如何在页面刷新mxgraph上保留绘制的框和路径

Question

i want to retain drawn boxes and path once page is refreshed.我想在页面刷新后保留绘制的boxes和路径。

i'm using mxgraph https://jgraph.github.io/mxgraph/docs/manual.html我正在使用mxgraph https://jgraph.github.io/mxgraph/docs/manual.html

Question: once the drawing is done, if i do page refresh it should retain the same drawing by storing drawing data into localStorage.问题：绘图完成后，如果我刷新页面，它应该通过将绘图数据存储到 localStorage 来保留相同的绘图。

NOTE: i want to get json object of drawn canvas , and re-construct it back from that object on page refresh.注意：我想获取绘制canvas json object ，并在页面刷新时从该object重新构造它。

Below video shows how to draw: https://drive.google.com/file/d/1McTMz3e8I_quOcLGt2CtaQhqif3R31qs/view下面的视频显示了如何绘制： https : //drive.google.com/file/d/1McTMz3e8I_quOcLGt2CtaQhqif3R31qs/view

 https://jgraph.github.io/mxgraph/javascript/examples/editors/images/

 <!-- Copyright (c) 2006-2013, JGraph Ltd Dynamic toolbar example for mxGraph. This example demonstrates changing the state of the toolbar at runtime. --> <html> <head> <title>Toolbar example for mxGraph</title> <!-- Sets the basepath for the library if not in same directory --> <script type="text/javascript"> mxBasePath = 'https://jgraph.github.io/mxgraph/javascript/src'; </script> <!-- Loads and initializes the library --> <script type="text/javascript" src="https://jgraph.github.io/mxgraph/javascript/src/js/mxClient.js"></script> <!-- Example code --> <script type="text/javascript"> // Program starts here. Creates a sample graph in the // DOM node with the specified ID. This function is invoked // from the onLoad event handler of the document (see below). function main() { // Checks if browser is supported if (!mxClient.isBrowserSupported()) { // Displays an error message if the browser is // not supported. mxUtils.error('Browser is not supported!', 200, false); } else { // Defines an icon for creating new connections in the connection handler. // This will automatically disable the highlighting of the source vertex. mxConnectionHandler.prototype.connectImage = new mxImage('images/connector.gif', 16, 16); // Creates the div for the toolbar var tbContainer = document.createElement('div'); tbContainer.style.position = 'absolute'; tbContainer.style.overflow = 'hidden'; tbContainer.style.padding = '2px'; tbContainer.style.left = '0px'; tbContainer.style.top = '0px'; tbContainer.style.width = '24px'; tbContainer.style.bottom = '0px'; document.body.appendChild(tbContainer); // Creates new toolbar without event processing var toolbar = new mxToolbar(tbContainer); toolbar.enabled = false // Creates the div for the graph var container = document.createElement('div'); container.style.position = 'absolute'; container.style.overflow = 'hidden'; container.style.left = '24px'; container.style.top = '0px'; container.style.right = '0px'; container.style.bottom = '0px'; container.style.background = 'url("editors/images/grid.gif")'; document.body.appendChild(container); // Workaround for Internet Explorer ignoring certain styles if (mxClient.IS_QUIRKS) { document.body.style.overflow = 'hidden'; new mxDivResizer(tbContainer); new mxDivResizer(container); } // Creates the model and the graph inside the container // using the fastest rendering available on the browser var model = new mxGraphModel(); var graph = new mxGraph(container, model); // Enables new connections in the graph graph.setConnectable(true); graph.setMultigraph(false); // Stops editing on enter or escape keypress var keyHandler = new mxKeyHandler(graph); var rubberband = new mxRubberband(graph); var addVertex = function(icon, w, h, style) { var vertex = new mxCell(null, new mxGeometry(0, 0, w, h), style); vertex.setVertex(true); var img = addToolbarItem(graph, toolbar, vertex, icon); img.enabled = true; graph.getSelectionModel().addListener(mxEvent.CHANGE, function() { var tmp = graph.isSelectionEmpty(); mxUtils.setOpacity(img, (tmp) ? 100 : 20); img.enabled = tmp; }); }; addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/rectangle.gif', 100, 40, ''); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/rounded.gif', 100, 40, 'shape=rounded'); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/ellipse.gif', 40, 40, 'shape=ellipse'); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/rhombus.gif', 40, 40, 'shape=rhombus'); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/triangle.gif', 40, 40, 'shape=triangle'); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/cylinder.gif', 40, 40, 'shape=cylinder'); addVertex('https://jgraph.github.io/mxgraph/javascript/examples/editors/images/actor.gif', 30, 40, 'shape=actor'); } } function addToolbarItem(graph, toolbar, prototype, image) { // Function that is executed when the image is dropped on // the graph. The cell argument points to the cell under // the mousepointer if there is one. var funct = function(graph, evt, cell, x, y) { graph.stopEditing(false); var vertex = graph.getModel().cloneCell(prototype); vertex.geometry.x = x; vertex.geometry.y = y; graph.addCell(vertex); graph.setSelectionCell(vertex); } // Creates the image which is used as the drag icon (preview) var img = toolbar.addMode(null, image, function(evt, cell) { var pt = this.graph.getPointForEvent(evt); funct(graph, evt, cell, pt.x, pt.y); }); // Disables dragging if element is disabled. This is a workaround // for wrong event order in IE. Following is a dummy listener that // is invoked as the last listener in IE. mxEvent.addListener(img, 'mousedown', function(evt) { // do nothing }); // This listener is always called first before any other listener // in all browsers. mxEvent.addListener(img, 'mousedown', function(evt) { if (img.enabled == false) { mxEvent.consume(evt); } }); mxUtils.makeDraggable(img, graph, funct); return img; } </script> </head> <!-- Calls the main function after the page has loaded. Container is dynamically created. --> <body onload="main();" > </body> </html>

