Class mxCodec

In order to resolve references, especially forward references, the mxCodec constructor must be given the document that contains the referenced elements.

The following code is used to encode a graph model.

example

var encoder = new mxCodec();
var result = encoder.encode(graph.getModel());
var xml = mxUtils.getXml(result);

Example

Using the code below, an XML document is decoded into an existing model. The document may be obtained using one of the functions in mxUtils for loading an XML file, eg. mxUtils.get, or using mxUtils.parseXml for parsing an XML string.

example

var doc = mxUtils.parseXml(xmlString);
var codec = new mxCodec(doc);
codec.decode(doc.documentElement, graph.getModel());

Example

This example demonstrates parsing a list of isolated cells into an existing graph model. Note that the cells do not have a parent reference so they can be added anywhere in the cell hierarchy after parsing.

example

var xml = '<root><mxCell id="2" value="Hello," vertex="1"><mxGeometry x="20" y="20" width="80" height="30" as="geometry"/></mxCell><mxCell id="3" value="World!" vertex="1"><mxGeometry x="200" y="150" width="80" height="30" as="geometry"/></mxCell><mxCell id="4" value="" edge="1" source="2" target="3"><mxGeometry relative="1" as="geometry"/></mxCell></root>';
var doc = mxUtils.parseXml(xml);
var codec = new mxCodec(doc);
var elt = doc.documentElement.firstChild;
var cells = [];

while (elt != null)
{
  cells.push(codec.decode(elt));
  elt = elt.nextSibling;
}

graph.addCells(cells);

Example

Using the following code, the selection cells of a graph are encoded and the output is displayed in a dialog box.

example

var enc = new mxCodec();
var cells = graph.getSelectionCells();
mxUtils.alert(mxUtils.getPrettyXml(enc.encode(cells)));

Newlines in the XML can be converted to
, in which case a '
' argument must be passed to mxUtils.getXml as the second argument.

Debugging

For debugging I/O you can use the following code to get the sequence of encoded objects:

example

var oldEncode = encode;
encode(obj)
{
  mxLog.show();
  mxLog.debug('mxCodec.encode: obj='+mxUtils.getFunctionName(obj.constructor));

  return oldEncode.apply(this, arguments);
};

Note that the I/O system adds object codecs for new object automatically. For decoding those objects, the constructor should be written as follows:

example

var MyObj(name)
{
  // ...
};