javascript - 绝对div不能在 Canvas 元素之上

Question

我正在使用 Leaflet，并且正在使用 FullCanvas plugin 的修改版本在 map 上画线。

http://jsfiddle.net/ruroor5v/

 $(document).ready(function() {
   var map = L.map('map').setView([0, 0], 13).setZoom(2);

   L.tileLayer('http://c.tile.openstreetmap.se/hydda/full/{z}/{x}/{y}.png').addTo(map);


   var markerLocations = [{
     "slat": 38.54,
     "slon": -100.19,
     "tlat": 52.37,
     "tlon": 4.89
   }, {
     "slat": 40.69,
     "slon": -74.04,
     "tlat": -33.93,
     "tlon": 18.42
   }, {
     "slat": 35.96,
     "slon": 138.70,
     "tlat": -22.59,
     "tlon": 138.60
   }, {
     "slat": 13.92,
     "slon": 103.04,
     "tlat": 13.92,
     "tlon": 104.04
   }, {
     "slat": 36.31,
     "slon": -117.07,
     "tlat": 43.83,
     "tlon": 142.38
   }];
   var layer = new L.SupplyChain();
   layer.setData(markerLocations);

   layer.addLayerTo(map);

   L.marker([38.54, -100.19], {
     icon: L.divIcon({
       // Specify a class name we can refer to in CSS.
       className: 'count-icon',
       // Define what HTML goes in each marker.
       html: '<div>I want on top!</div>',
       // Set a markers width and height.
       iconSize: [40, 40]
     })
   }).addTo(map);
 });

 if (typeof(L) !== 'undefined') {
   L.SupplyChain = L.Class.extend({
     options: this.options || {},
     initialize: function() {
       this._myCanvas = document.createElement('canvas');
       //  this._myCanvas.style.position = 'absolute';
       this._myCanvas.style.top = 0;
       this._myCanvas.style.left = 0;
       this._myContext = this._myCanvas.getContext('2d');
       this.options.filterPointsInBounds = false; // als je deze op true zet, verdwijnen supply chains uit beeld als het startpunt buiten beeld valt (handig voor tragere computers). 
     },
     setData: function(data) {
       var me = this;
       var bounds = new L.LatLngBounds([-90, -180], [90, 180]);
       this._myQuad = new QuadTree(this.boundsToQuery(bounds), false, 50, 10);
       data.forEach(function(d) {
         me._myQuad.insert({
           x: d.slat,
           y: d.slon,
           data: d
         });
         if (d.ty && d.tx) {
           me._myQuad.insert({
             x: d.tlat,
             y: d.tlon,
             data: d
           });
         }
       });
     },
     onAdd: function(map) {
       this._myMap = map;
       if (!map._panes.staticPane) {
         map._panes.staticPane = map._createPane('leaflet-tile-pane', map._container);
       }
       this._staticPane = map._panes.staticPane
       this._staticPane.appendChild(this._myCanvas);
       map.on('viewreset', this.canvasReset, this);
       map.on('move', this.canvasReset, this);
       map.on('resize', this.canvasReset, this);
       this.canvasReset();
     },
     addLayerTo: function(map) {
       map.addLayer(this);
       return this;
     },
     addTo: function(map) {
       this.addLayerTo(map);
       return this;
     },
     getCanvas: function() {
       return this._myCanvas;
     },