Answer 1

This uses the XML encoding of mxgraph.这使用了 mxgraph 的 XML 编码。 You see this code in one of the examples of mxGraph.您可以在 mxGraph 的示例之一中看到此代码。 While it is not json, it is very easy to turn into json, and can be edited or saved as you wish.虽然不是json，但是转json很容易，可以随意编辑或保存。 Now it it stored in localStorage as you asked.现在它按照您的要求存储在 localStorage 中。

Add the following lines at the end of your main function (after the last call to addVertex):在主函数的末尾添加以下几行（在最后一次调用 addVertex 之后）：

// read state on load 
if(window.localStorage.graphState){
    var doc = mxUtils.parseXml(window.localStorage.graphState);
    var dec = new mxCodec(doc);
    dec.decode(doc.documentElement, graph.getModel());
}

// save state on change
graph.getModel().addListener('change',function(){
    var codec = new mxCodec();
    window.localStorage.graphState = codec.encode(
            graph.getModel()
        ).outerHTML;
});

Update using JSON使用 JSON 更新

Update 2: Switched to my own custom html2json and json2html implementation to make the answer fully self-contained更新 2：切换到我自己的自定义 html2json 和 json2html 实现，使答案完全独立

If you do need a proper JSON object, you can convert from xml to json and back.如果您确实需要一个合适的 JSON 对象，您可以将 xml 转换为 json 并返回。 Below you can see I stringify and parse the json object, this is only needed to save it in localStorage though.在下面你可以看到我对 json 对象进行了字符串化和解析，这只是需要将它保存在 localStorage 中。

First add these two functions to convert from html/xml to json and from json back to html/xml:首先添加这两个函数，实现从html/xml到json和从json再到html/xml的转换：

function html2json(html){
    if(html.nodeType==3){
        return {
            "tagName":"#text",
            "content":html.textContent
        }
    }
    var element = {
        "tagName":html.tagName
    };

    if(html.getAttributeNames().length>0){
        element.attributes = html.getAttributeNames().reduce(
            function(acc,at){acc[at]=html.getAttribute(at); return acc;},
            {}
        );
    }

    if(html.childNodes.length>0){
        element.children = Array.from(html.childNodes)
            .filter(
                function(el){
                    return el.nodeType!=3
                    ||el.textContent.trim().length>0
                })
            .map(function(el){return html2json(el);});
    }
    return element;
}

function json2html(json){
    var xmlDoc = document.implementation.createDocument(null, json.tagName);

    var addAttributes = function(jsonNode, node){
        if(jsonNode.attributes){
            Object.keys(jsonNode.attributes).map(
                function(name){
                    node.setAttribute(name,jsonNode.attributes[name]);
                }
            );
        }
    }

    var addChildren = function(jsonNode,node){
        if(jsonNode.children){
            jsonNode.children.map(
                function(jsonChildNode){
                    json2htmlNode(jsonChildNode,node);
                }
            );
        }
    }

    var json2htmlNode = function(jsonNode,parent){
        if(jsonNode.tagName=="#text"){
            return xmlDoc.createTextNode(jsonNode.content);
        }

        var node = xmlDoc.createElement(jsonNode.tagName);

        addAttributes(jsonNode,node);
        addChildren(jsonNode,node);

        parent.appendChild(node);
    }

    addAttributes(json,xmlDoc.firstElementChild);
    addChildren(json,xmlDoc.firstElementChild);

    return xmlDoc;
}

Then change my JavaScript snippet from above like this to transform the xml into json and back:然后像这样从上面更改我的 JavaScript 片段以将 xml 转换为 json 并返回：

// read state on load 
if(window.localStorage.graphState){ 
    var doc = json2html(JSON.parse(localStorage.graphState));   
  var dec = new mxCodec(doc);
  dec.decode(doc.documentElement, graph.getModel());
}

// save state on change
graph.getModel().addListener('change',function(){
        var codec = new mxCodec();      
    window.localStorage.graphState = JSON.stringify(html2json(codec.encode(
      graph.getModel()
    )));
});

如何在页面刷新mxgraph上保留绘制的框和路径

问题描述

1 个解决方案

解决方案1
4 2019-04-27 15:01:17

Update using JSON使用 JSON 更新

如何在页面刷新mxgraph上保留绘制的框和路径

问题描述

1 个解决方案

解决方案1 4 2019-04-27 15:01:17

Update using JSON使用 JSON 更新

解决方案1
4 2019-04-27 15:01:17