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
后端代码：
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
{
/// <summary>
/// 矩形宽
/// </summary>
public static int l = 42;
/// <summary>
/// 圆形半径
/// </summary>
public static int r = 9;
/// <summary>
/// 圆形直径
/// </summary>
public static int d = r * 2;
/// <summary>
/// 计算圆形与矩形交接三角形边
/// </summary>
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;
/// <summary>
/// 滑块边框
/// </summary>
public static int blod = 2;
/// <summary>
/// 水印
/// </summary>
public static string watermarkText = "SC.NET";
/// <summary>
/// 是否显示水印
/// </summary>
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);
}
前端代码：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Splide Captcha</title>
<style>
* {
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
} .sc-captcha {
width: 300px;
margin: 100px auto;
} .sc_net_panel {
padding: 10px;
} .sc_net_panel > div {
position: relative;
} .bg_slider {
position: absolute;
left: 0;
top: 0;
} .bg_refresh {
position: absolute;
right: 5px;
top: 5px;
background: #808080;
color: #fff;
border-radius: 3px;
width: 16px;
line-height: 16px;
text-align: center;
cursor: pointer;
} .sc_net_slider_icon {
position: absolute;
left: 0;
top: 0;
height: 37px;
text-align: center;
border-radius: 5px;
border: #808080 1px solid;
width: 37px;
line-height: 37px;
cursor: pointer;
} .sc_net_slider_icon:hover {
color: #fff;
background: #1991fa;
} .sc_net_slider_text {
position: absolute;
left: 0;
top: 0;
text-align: center;
width: 280px;
color: #45494c;
border: #808080 1px solid;
border-radius: 5px;
line-height: 35px;
height: 37px;
cursor: default;
} .sc_net_slider_area {
position: absolute;
left: 0;
top: 0;
height: 37px;
}
</style>
<script src="E:\porject\碚煜Api\ByzkApi\Scripts\jquery-3.4.1.js"></script>
<script src="E:\porject\碚煜Api\ByzkApi\Scripts\jquery-3.4.1.min.js"></script> </head>
<body>
<div>
<div class="sc-captcha">
<div class="sc_net_panel">
<div class="sc_net_bg">
<div class="sc_net_bgimg">
</div>
<div class="bg_refresh" onclick="loadCaptcha()" title="刷新">↻</div>
</div>
</div>
<div class="sc_net_panel">
<div class="sc_net_slider">
<div class="sc_net_slider_text">向右拖动滑块填充拼图</div>
<div class="sc_net_slider_area"></div>
<div class="sc_net_slider_icon">➞</div>
</div>
</div>
</div>
</div> </body> <script>
loadCaptcha();
function loadCaptcha() {
$.ajax({
url: "http://192.168.1.216:5500/api/TestApi/GetCaptcha",
type: "Get",
dataType: "JSON",
success: function (json) {
var bg = createCanvas(280, 155);
bg.className = 'bg_img';
bg_slider = createCanvas(62, 155);
bg_slider.className = 'bg_slider';
CanvasSetImage(bg, json.background);
CanvasSetImage(bg_slider, json.slider);
var doc = document.getElementsByClassName("sc_net_bgimg")[0];
doc.innerHTML = "";
doc.appendChild(bg);
doc.appendChild(bg_slider); console.log(json.modelX);
}
})
} function createCanvas(width, height) {
var canvas = document.createElement('canvas');
canvas.width = width;
canvas.height = height;
return canvas;
}; function CanvasSetImage(_canvas, base64) { //获取2d画布对象
var ctx = _canvas.getContext("2d");
//创建图片标签
var _img = document.createElement("img");
//设置图片地址
_img.src = base64; //ctx.fillRect(0, 0, _canvas.clientWidth, _canvas.clientHeight);
//ctx.fillStyle = 'rgba(255, 255, 255, 0)';
_img.onload = function () {
ctx.drawImage(_img, 0, 0);
}
/* ctx.drawImage(_img, 10, 10);*/
} function getByClassName0(className) {
return document.getElementsByClassName(className)[0];
}; var slider = getByClassName0("sc_net_slider_icon");
var text = getByClassName0("sc_net_slider_text");
var area = getByClassName0("sc_net_slider_area");
var bg_slider; slider.addEventListener('mousedown', handleDragStart);
slider.addEventListener('touchstart', handleDragStart);
document.addEventListener('mousemove', handleDragMove);
document.addEventListener('touchmove', handleDragMove);
document.addEventListener('mouseup', handleDragEnd);
document.addEventListener('touchend', handleDragEnd);
document.addEventListener('mousedown', function () { return false; });
document.addEventListener('touchstart', function () { return false; }); var originX, originY, trail = [],
isMouseDown = false; var isOk = false; function handleDragStart(e) {
console.log("handleDragStart");
if (isOk) return;
originX = e.clientX || e.touches[0].clientX;
originY = e.clientY || e.touches[0].clientY;
isMouseDown = true;
}; function handleDragMove(e) {
if (!isMouseDown) return false;
var eventX = e.clientX || e.touches[0].clientX;
var eventY = e.clientY || e.touches[0].clientY;
var moveX = eventX - originX;
var moveY = eventY - originY;
if (moveX >= 0 && moveX <= 243) {
slider.style.left = moveX + "px";
bg_slider.style.left = moveX / 243 * 218 + "px";
} }; function handleDragEnd(e) {
if (!isMouseDown)
return false
isMouseDown = false
var eventX = e.clientX || e.changedTouches[0].clientX
if (eventX == originX)
return false //获取前端的x坐标；
var a = $(".bg_slider");
var localX = a[0].offsetLeft; $.ajax({
url: "http://192.168.1.216:5500/api/TestApi/CheckCaptcha?x=" + localX,
type: "Post",
dataType: "JSON",
success: function (res) {
alert(res.Mess);
}
})
};
</script>
</html>
结语：
到这里基本上就已经完成了，以上前端地址更换成自己的接口即可。正常业务 验证码是很频发的一个操作并且是多用户。所以缓存存储的时候也需要注意一下。最后有问题的话，可以评论区沟通。感谢观看！（这次很用心在写，能否上个推荐~）
