生成 SVG

GoJS has one function for creating SVG: Diagram.makeSvg, which returns a new SVGElement with a representation of a GoJS Diagram. The method has a single argument, a JavaScript Object that contains several definable properties, enumerated in the documentation.

This page is almost identical to the page on Making Images, which shows how to render PNG images instead of SVG elements.

Below are several examples of using Diagram.makeSvg on the following diagram:

  // define a simple Node template (but use the default Link template)
  diagram.nodeTemplate =
    $(go.Node, "Auto",
      $(go.Shape, "RoundedRectangle",
        // Shape.fill is bound to Node.data.color
        new go.Binding("fill", "color")),
      $(go.TextBlock,
        { margin: 3 },  // some room around the text
        // TextBlock.text is bound to Node.data.key
        new go.Binding("text", "key"))
    );

  // create the model data that will be represented by Nodes and Links
  var nodeDataArray = [
    { key: "Alpha", color: "lightblue" },
    { key: "Beta", color: "orange" },
    { key: "Gamma", color: "lightgreen" },
    { key: "Delta", color: "pink" }
  ];
  var linkDataArray = [
    { from: "Alpha", to: "Beta" },
    { from: "Alpha", to: "Gamma" },
    { from: "Beta", to: "Beta" },
    { from: "Gamma", to: "Delta" },
    { from: "Delta", to: "Alpha" }
  ];
  diagram.model = new go.GraphLinksModel(nodeDataArray, linkDataArray);
  window.myDiagram = diagram;

Calling makeSvg with no arguments or with an empty properties object results in a scene that is the same size as the Diagram's viewport.

myDiagram.makeSvg();

Calling makeSvg with an object that has the "scale" property set to 1 results in a scene that includes the whole diagram, not just the area visible in the viewport. However, the empty areas around the document bounds are trimmed away.

myDiagram.makeSvg({
  scale: 1
});

Setting the scale property will create a scaled SVG Scene that is precisely large enough to contain the Diagram. The following SVG is created with a scale of 2.

myDiagram.makeSvg({
  scale: 2
});

Note how, unlike an image, you can select the text.

The following SVG is created by setting the size option of makeSvg. Note that the canvas is scaled uniformly and any extra space is placed on the bottom or right side of the SVG.

myDiagram.makeSvg({
  size: new go.Size(100,100)
});

The following SVG is also created by setting the size option of makeSvg, but only the width is set. The height will be whatever size is needed to uniformly contain the Diagram.

myDiagram.makeSvg({
  size: new go.Size(100,NaN)
});

The parts option allows us to specify an Iterable collection of Parts to draw. This is useful if you only want to make an image of part of the diagram, such as a selection of nodes.

  myPartsList = new go.List();
  myPartsList.add(myDiagram.findNodeForKey("Beta"));
  myPartsList.add(myDiagram.findNodeForKey("Delta"));

myDiagram.makeSvg({
  parts: myPartsList
});

Or drawing only the links:

myDiagram.makeSvg({
  parts: myDiagram.links
});

Setting both scale and size creates an image that is scaled specifically and cropped to the given size, as in the following image.

myDiagram.makeSvg({
  scale: 1.5,
  size: new go.Size(100,100)
});

We may want a very large, scaled image that has a limit on its size, and we can use the maxSize property to constrain one or both dimensions. The following image has a very large scale applied but is limited in size horizontally, so some horizontal cropping will occur.

The default value for maxSize is go.Size(2000, 2000), and specifying go.Size(600, NaN) is equivalent to specifying go.Size(600, 2000). If we wanted no cropping on the height we could instead write go.Size(600, Infinity).

myDiagram.makeSvg({
  scale: 9,
  maxSize: new go.Size(600, NaN)
});

Setting both position and size creates a diagram image that is positioned specifically and cropped to the given size. When a position is set but no scale is set, the scale defaults to 1.

myDiagram.makeSvg({
  position: new go.Point(20,20),
  size: new go.Size(50,50)
});

Setting the background to a CSS color string will replace the transparent Diagram background with the given color.

myDiagram.makeSvg({
  size: new go.Size(NaN,250),
  background: "rgba(0, 255, 0, 0.5)" // semi-transparent green background
});

In the following code we use the document bounds to split the Diagram into four equal parts, making four images out of each part. In this way we can prepare images for pagination, making a gallery, or printing purposes. The four images created are shown below.

    var d = myDiagram.documentBounds;
    var halfWidth = d.width / 2;
    var halfHeight = d.height / 2;
    svg = myDiagram.makeSvg({
            position: new go.Point(d.x, d.y),
            size: new go.Size(halfWidth,halfHeight)
          });
    addSVG(svg); // Adds the SVG to a DIV below

    svg = myDiagram.makeSvg({
            position: new go.Point(d.x + halfWidth, d.y),
            size: new go.Size(halfWidth,halfHeight)
          });
    addSVG(svg);

    svg = myDiagram.makeSvg({
            position: new go.Point(d.x, d.y+ halfHeight),
            size: new go.Size(halfWidth,halfHeight)
          });
    addSVG(svg);

    svg = myDiagram.makeSvg({
            position: new go.Point(d.x + halfWidth, d.y + halfHeight),
            size: new go.Size(halfWidth,halfHeight)
          });
    addSVG(svg);

You can open the SVG in a new window by appending it to the DOM of a new page:

var button = document.getElementById('openSVG');
button.addEventListener('click', function() {
  var newWindow = window.open("","newWindow");
  if (!newWindow) return;
  var newDocument = newWindow.document;
  var svg = myDiagram.makeSvg({
    document: newDocument,  // create SVG DOM in new document context
    scale: 9,
    maxSize: new go.Size(600, NaN)
  });
  newDocument.body.appendChild(svg);
}, false);

生成 SVG

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