javascript - 强制有向图和本地存储

Question

我试图在本地存储中拖放后存储节点位置，但是当我重新加载页面时，链接是我保存它们的位置，节点也是如此，但链接和节点没有链接，因此节点只是从他们的初始位置。

这是我的代码，我使用的是 Angular。

angular.module('core').controller('HomeController', ['$scope', 
function($scope) {
    $scope.graph = {
        width : 500,
        height : 400,
        color : d3.scale.category20(),
        force : '',
        drag : '',
        dragstart : function(d) {
            d.x = d3.event.x;
            d.y = d3.event.y;
        },
        dragend : function(d) {
            var graphTmp = { "nodes" : $scope.graph.node.data(), "links" : $scope.graph.link.data()};
            localStorage.setItem('graph',JSON.stringify(graphTmp));
        },
        link : [],
        node : [],
        links : [],
        nodes : []
    };
    $scope.svg = d3.select("body").append("svg")
            .attr("width", $scope.graph.width)
            .attr("height", $scope.graph.height);
    $scope.savedGraph = {};

    $scope.draw = function(){
        $scope.graph.force = d3.layout.force()
                .charge(-120)
                .linkDistance(30)
                .size([$scope.graph.width, $scope.graph.height]);

        $scope.graph.force
              .nodes($scope.graph.nodes)
              .links($scope.graph.links)
              .start();

        $scope.graph.link = $scope.svg.selectAll(".link")
            .data($scope.graph.links)
            .enter().append("line")
            .attr("class", "link")
            .style({'stroke' : 'gray', 'stroke-width' : '1px'});

        $scope.graph.drag = $scope.graph.force.drag()
            .on("dragstart", $scope.graph.dragstart)
            .on("dragend", $scope.graph.dragend);

        $scope.graph.node = $scope.svg.selectAll(".node")
            .data($scope.graph.nodes)
            .enter().append("circle")
            .attr("class", "node")
            .attr("r", 5)
            .style("fill", function(d) { return $scope.graph.color(d.group); })
            .call($scope.graph.drag);

        $scope.graph.node
            .append("title")
            .text(function(d) { return d.name; });

        $scope.graph.force.on("tick", function() {
            $scope.graph.link
                .attr("x1", function(d) { return d.source.x; })
                .attr("y1", function(d) { return d.source.y; })
                .attr("x2", function(d) { return d.target.x; })
                .attr("y2", function(d) { return d.target.y; });

            $scope.graph.node
                .attr("cx", function(d) { return d.x; })
                .attr("cy", function(d) { return d.y; });
        });
    };

    if(localStorage.getItem('graph') === null){

        $scope.graph.nodes = [
            {"name":"Myriel","group":1},
            {"name":"Napoleon","group":1},
            {"name":"Mlle.Baptistine","group":1},
            {"name":"Mme.Magloire","group":1},
            {"name":"CountessdeLo","group":1},
            {"name":"Geborand","group":1},
            {"name":"Champtercier","group":1},
            {"name":"Cravatte","group":1},
            {"name":"Count","group":1}
        ];

        $scope.graph.links = [
            {"source":1,"target":0,"value":1},
            {"source":2,"target":0,"value":8},
            {"source":3,"target":0,"value":10},
            {"source":3,"target":2,"value":6},
            {"source":4,"target":0,"value":1}
        ];

        $scope.draw();
    }
    else {
        var graphTmp = $.parseJSON(localStorage.getItem('graph'));
        $scope.graph.links = graphTmp.links;
        $scope.graph.nodes = graphTmp.nodes;
        $scope.draw();

    }

有人知道为什么吗？我认为这是因为节点和链接无法仅使用 node.data() 和 link.data() 数据链接在一起。我可以存储更多数据吗？

谢谢!

Answer 1

问题是，最初当您加载链接时(本地存储中没有数据)，它具有以下结构:

 $scope.graph.links = [{
            "source": 1,
            "target": 0,
            "value": 1
        }, {
            "source": 2,
            "target": 0,
            "value": 8
        }, {
            "source": 3,
            "target": 0,
            "value": 10
        }, {
            "source": 3,
            "target": 2,
            "value": 6
        }, {
            "source": 4,
            "target": 0,
            "value": 1
        }];

现在强制布局将用节点中的源对象替换源索引。

拖动时，您会保存节点和链接(链接对象将保存源和目标的节点对象)。

现在，当您从本地存储加载并解析链接时，链接源/目标将具有与节点对象不同的对象(因为它是深度克隆的)。

因此，节点上的拖动更改将不会反射(reflect)在链接源/目标对象上。因此链接会分离。

问题的解决方案是始终将链接的索引形式存储在本地存储中。我在这里通过保留另一个对象 initLinks 来做到这一点

$scope.graph.nodes = [{
    "name": "Myriel",
    "group": 1
}, {
    "name": "Napoleon",
    "group": 1
}, {
    "name": "Mlle.Baptistine",
    "group": 1
}, {
    "name": "Mme.Magloire",
    "group": 1
}, {
    "name": "CountessdeLo",
    "group": 1
}, {
    "name": "Geborand",
    "group": 1
}, {
    "name": "Champtercier",
    "group": 1
}, {
    "name": "Cravatte",
    "group": 1
}, {
    "name": "Count",
    "group": 1
}];

$scope.graph.links = [{
    "source": 1,
    "target": 0,
    "value": 1
}, {
    "source": 2,
    "target": 0,
    "value": 8
}, {
    "source": 3,
    "target": 0,
    "value": 10
}, {
    "source": 3,
    "target": 2,
    "value": 6
}, {
    "source": 4,
    "target": 0,
    "value": 1
}];
$scope.graph.initLinks = angular.copy($scope.graph.links);

保存到本地存储时我这样做

    var graphTmp = {
        "nodes": $scope.graph.nodes,
        "links": $scope.graph.initLinks
    };

    localStorage.setItem('graph', JSON.stringify(graphTmp));

从本地存储加载时我这样做

var graphTmp = JSON.parse(localStorage.getItem('graph'));
$scope.graph.links =  graphTmp.links;
$scope.graph.initLinks = angular.copy(graphTmp.links);
$scope.graph.nodes = graphTmp.nodes;
$scope.draw();

工作代码here

希望这有帮助!