);
Graphics g = GetGraphics(image);
//水印
if (Config.showWatermark)
{
Font font = new Font("宋体", 12, FontStyle.Bold);
SizeF size = g.MeasureString(Config.watermarkText, font);
Point Plogo = new Point((int)(width - size.Width - 5), (int)(height - size.Height - 5));
Color color = image.GetPixel(Plogo.X, Plogo.Y);
SolidBrush bru = new SolidBrush(AntiColor(color));
g.DrawString(Config.watermarkText, font, bru, Plogo);
}
Pen pen = new Pen(Color.FromArgb(200, 255, 255, 255), 2);
g.DrawPath(pen, path);
Image slider = CaptureSlider(image, path, x, width, height);
SolidBrush brush = new SolidBrush(Color.FromArgb(100, 255, 255, 255));
g.FillPath(brush, path);
g.Save();
g.Dispose();
return new CaptchaModel()
{
X = x,
Y = y,
Background = image,
Slide = slider
};
}
return null;
}
/// <summary>
/// 获取图片Graphics
/// </summary>
/// <param name="image"></param>
/// <returns></returns>
private static Graphics GetGraphics(Image image)
{
Graphics g = Graphics.FromImage(image);
g.SmoothingMode = SmoothingMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.InterpolationMode = InterpolationMode.High;
return g;
}
/// <summary>
/// 获取滑块path
/// </summary>
private static GraphicsPath GetSliderPath(int x, int y)
{
int l = Config.l;
int r = Config.r;
int b = Config.b;
int c = Config.c;
int d = Config.d;
int blod = Config.blod;
GraphicsPath path = new GraphicsPath(FillMode.Winding);
Point Pa = new Point(x, y);
Point Pb = new Point(x + l / 2 - b, y - c + blod);
Point Pd = new Point(x + l, y);
Point Pe = new Point(Pd.X + c - blod, y + l / 2 - b);
Point Pg = new Point(Pd.X, y + l);
Point Ph = new Point(x, y + l);
Point Pj = new Point(x + c - blod, Pe.Y);
path.AddLine(Pa, Pb);
path.AddArc(x + l / 2 - r, y - d, d, d, 130f, 280f);
path.AddLines(new Point\[\] { Pd, Pe });
path.AddArc(x + l, y + l / 2 - r, d, d, 220f, 280f);
path.AddLines(new Point\[\] { Pg, Ph });
path.AddArc(x, y + l / 2 - r, d, d, 140f, -280f);
path.AddLine(Pj, Pa);
return path;
}
/// <summary>
/// 获取滑块区域
/// </summary>
/// <param name="image"></param>
/// <param name="path"></param>
/// <param name="x"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <returns></returns>
private static Image CaptureSlider(Image image, GraphicsPath path, int x, int width, int height)
{
Bitmap concave = new Bitmap(image.Width, image.Height);
Graphics g = GetGraphics(concave);
TextureBrush brush = new TextureBrush(image);
g.Clear(Color.Transparent);
g.FillPath(brush, path);
g.Dispose();
return CaptureImage(concave, x, height);
}
/// <summary>
/// 裁剪图片
/// </summary>
/// <param name="fromImage"></param>
/// <param name="offsetX"></param>
/// <param name="width"></param>
/// <param name="height"></param>
/// <returns></returns>
private static Image CaptureImage(Image fromImage, int offsetX, int height)
{
int width = Config.l + Config.d + Config.blod;
Bitmap bitmap = new Bitmap(width, height);
Graphics g = GetGraphics(bitmap);
g.DrawImage(fromImage, 0, 0, new Rectangle(offsetX, 0, width, height), GraphicsUnit.Pixel);
g.Dispose();
return bitmap;
}
/// <summary>
/// 生成随机数
/// </summary>
/// <param name="min"></param>
/// <param name="max"></param>
/// <returns></returns>
private static int RandomNext(int min, int max)
{
Random random = new Random(Guid.NewGuid().GetHashCode());
return random.Next(min, max);
}
/// <summary>
/// 取反色
/// </summary>
/// <param name="color"></param>
/// <returns></returns>
public static Color AntiColor(Color color)
{
if (color.R > 128 && color.G > 128 && color.B > 128)
{
return Color.Black;
}
else
{
return Color.White;
}
}
/// <summary>
/// 获取背景图
/// </summary>
/// <returns></returns>
private static Bitmap BgImage()
{
WebClient web = new WebClient();
int num = RandomNext(1, 20);
Stream stream = web.OpenRead($"http://00x1.com/images/Pic/{num}.jpg");
Bitmap bitmap = (Bitmap)Image.FromStream(stream);
return bitmap;
}
/// <summary>
/// base64转图片
/// </summary>
/// <param name="base64string"></param>
/// <returns></returns>
public static Bitmap Base64ToImage(string base64string)
{
byte\[\] b = Convert.FromBase64String(base64string);
MemoryStream ms = new MemoryStream(b);
Bitmap bitmap = new Bitmap(ms);
return bitmap;
}
/// <summary>
/// 图片转base64
/// </summary>
/// <param name="image"></param>
/// <returns></returns>
public static string ImageToBase64(Image image, ImageFormat format)
{
if (image == null) return string.Empty;
