推荐使用SkiaSharp
首先，安装SkiaSharp
编写好图形生成代码。
在windows 上简易代码
using SkiaSharp;
using System.Drawing;
using System.Drawing.Text;
namespace VertifyCode
{
public class VerifyCodeHelper
{
private static readonly char[] Chars = { '0','1','2','3','4','5','6','8','9',
'A','B','C','D','E','F','G','H','I','J','K', 'L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z' };
//private static readonly int Width = 90;
//private static readonly int Height = 35;
private static string GenCode(int num)
{
var code = string.Empty;
var r = new Random();
for (int i = 0; i < num; i++)
{
code += Chars[r.Next(Chars.Length)].ToString();
}
return code;
}
/// <summary>
/// 获取图像数字验证码
/// </summary>
/// <returns></returns>
public static (string code, byte[] bytes) GetVerifyCode()
{
var code = GenCode(4);
int width = 128;
int height = 45;
Random random = new();
//创建bitmap位图
using SKBitmap image = new(width, height, SKColorType.Bgra8888, SKAlphaType.Premul);
//创建画笔
using SKCanvas canvas = new(image);
//填充背景颜色为白色
canvas.DrawColor(SKColors.White);
//画图片的背景噪音线
for (int i = 0; i < (width * height * 0.015); i++)
{
using SKPaint drawStyle = new();
drawStyle.Color = new(Convert.ToUInt32(random.Next(Int32.MaxValue)));
canvas.DrawLine(random.Next(0, width), random.Next(0, height), random.Next(0, width), random.Next(0, height), drawStyle);
}//将文字写到画布上
using (SKPaint drawStyle = new())
{
drawStyle.Color = SKColors.Red;
drawStyle.TextSize = height;
drawStyle.StrokeWidth = 1;
float emHeight = height - (float)height * (float)0.14;
float emWidth = ((float)width / code.Length) - ((float)width * (float)0.13);
canvas.DrawText(code, emWidth, emHeight, drawStyle);
}
//画图片的前景噪音点
for (int i = 0; i < (width * height * 0.15); i++)
{
image.SetPixel(random.Next(0, width), random.Next(0, height), new SKColor(Convert.ToUInt32(random.Next(Int32.MaxValue))));
}
using var img = SKImage.FromBitmap(image);
using SKData p = img.Encode(SKEncodedImageFormat.Png, 100);
return (code, p.ToArray());
}
}
}
以上代码docker 不可用，如果需要在linux 上课用，还需要下载SkiaSharp.linux,【SkiaSharp.NativeAssets.Linux.NoDependencies】本篇着重讲在docker 环境下的使用，兼容非docker 容器
在docker 下使用的话需要使用外部字体
[HttpGet]
public FileContentResult Get()
{
string code;
var img = Create(out code);
// Console.WriteLine(code);
HttpContext.Session.SetString("code", code);
//GC.Collect();
return File(img.ToArray(), "image/png");
}
private static string RndNum(int VcodeNum)
{
//验证码可以显示的字符集合
string Vchar = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,m,n,p" +
",q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q" +
",R,S,T,U,V,W,X,Y,Z";
string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组
string code = "";//产生的随机数
int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数
Random rand = new Random();
//采用一个简单的算法以保证生成随机数的不同
for (int i = 1; i < VcodeNum + 1; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化随机类
}
int t = rand.Next(58);//获取随机数
if (temp != -1 && temp == t)
{
return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用
}
temp = t;//把本次产生的随机数记录起来
code += VcArray[t];//随机数的位数加一
}
return code;
}
public static MemoryStream Create(out string code, int numbers = 4)
{
code = RndNum(numbers);
MemoryStream ms = new MemoryStream();
Random random = new Random();
int width = 72;
int height = 32;
var bitmap = new SKBitmap(width, height);
using (var canvas = new SKCanvas(bitmap))
{
canvas.Clear(SKColors.White);
using (var paint = new SKPaint())
{
// 绘制干扰线
paint.Color = SKColors.LightGray;
paint.StrokeWidth = 2;
for (int i = 0; i < 5; i++)
{
int x1 = random.Next(width);
int y1 = random.Next(height);
int x2 = random.Next(width);
int y2 = random.Next(height);
canvas.DrawLine(x1, y1, x2, y2, paint);
}
// 在随机位置画背景点
for (int i = 0; i < 100; i++)
{
int x = random.Next(width);
int y = random.Next(height);
canvas.DrawCircle(x, y, 1, paint);
}
SKFont sKFont = new SKFont();
// 绘制文字
sKFont.Size = 21;
paint.IsAntialias = true;
//sKFont.Typeface = SKTypeface.FromFamilyName("Arial", SKFontStyleWeight.Bold, SKFontStyleWidth.Normal, SKFontStyleSlant.Upright);
sKFont.Typeface = SKTypeface.FromFile("msyh.ttc");
float textWidth = sKFont.MeasureText(code,paint);
SKColor[] fcolor = { SKColors.Black, SKColors.Red, SKColors.DarkBlue, SKColors.Green, SKColors.Orange, SKColors.Brown, SKColors.DarkCyan, SKColors.Purple,SKColors.DeepPink };
for (int i = 0; i < code.Length; i++)
{
int top = random.Next(5, 15);
int cindex = random.Next(7);
paint.Color = fcolor[cindex];
canvas.DrawText(code.Substring(i, 1), 5 + (i * 16), height / 2 + top, sKFont, paint);
}
}
}
using var image = SKImage.FromBitmap(bitmap);
using var data = image.Encode(SKEncodedImageFormat.Png, 100);
//using var stream = new MemoryStream();
data.SaveTo(ms);
//bitmap.Save(ms,SerializerCompression.GZip);
return ms;
}需要先把字体放在资源目录，记得字体文件要改为始终复制，本篇用到的是微软雅黑
然后打包到linux 放进docker即可成功显示
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