如何使用蜡染获得 SVG 图像的图像大小（宽度/高度）

Question

How can I get the size (width/height) of an SVG image using batik (1.7)?

String s = "https://openclipart.org/download/228858";
InputStream is = new URL(s).openStream();

DocumentBuilderFactory f = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = f.newDocumentBuilder();
Document doc = builder.parse(is);

SVGGeneratorContext ctx = SVGGeneratorContext.createDefault(doc);
SVGGraphics2D svg = new SVGGraphics2D(ctx,false);

Dimension d = svg.getSVGCanvasSize();
Rectangle r = svg.getClipBounds();

System.out.println(svg.toString()); //org.apache.batik.svggen.SVGGraphics2D[font=java.awt.Font[family=Dialog,name=sanserif,style=plain,size=12],color=java.awt.Color[r=0,g=0,b=0]]
System.out.println("Dimension null? "+(d==null)); //true
System.out.println("Rectangle null? "+(r==null)); //true

The example can be directly executed and is downloading a image from open clipart.org. Alternatively to a absolute size I'm also interested in the aspect ratio of the image.

Answer 1

try this code , by the way the SAXparser raises an error in case of the svg image that you passed because the attribute r should be defined for circle element i made my testes on svg samples that come with Batik Batik's samples folder

SAXSVGDocumentFactory factory = new SAXSVGDocumentFactory(
                XMLResourceDescriptor.getXMLParserClassName());

        File file = new File("C:/resources/chessboard.svg");
        InputStream is = new FileInputStream(file);

        Document document = factory.createDocument(
                file.toURI().toURL().toString(), is);
        UserAgent agent = new UserAgentAdapter();
        DocumentLoader loader= new DocumentLoader(agent);
        BridgeContext context = new BridgeContext(agent, loader);
        context.setDynamic(true);
        GVTBuilder builder= new GVTBuilder();
        GraphicsNode root= builder.build(context, document);

        System.out.println(root.getPrimitiveBounds().getWidth());
        System.out.println(root.getPrimitiveBounds().getHeight());

getPrimitiveBounds(): Returns the bounds of the area covered by this node's primitive paint. This is the painted region of fill and stroke but does not account for clipping, masking or filtering

a course explaining batik(useful)

Answer 2

To get the SVG image dimensions and ratio it is also sufficient to check viewBox attribute of an SVG image.

SAXSVGDocumentFactory factory = new SAXSVGDocumentFactory(
    XMLResourceDescriptor.getXMLParserClassName());

File file = new File("C:/resources/chessboard.svg");
InputStream is = new FileInputStream(file);

Document document = factory.createDocument(
    file.toURI().toURL().toString(), is);

String viewBox = document.getDocumentElement().getAttribute("viewBox");
String[] viewBoxValues = viewBox.split(" ");
if (viewBoxValues.length > 3) {
    width = Integer.parseInt(viewBoxValues[2]);
    height = Integer.parseInt(viewBoxValues[3]);
}

In this code we check viewBox attribute and if it is present and has 4 values, we take 3rd (width) and 4th (height).