基于leaflet.js实现修改地图主题样式的流程分析

/*
 * L.TileLayer.Colorizr is a regular tilelayer with mapped colors.
 */
(function () {
 // L.TileLayer.Colorizr = 
 var Colorizr = L.TileLayer.extend({
  initialize: function (url, options) {
   options = L.extend({}, L.TileLayer.prototype.options, {
    colorize: function (pixel) {
     return pixel;
    },
    crossOrigin: 'Anonymous'
   }, options);
   L.TileLayer.prototype.initialize.call(this, url, options);
   L.setOptions(this, options);
   this.setColorizr(this.options.colorize);
   this.on('tileload', function (e) {
    this._colorize(e.tile);
   });
  },
  setColorizr: function (colorizrFactory) {
   if (!colorizrFactory || typeof colorizrFactory !== 'function') {
    throw 'The colorize option should be a function and return an object with at least one of "r", "g", "b", or "a" properties. Got:' +
    typeof colorizrFactory;
   } else {
    this.options.colorize = colorizrFactory;
   }
   this.redraw(false);
  },
  _createTile: function () {
   var tile = L.TileLayer.prototype._createTile.call(this);
   tile.crossOrigin = "Anonymous";
   return tile;
  },
  _colorize: function (img) {
   if (img.getAttribute('data-colorized')) {
    img.hidden = false;
    return;
   }else {
    img.hidden = true;
   }
   var _img = img;
   var img = new Image();
   img.crossOrigin = 'Anonymous';
   img.src = _img.src;
   var _this = this;
   img.onload = function () {
    var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;
    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0);
    var imgd = ctx.getImageData(0, 0, canvas.width, canvas.height);
    var pix = imgd.data;
    for (var i = 0, n = pix.length; i < n; i += 4) {
     var pixel = _this.options.colorize({r: pix[i], g: pix[i + 1], b: pix[i + 2], a: pix[i + 3]});
     if (!!!pixel || pixel !== Object(pixel) || Object.prototype.toString.call(pixel) === '[object Array]') {
      if (i === 0) {
       throw 'The colorize option should return an object with at least one of "r", "g", "b", or "a" properties.';
      }
     } else {
      if (pixel.hasOwnProperty('r') && typeof pixel.r === 'number') {
       pix[i] = pixel.r;
      }
      if (pixel.hasOwnProperty('g')) {
       pix[i + 1] = pixel.g;
      }
      if (pixel.hasOwnProperty('b')) {
       pix[i + 2] = pixel.b;
      }
      if (pixel.hasOwnProperty('a')) {
       pix[i + 3] = pixel.a;
      }
     }
    }
    ctx.putImageData(imgd, 0, 0);
    _img.setAttribute('data-colorized', true);
    _img.src = canvas.toDataURL();
   };
  }
 });
 (function (factory, window) {
  // define an AMD module that relies on 'leaflet'
  if (typeof define === 'function' && define.amd) {
   define(['leaflet'], factory);
   // define a Common JS module that relies on 'leaflet'
  } else if (typeof exports === 'object') {
   module.exports = factory(require('leaflet'));
  }
  // attach your plugin to the global 'L' variable
  if (typeof window !== 'undefined' && window.L) {
   window.L.tileLayer.colorizr = factory(L);
  }
 }(function (L) {
  return function (url, options) {
   return new Colorizr(url, options);
  };
 }, window));
})()

 var map = L.map("map", {
  center: [34.694, 113.587],
  renderer: L.svg(),
  zoom: 16,
  zoomControl: false, // + -号放大缩小
  attributionControl: false // 右下角leaflet.js图标
 });
 // http://192.168.0.105:9090/img/{z}/{x}/{y}.png // 这个是瓦片地图的地址
 L.tileLayer.colorizr("http://localhost:9090/img/{z}/{x}/{y}.png", {
  maxZoom: 18,
  minZoom: 3,
  colorize: function (pixel) {
   // 这个方法用来调整所有的图片上的rgb值，pixel是图片原有的rgb值
   pixel.r += 13;
   pixel.g += 17;
   pixel.b += 90;
   return pixel;
  }
 }).addTo(map);

.leaflet-zoom-animated img {
   -webkit-filter: invert(50%) grayscale(0) saturate(0.5) brightness(1.6) opacity(1) hue-rotate(334deg) sepia(10%) !important;
   -ms-filter: invert(1) grayscale(0) saturate(0.5) brightness(1.6) opacity(1) hue-rotate(334deg) sepia(10%) !important;
   -moz-filter: invert(1) grayscale(0) saturate(0.5) brightness(1.6) opacity(1) hue-rotate(334deg) sepia(10%) !important;
   filter: invert(1) grayscale(0) saturate(0.5) brightness(1.6) opacity(1) hue-rotate(334deg) sepia(1%) !important;
  }