     getOptions: function() {
       return this.options;
     },
     canvasReset: function() {
       var size = this._myMap.getSize();
       this._myCanvas.width = size.x;
       this._myCanvas.height = size.y;
       this.drawCanvas();
     },
     onRemove: function(map) {
       map._container.removeChild(this._staticPane);
       map.off('viewreset', this.canvasReset, this);
       map.off('move', this.canvasReset, this);
       map.off('resize', this.canvasReset, this);
     },
     addData: function(d) {
       this._myQuad.insert({
         x: d.slat, //lon
         y: d.slon, //lat
         data: d
       });
       if (d.ty && d.tx) {
         this._myQuad.insert({
           x: d.tlat, //lon
           y: d.tlon, //lat
           data: d
         });
       }
       this.drawCanvas();
     },
     drawCanvas: function() {
       var canvas = this.getCanvas();
       var ctx = canvas.getContext('2d');
       var me = this;
       // clear canvas
       ctx.clearRect(0, 0, canvas.width, canvas.height);
       var bounds = this._myMap.getBounds();
       if (!this.options.filterPointsInBounds) bounds = new L.LatLngBounds([-90, -180], [90, 180]);
       var points = this._myQuad.retrieveInBounds(this.boundsToQuery(bounds));
       points.forEach(function(point) {
         var d = point.data;
         if (d.draw && !d.draw(d)) return; // allows dynamic filtering of curves
         var spoint = me._myMap.latLngToContainerPoint(new L.LatLng(d.slat, d.slon));
         //  me.drawPoint(spoint, "rgba(255,0,0, 0.5)");
         if (d.tlat && d.tlon) {
           var tpoint = me._myMap.latLngToContainerPoint(new L.LatLng(d.tlat, d.tlon));
           // me.drawPoint(tpoint, "rgba(0,255,0, 0.5)");
           me.drawCurve(point, spoint, tpoint, d.style ? d.style(d) : null);
         }
       });
     },
     redraw: function() {
       this.drawCanvas();
     },
     boundsToQuery: function(bounds) {
       return {
         x: bounds.getSouthWest().lat,
         y: bounds.getSouthWest().lng,
         width: bounds.getNorthEast().lat - bounds.getSouthWest().lat,
         height: bounds.getNorthEast().lng - bounds.getSouthWest().lng
       };
     },
     //drawPoint: function (point, colour) {
     //    var ctx = this.getCanvas().getContext("2d");
     //    ctx.beginPath();
     //    ctx.arc(point.x, point.y, 10, 0, 2 * Math.PI, true);
     //    ctx.fillStyle = colour;
     //    ctx.fill();
     //},
     drawCurve: function(point, startPoint, endPoint, style) {
       var ctx = this.getCanvas().getContext("2d");
       var arrowSize = 20;
       var defaultColour = (style && style.strokeStyle) ? style.strokeStyle : "rgb(0,0,255)";
       ctx.strokeStyle = defaultColour
       ctx.lineWidth = (style && style.lineWidth) ? style.lineWidth : 6;
       var x = (startPoint.x + endPoint.x) / 2;
       var y = (startPoint.y + endPoint.y) / 2;
       var le = (endPoint.y - endPoint.y) / (startPoint.x - endPoint.x);
       var angle = Math.atan(le);
       var sx = Math.pow((startPoint.x - endPoint.x), 2);
       var sy = Math.pow((endPoint.y - endPoint.y), 2);
       var d = Math.sqrt(sx + sy) / 2;

       var px = x - d * Math.sin(angle);
       var py;
       var sHigh = point.data.slat > 0;
       var sLow = point.data.slat < 0;
       var tHigh = point.data.tlat > 0;
       var tLow = point.data.tlat < 0;

       if ((sHigh && tHigh) || (sLow && tHigh)) {
         py = y + d * Math.cos(angle) * -1;
       } else if ((sLow && tLow) || (sHigh && tLow)) {
         py = y + d * Math.cos(angle);
       }

       ctx.moveTo(startPoint.x, startPoint.y);
       ctx.quadraticCurveTo(px, py, endPoint.x, endPoint.y);
       ctx.stroke();

       //var arrowDirection = Math.atan2(endPoint.y - py, endPoint.x - px) * 180 / Math.PI;

       //console.log(arrowDirection);

       //ctx.beginPath();
       //ctx.fillStyle = defaultColour;
       //ctx.moveTo(endPoint.x, endPoint.y);
       //ctx.lineTo(endPoint.x + arrowSize / 2, endPoint.y + arrowSize);
       //ctx.lineTo(endPoint.x - arrowSize / 2, endPoint.y + arrowSize);
       //ctx.lineTo(endPoint.x + arrowSize * Math.cos(arrowDirection + 90), endPoint.y + arrowSize * Math.sin(arrowDirection + 90));
       //ctx.closePath();
       //ctx.fill();
     },

   });

 }

 // voor de bovenstaande code heb ik de onderstaande code van Github gebruikt. Deze zorgt voor betere performance als er veel supply chains tegelijk in beeld zijn.   
 // Zie https://github.com/jsmarkus/ExamplesByMesh/tree/master/JavaScript/QuadTree voor meer uitleg. 

