samples/canvases.html

﻿<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Various Charts in GoJS Nodes</title>
  <meta name="description" content="A diagram where each node contains a chart rendered by Chart.js." />
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <!-- Copyright 1998-2019 by Northwoods Software Corporation. -->

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.3/Chart.bundle.min.js"></script>
  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this

      var $ = go.GraphObject.make;

      myDiagram =
        $(go.Diagram, "myDiagramDiv",
          {
            layout: $(go.TreeLayout)
          });

      myDiagram.nodeTemplate =
        $(go.Node, "Vertical",
          $(go.Panel, "Auto",
            $(go.Shape, { fill: "transparent" },
              new go.Binding("stroke", "color")),
            $(go.Picture,
              { width: 300, height: 150, portId: "" },
              new go.Binding("element", "datasets", makeLineChart))
          ),
          $(go.TextBlock,
            { margin: 8 },
            new go.Binding("text"))
        );

      // This Binding conversion function creates a Canvas element for a Picture
      // that has a rendering of a line chart drawn by Chart.js.
      function makeLineChart(datasets, picture) {
        var canvases = document.getElementById("myCanvases");

        canv = document.createElement("canvas");
        canv.width = canv.style.width = "600px";
        canv.height = canv.style.height = "300px";

        // apparently Chart.js expects the Canvas to be in a DIV
        var div = document.createElement("div");
        div.style.position = "absolute";
        div.appendChild(canv);
        // add the DIV/Canvas to the DOM, temporarily
        canvases.appendChild(div);

        var config = {  // Chart.js configuration, including the DATASETS data from the model data
          type: "line",
          data: {
            labels: ["January", "February", "March", "April", "May", "June", "July"],
            datasets: datasets
          },
          options: {
            animation: {
              onComplete: function() {
                var canvases = document.getElementById("myCanvases");
                if (canvases) {  // remove the Canvas that was in the DOM for rendering
                  canvases.removeChild(div);
                }
              }
            }
          }
        };

        new Chart(canv, config);

        return canv;
      }

      myDiagram.model = $(go.GraphLinksModel,
        {
          copiesArrays: true,
          copiesArrayObjects: true,
          nodeDataArray:
            [
              {
                key: 1, text: "Alpha",
                datasets: [{
                  label: "Random data",
                  borderColor: "black",
                  data: makeRandomPoints(8, 10)
                }]
              },
              {
                key: 2, text: "Beta",
                datasets: [{
                  label: "First dataset",
                  fill: false,
                  backgroundColor: "red",
                  borderColor: "red",
                  data: makeRandomPoints(8)
                }, {
                  label: "Second dataset",
                  fill: false,
                  backgroundColor: "blue",
                  borderColor: "blue",
                  data: makeRandomPoints(8)
                }]
              },
              {
                key: 3, text: "Gamma", color: "green",
                datasets: [{
                  label: "some data",
                  fill: false,
                  backgroundColor: "green",
                  borderColor: "green",
                  data: makeRandomPoints()
                }]
              }
            ],
          linkDataArray: [
            { from: 1, to: 2 },
            { from: 1, to: 3 }
          ]
        });
    }

    function makeRandomPoints(num, range) {
      if (!num) num = 20;
      if (!range) range = 100;
      var pts = [];
      for (var i = 0; i < num; i++) {
        pts.push(Math.random() * range);
      }
      return pts;
    }

    function addNode() {
      myDiagram.model.commit(function(m) {
        var firstnode = myDiagram.nodes.first();
        var color = go.Brush.darken(go.Brush.randomColor());
        var data = {
          text: "Node " + (myDiagram.nodes.count + 1),
          color: color,
          datasets: [{
            label: "some data",
            fill: false,
            backgroundColor: color,
            borderColor: color,
            data: makeRandomPoints()
          }]
        };
        m.addNodeData(data);
        if (firstnode) {
          m.addLinkData({ from: firstnode.key, to: m.getKeyForNodeData(data) });
          // new node starts off at same location as the parent node
          var newnode = myDiagram.findNodeForData(data);
          if (newnode) newnode.location = firstnode.location;
        }
      }, "added chart node");
    }
  </script>
</head>
<body onload="init()">
<div id="sample">
  <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:600px"></div>
  <button onclick="addNode()">Add Chart</button>
  <p>
    This app demonstrates using a popular charting library, <a href="https://chartjs.org">Chart.js</a>,
    for rendering charts within nodes.
  </p>
  <p>
    The data for each chart is stored on the node data in the model.  In this case the <code>datasets</code>
    property value has the same properties that are expected by the Chart.js configuration, but you could
    organize the data however you want.
  </p>
  <p>
    The <code>makeLineChart</code> conversion function is used by a <a>Binding</a> on <a>Picture.element</a>
    to generate a Canvas element that can be shown in the node.  Most of the implementation of that function
    is specific to Chart.js.  The rendering requires the Canvas to be in the HTML DOM.  To avoid accumulating
    resources, the configuration of the chart defines an <code>onComplete</code> event handler to
    remove the Canvas element from the DOM.  That allows any future removal of the Node from the Diagram not
    to leave an unused Canvas element behind.
  </p>
  <!-- myCanvases is used by makeLineChart, but need not be seen by the user -->
  <div id="myCanvases" style="position:absolute; top:0px; left:0px; width:0px; height:0px; opacity:0"></div>
</div>
</body>
</html>