{  "headers": {    
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3",     
    "Accept-Encoding": "gzip, deflate, br",     
    "Accept-Language": "zh-CN,zh;q=0.9,en;q=0.8",     
    "Host": "httpbin.org",     
    "Sec-Fetch-Mode": "navigate",     
    "Sec-Fetch-Site": "none",     
    "Sec-Fetch-User": "?1",     
    "Upgrade-Insecure-Requests": "1",     
    "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36"
  }}

function getCanvasFingerprint () {    
    var canvas = document.createElement('canvas');    
    var context = canvas.getContext("2d");    
    context.font = "18pt Arial";    
    context.textBaseline = "top";    
    context.fillText("Hello, user.", 2, 2);    
    return canvas.toDataURL("image/jpeg");
}
getCanvasFingerprint()

gl = getWebglCanvas()    
if (!gl) { return null }    
var result = []    
var vShaderTemplate = 'attribute vec2 attrVertex;varying vec2 varyinTexCoordinate;uniform vec2 uniformOffset;void main(){varyinTexCoordinate=attrVertex+uniformOffset;gl_Position=vec4(attrVertex,0,1);}'
var fShaderTemplate = 'precision mediump float;varying vec2 varyinTexCoordinate;void main() {gl_FragColor=vec4(varyinTexCoordinate,0,1);}'
var vertexPosBuffer = gl.createBuffer()    
gl.bindBuffer(gl.ARRAY_BUFFER, vertexPosBuffer)    
var vertices = new Float32Array([-0.2, -0.9, 0, 0.4, -0.26, 0, 0, 0.732134444, 0])
// 创建并初始化了Buffer对象的数据存储区。
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW) 
vertexPosBuffer.itemSize = 3
vertexPosBuffer.numItems = 3
// 创建和初始化一个WebGLProgram对象。
var program = gl.createProgram()
// 创建着色器对象
var vshader = gl.createShader(gl.VERTEX_SHADER)
// 下两行配置着色器 
gl.shaderSource(vshader, vShaderTemplate)  // 设置着色器代码 
gl.compileShader(vshader) // 编译一个着色器，以便被WebGLProgram对象所使用
var fshader = gl.createShader(gl.FRAGMENT_SHADER)   
gl.shaderSource(fshader, fShaderTemplate)    
gl.compileShader(fshader)    
// 添加预先定义好的顶点着色器和片段着色器 
gl.attachShader(program, vshader)
gl.attachShader(program, fshader) 
// 链接WebGLProgram对象 
gl.linkProgram(program)
// 定义好的WebGLProgram对象添加到当前的渲染状态 
gl.useProgram(program)    
program.vertexPosAttrib = gl.getAttribLocation(program, 'attrVertex')    
program.offsetUniform = gl.getUniformLocation(program, 'uniformOffset')                           gl.enableVertexAttribArray(program.vertexPosArray)    
gl.vertexAttribPointer(program.vertexPosAttrib, vertexPosBuffer.itemSize, gl.FLOAT, !1, 0, 0)    
gl.uniform2f(program.offsetUniform, 1, 1)
// 从向量数组中绘制图元 
gl.drawArrays(gl.TRIANGLE_STRIP, 0, vertexPosBuffer.numItems)    
try {        
    result.push(gl.canvas.toDataURL())    
} catch (e) {        
    /* .toDataURL may be absent or broken (blocked by extension) */
}

const toDataURL = HTMLCanvasElement.prototype.toDataURL;
HTMLCanvasElement.prototype.manipulate = function() {
  const {width, height} = this;
  // 拿到在进行toDataURL或者toBlob前的canvas所生成的CanvasRenderingContext2D
  const context = this.getContext('2d'); 
  const shift = {
    'r': Math.floor(Math.random() * 10) - 5,
    'g': Math.floor(Math.random() * 10) - 5,
    'b': Math.floor(Math.random() * 10) - 5
  };
  const matt = context.getImageData(0, 0, width, height);
  // 对getImageData生成的imageData（像素源数据）中的每一个像素的r、g、b部分的值进行进行随机改变从而生成唯一的图像。
  for (let i = 0; i < height; i += Math.max(1, parseInt(height / 10))) {
    for (let j = 0; j < width; j += Math.max(1, parseInt(width / 10))) {
      const n = ((i * (width * 4)) + (j * 4));
      matt.data[n + 0] = matt.data[n + 0] + shift.r; // 加上随机扰动
      matt.data[n + 1] = matt.data[n + 1] + shift.g;
      matt.data[n + 2] = matt.data[n + 2] + shift.b;
    }
  }
  context.putImageData(matt, 0, 0); // 重新放回去
// 修改prototype.toBlob
Object.defineProperty(HTMLCanvasElement.prototype, 'toBlob', {
  value: function() {
    if (script.dataset.active === 'true') {
      try {
        this.manipulate(); // 在每次toBlob前，先混淆下ImageData
      }
      catch(e) {
        console.warn('manipulation failed', e);
      }
    }
    return toBlob.apply(this, arguments);
  }
});
// 修改prototype. toDataURL
Object.defineProperty(HTMLCanvasElement.prototype, 'toDataURL', {
  value: function() {
    if (script.dataset.active === 'true') {
      try {
        this.manipulate(); // 在每次toDataURL前，先混淆下ImageData
      }
      catch(e) {
        console.warn('manipulation failed', e);
      }
    }
    return toDataURL.apply(this, arguments);
  }
});