 /*
  The MIT License

  Copyright (c) 2011 Mike Chambers

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  */

 /*
  From https://github.com/jsmarkus/ExamplesByMesh/tree/master/JavaScript/QuadTree, slightly modified
  */


 /**
  * A QuadTree implementation in JavaScript, a 2d spatial subdivision algorithm.
  * @module QuadTree
  **/

 (function(window) {

   /****************** QuadTree ****************/

   /**
    * QuadTree data structure.
    * @class QuadTree
    * @constructor
    * @param {Object} An object representing the bounds of the top level of the QuadTree. The object
    * should contain the following properties : x, y, width, height
    * @param {Boolean} pointQuad Whether the QuadTree will contain points (true), or items with bounds
    * (width / height)(false). Default value is false.
    * @param {Number} maxDepth The maximum number of levels that the quadtree will create. Default is 4.
    * @param {Number} maxChildren The maximum number of children that a node can contain before it is split into sub-nodes.
    **/
   function QuadTree(bounds, pointQuad, maxDepth, maxChildren) {
     var node;
     if (pointQuad) {

       node = new Node(bounds, 0, maxDepth, maxChildren);
     } else {
       node = new BoundsNode(bounds, 0, maxDepth, maxChildren);
     }

     this.root = node;
   }

   /**
    * The root node of the QuadTree which covers the entire area being segmented.
    * @property root
    * @type Node
    **/
   QuadTree.prototype.root = null;


   /**
    * Inserts an item into the QuadTree.
    * @method insert
    * @param {Object|Array} item The item or Array of items to be inserted into the QuadTree. The item should expose x, y
    * properties that represents its position in 2D space.
    **/
   QuadTree.prototype.insert = function(item) {
     if (item instanceof Array) {
       var len = item.length;

       for (var i = 0; i < len; i++) {
         this.root.insert(item[i]);
       }
     } else {
       this.root.insert(item);
     }
   };

   /**
    * Clears all nodes and children from the QuadTree
    * @method clear
    **/
   QuadTree.prototype.clear = function() {
     this.root.clear();
   };

   /**
    * Retrieves all items / points in the same node as the specified item / point. If the specified item
    * overlaps the bounds of a node, then all children in both nodes will be returned.
    * @method retrieve
    * @param {Object} item An object representing a 2D coordinate point (with x, y properties), or a shape
    * with dimensions (x, y, width, height) properties.
    **/
   QuadTree.prototype.retrieve = function(item) {
     //get a copy of the array of items
     var out = this.root.retrieve(item).slice(0);
     //return QuadTree._filterResults(out, {x:item.x, y:item.y, width:0, height:0});
     return out;
   };

   QuadTree.prototype.retrieveInBounds = function(bounds) {
     var treeResult = this.root.retrieveInBounds(bounds);
     return QuadTree._filterResults(treeResult, bounds);
   };

   QuadTree._filterResults = function(treeResult, bounds) {
     var filteredResult = [];

     if (this.root instanceof BoundsNode) {
       for (var i = 0; i < treeResult.length; i++) {
         var node = treeResult[i];
         if (QuadTree._isBoundOverlappingBound(node, bounds)) {
           filteredResult.push(node);
         }
       }
     } else {
       treeResult.forEach(function(node) {
         if (QuadTree._isPointInsideBounds(node, bounds)) {
           filteredResult.push(node);
         }
       });
     }

     return filteredResult;
   };

   QuadTree._isPointInsideBounds = function(point, bounds) {
     return (
       (point.x >= bounds.x) &&
       (point.x <= bounds.x + bounds.width) &&
       (point.y >= bounds.y) &&
       (point.y <= bounds.y + bounds.height)
     );
   };


   QuadTree._isBoundOverlappingBound = function(b1, b2) {
     return !(
       b1.x > (b2.x + b2.width) ||
       b2.x > (b1.x + b1.width) ||
       b1.y > (b2.y + b2.height) ||
       b2.y > (b1.y + b1.height)
     );
   };

   /************** Node ********************/


   function Node(bounds, depth, maxDepth, maxChildren) {
     this._bounds = bounds;
     this.children = [];
     this.nodes = [];

     if (maxChildren) {
       this._maxChildren = maxChildren;

     }

     if (maxDepth) {
       this._maxDepth = maxDepth;
     }

     if (depth) {
       this._depth = depth;
     }
   };

   //subnodes
   Node.prototype.nodes = null;
   Node.prototype._classConstructor = Node;

   //children contained directly in the node
   Node.prototype.children = null;
   Node.prototype._bounds = null;

   //read only
   Node.prototype._depth = 0;

   Node.prototype._maxChildren = 4;
   Node.prototype._maxDepth = 4;

   Node.TOP_LEFT = 0;
   Node.TOP_RIGHT = 1;
   Node.BOTTOM_LEFT = 2;
   Node.BOTTOM_RIGHT = 3;