string strbaser64 = "";
try
{
string head = "";
string formatName = ImgFormat.NameFromGuid(format);
head = $"data:image/{formatName.ToLower()};base64,";
MemoryStream ms = new MemoryStream();
image.Save(ms, format);
byte\[\] arr = new byte\[ms.Length\];
ms.Position = 0;
ms.Read(arr, 0, (int)ms.Length);
ms.Close();
strbaser64 = head+Convert.ToBase64String(arr);
}
catch (Exception)
{
throw new Exception("Something wrong during convert!");
}
return strbaser64;
}
}}
CaptchaModel.cs
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
namespace SliderCaptcha.NET
{
public class CaptchaModel
{
public int X { get; set; }
public int Y { get; set; }
public Image Background { get; set; }
public Image Slide { get; set; }
}
public class Captcha64Model
{
public int X { get; set; }
public int Y { get; set; }
public string Background { get; set; }
public string Slide { get; set; }
}
}
Config.cs
using System;
namespace SliderCaptcha.NET
{
public class Config
{
///
public static int l = 42;
///
public static int r = 9;
///
public static int d = r * 2;
///
public static int a = (int)(r * Math.Sin(Math.PI * (50 / 180f)));
public static int b = (int)(r * Math.Cos(Math.PI * (50 / 180f)));
public static int c = r - a;
///
public static int blod = 2;
///
public static string watermarkText = "SC.NET";
///
public static bool showWatermark = true;
} }
ImgFormat.cs
using System;
using System.Collections.Generic;
using System.Drawing.Imaging;
namespace SliderCaptcha.NET
{
public class ImgFormat
{
private static Dictionary<string, string> Formats = new Dictionary<string, string>() {
{"b96b3caa-0728-11d3-9d7b-0000f81ef32e","MemoryBmp"},
{"b96b3cab-0728-11d3-9d7b-0000f81ef32e","Bmp"},
{"b96b3cac-0728-11d3-9d7b-0000f81ef32e","Emf"},
{"b96b3cad-0728-11d3-9d7b-0000f81ef32e","Wmf"},
{"b96b3cae-0728-11d3-9d7b-0000f81ef32e","Jpeg"},
{"b96b3caf-0728-11d3-9d7b-0000f81ef32e","Png"},
{"b96b3cb0-0728-11d3-9d7b-0000f81ef32e","Gif"},
{"b96b3cb1-0728-11d3-9d7b-0000f81ef32e","Tiff"},
{"b96b3cb2-0728-11d3-9d7b-0000f81ef32e","Exif"},
{"b96b3cb5-0728-11d3-9d7b-0000f81ef32e","Icon"}
};
public static ImageFormat FormatFromGuid(ImageFormat format)
{
return FormatFromGuid(format.Guid);
}
public static ImageFormat FormatFromGuid(Guid guid)
{
return FormatFromGuid(guid.ToString());
}
public static ImageFormat FormatFromGuid(string guid)
{
if (Formats.ContainsKey(guid))
{
string name = Formats\[guid\];
ImageFormat format = null;
switch (name)
{
case "MemoryBmp":
format = ImageFormat.MemoryBmp;
break;
case "Bmp":
format = ImageFormat.Bmp;
break;
case "Emf":
format = ImageFormat.Emf;
break;
case "Wmf":
format = ImageFormat.Wmf;
break;
case "Gif":
format = ImageFormat.Gif;
break;
case "Jpeg":
format = ImageFormat.Jpeg;
break;
case "Png":
format = ImageFormat.Png;
break;
case "Tiff":
format = ImageFormat.Tiff;
break;
case "Exif":
format = ImageFormat.Exif;
break;
case "Icon":
format = ImageFormat.Icon;
break;
}
return format;
}
else
{
return null;
}
}
public static string NameFromGuid(ImageFormat format)
{
return NameFromGuid(format.Guid);
}
public static string NameFromGuid(Guid guid)
{
return NameFromGuid(guid.ToString());
}
public static string NameFromGuid(string guid)
{
if (Formats.ContainsKey(guid))
{
return Formats\[guid\];
}
else
{
return string.Empty;
}
}
} }
使用：
这里用的是asp.net mvc 的框架，用的是api接口，前后端分离供前端使用。具体使用根据个人需求，可以是接口调用亦可以是项目调用。
呼声如果很高的话，考虑出一个winfrom版本的滑动验证码~（滑稽）
\[HttpGet\]
public IHttpActionResult GetCaptcha()
{
Captcha64Model model = Captcha.GenerateBase64();
CacheHelper.Cache.SetCache("sliderX", model.X);
Hashtable ht = new Hashtable();
ht.Add("background", model.Background);
ht.Add("slider", model.Slide);
ht.Add("sliderXXXXX", model.X);
return Json(ht);
}
/// <summary>
/// 检查验证
/// </summary>
/// <param name="x"></param>
/// <returns></returns>
\[HttpPost\]
public IHttpActionResult CheckCaptcha(\[FromBody\] int x = 0)
{
Hashtable hs = new Hashtable();
string Mess = "";
int Code = 0;
var session = CacheHelper.Cache.GetCache("sliderX");
if (session == null)
{
Mess = "请刷新验证码";
Code = 500;
goto block;
}
string sliderXStr = session?.ToString();// as string
int sliderX = Convert.ToInt32(sliderXStr);
int difX = sliderX - x;
if (difX >= 0 - Config.blod && difX <= Config.blod)
{
Mess = "success";
Code = 0;
}
else
{
session = null;
Mess = "错误";
Code = 500;
}
block:
hs.Add("Mess", Mess);
hs.Add("Code", Code);
return Json(hs);
}