   Node.prototype.insert = function(item) {
     if (this.nodes.length) {
       var index = this._findIndex(item);

       this.nodes[index].insert(item);

       return;
     }

     this.children.push(item);

     var len = this.children.length;
     if (!(this._depth >= this._maxDepth) &&
       len > this._maxChildren) {
       this.subdivide();

       for (var i = 0; i < len; i++) {
         this.insert(this.children[i]);
       }

       this.children.length = 0;
     }
   };

   Node.prototype.retrieve = function(item) {
     if (this.nodes.length) {
       var index = this._findIndex(item);

       return this.nodes[index].retrieve(item);
     }

     return this.children;
   };

   Node.prototype.retrieveInBounds = function(bounds) {
     var result = [];

     if (this.collidesWith(bounds)) {
       result = result.concat(this._stuckChildren);

       if (this.children.length) {
         result = result.concat(this.children);
       } else {
         if (this.nodes.length) {
           for (var i = 0; i < this.nodes.length; i++) {
             result = result.concat(this.nodes[i].retrieveInBounds(bounds));
           }
         }
       }
     }

     return result;
   };


   Node.prototype.collidesWith = function(bounds) {
     var b1 = this._bounds;
     var b2 = bounds;

     return !(
       b1.x > (b2.x + b2.width) ||
       b2.x > (b1.x + b1.width) ||
       b1.y > (b2.y + b2.height) ||
       b2.y > (b1.y + b1.height)
     );
   };

   Node.prototype._findIndex = function(item) {
     var b = this._bounds;
     var left = (item.x > b.x + b.width / 2) ? false : true;
     var top = (item.y > b.y + b.height / 2) ? false : true;

     //top left
     var index = Node.TOP_LEFT;
     if (left) {
       //left side
       if (!top) {
         //bottom left
         index = Node.BOTTOM_LEFT;
       }
     } else {
       //right side
       if (top) {
         //top right
         index = Node.TOP_RIGHT;
       } else {
         //bottom right
         index = Node.BOTTOM_RIGHT;
       }
     }

     return index;
   };


   Node.prototype.subdivide = function() {
     var depth = this._depth + 1;

     var bx = this._bounds.x;
     var by = this._bounds.y;

     //floor the values
     var b_w_h = (this._bounds.width / 2) | 0;
     var b_h_h = (this._bounds.height / 2) | 0;
     var bx_b_w_h = bx + b_w_h;
     var by_b_h_h = by + b_h_h;

     //top left
     this.nodes[Node.TOP_LEFT] = new this._classConstructor({
         x: bx,
         y: by,
         width: b_w_h,
         height: b_h_h
       },
       depth, this._maxDepth, this._maxChildren);

     //top right
     this.nodes[Node.TOP_RIGHT] = new this._classConstructor({
         x: bx_b_w_h,
         y: by,
         width: b_w_h,
         height: b_h_h
       },
       depth, this._maxDepth, this._maxChildren);

     //bottom left
     this.nodes[Node.BOTTOM_LEFT] = new this._classConstructor({
         x: bx,
         y: by_b_h_h,
         width: b_w_h,
         height: b_h_h
       },
       depth, this._maxDepth, this._maxChildren);


     //bottom right
     this.nodes[Node.BOTTOM_RIGHT] = new this._classConstructor({
         x: bx_b_w_h,
         y: by_b_h_h,
         width: b_w_h,
         height: b_h_h
       },
       depth, this._maxDepth, this._maxChildren);
   };

   Node.prototype.clear = function() {
     this.children.length = 0;

     var len = this.nodes.length;
     for (var i = 0; i < len; i++) {
       this.nodes[i].clear();
     }

     this.nodes.length = 0;
   };


   /******************** BoundsQuadTree ****************/

   function BoundsNode(bounds, depth, maxChildren, maxDepth) {
     Node.call(this, bounds, depth, maxChildren, maxDepth);
     this._stuckChildren = [];
   }

   BoundsNode.prototype = new Node();
   BoundsNode.prototype._classConstructor = BoundsNode;
   BoundsNode.prototype._stuckChildren = null;

   //we use this to collect and conctenate items being retrieved. This way
   //we dont have to continuously create new Array instances.
   //Note, when returned from QuadTree.retrieve, we then copy the array
   BoundsNode.prototype._out = [];

   BoundsNode.prototype.insert = function(item) {
     if (this.nodes.length) {
       var index = this._findIndex(item);
       var node = this.nodes[index];

       //todo: make _bounds bounds
       if (item.x >= node._bounds.x &&
         item.x + item.width <= node._bounds.x + node._bounds.width &&
         item.y >= node._bounds.y &&
         item.y + item.height <= node._bounds.y + node._bounds.height) {
         this.nodes[index].insert(item);
       } else {
         this._stuckChildren.push(item);
       }

       return;
     }

     this.children.push(item);

     var len = this.children.length;

     if (this._depth < this._maxDepth &&
       len > this._maxChildren) {
       this.subdivide();

       for (var i = 0; i < len; i++) {
         this.insert(this.children[i]);
       }

       this.children.length = 0;
     }
   };

   BoundsNode.prototype.getChildren = function() {
     return this.children.concat(this._stuckChildren);
   };

   BoundsNode.prototype.retrieve = function(item) {
     var out = this._out;
     out.length = 0;
     if (this.nodes.length) {
       var index = this._findIndex(item);

       out.push.apply(out, this.nodes[index].retrieve(item));
     }

     out.push.apply(out, this._stuckChildren);
     out.push.apply(out, this.children);

     return out;
   };

   BoundsNode.prototype.clear = function() {

     this._stuckChildren.length = 0;

     //array
     this.children.length = 0;

     var len = this.nodes.length;

     if (!len) {
       return;
     }

     for (var i = 0; i < len; i++) {
       this.nodes[i].clear();
     }

     //array
     this.nodes.length = 0;

     //we could call the super clear function but for now, im just going to inline it
     //call the hidden super.clear, and make sure its called with this = this instance
     //Object.getPrototypeOf(BoundsNode.prototype).clear.call(this);
   };

   //BoundsNode.prototype.getChildCount

   window.QuadTree = QuadTree;

   /*
    //http://ejohn.org/blog/objectgetprototypeof/
    if ( typeof Object.getPrototypeOf !== "function" ) {
    if ( typeof "test".__proto__ === "object" ) {
    Object.getPrototypeOf = function(object){
    return object.__proto__;
    };
    } else {
    Object.getPrototypeOf = function(object){
    // May break if the constructor has been tampered with
    return object.constructor.prototype;
    };
    }
    }
    */

 }(this));

.count-icon {
  background-color: #ff0000;
  width: 250px;
  height: 250px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js"></script>
<link href="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.css" rel="stylesheet" />


<div id="map" style="height: 800px; width:1000px"></div>

在Firebug中检查元素时，红色方 block 有绝对定位，而canvas元素没有定位。 canvas 元素具有以下样式:

element {
top: 0px;
left: 0px;
}

.leaflet-container {
font: 12px/1.5 "Helvetica Neue",Arial,Helvetica,sans-serif;
}

.leaflet-container {
cursor: grab;
}

红色方 block 的样式是这样的:

element {
margin-left: -20px;
margin-top: -20px;
width: 40px;
height: 40px;
transform: translate(215px, 281px);
z-index: 281;
}
.count-icon {
background-color: #F00;
width: 250px;
height: 250px;
}
.leaflet-clickable {
cursor: pointer;
}
.leaflet-marker-icon, .leaflet-marker-shadow {
display: block;
}
.leaflet-tile, .leaflet-marker-icon, .leaflet-marker-shadow {
-moz-user-select: none;
}
.leaflet-map-pane, .leaflet-tile, .leaflet-marker-icon, .leaflet-marker-shadow, .leaflet-tile-pane, .leaflet-tile-container, .leaflet-overlay-pane, .leaflet-shadow-pane, .leaflet-marker-pane, .leaflet-popup-pane, .leaflet-overlay-pane svg, .leaflet-zoom-box, .leaflet-image-layer, .leaflet-layer {
position: absolute;
left: 0px;
top: 0px;
}
.leaflet-container {
font: 12px/1.5 "Helvetica Neue",Arial,Helvetica,sans-serif;

我怎样才能得到蓝线上方的红色方 block ？

Answer 1

.leaflet-map-pane 使用 transform: translate3d(x,y,z) 定位。由于 translate3d 现在控制 z 轴，因此 z-index 被忽略。 (如果您在检查器/开发工具中删除/切换 .leaflet-map-pane 的 translate3d 属性，您会看到它起作用。)

我看不到代码中设置此 translate3d 样式的位置(大概是 leaflet.js)，但您可以将其替换为绝对定位。

更新:这里有几个屏幕截图显示了我所指的元素。

屏幕截图 1:leaflet-map-pane 应用了 translate3d。

屏幕截图 2:检查器中禁用了 translate3d 样式。