Batik SVGGraphics2D nullpointerexception when drawing image

Question

I'm trying to use the Batik library to draw a BufferedImage to a SVG file. I have very similar code working fine for EPS/PS files, but for some reason the following code: ``` // Get a DOMImplementation and create an XML document DOMImplementation domImpl = GenericDOMImplementation.getDOMImplementation(); Document document = domImpl.createDocument(null, "svg", null); // Create an instance of the SVG Generator SVGGraphics2D svgGenerator = new SVGGraphics2D(document); // draw from image into the svg: svgGenerator.drawImage(image,new RescaleOp((float)1.0,(float)0.0,null),0,0); // Write svg file OutputStream outputStream = new FileOutputStream(svgFile); Writer out = new OutputStreamWriter(outputStream, "UTF-8"); //svgGenerator.stream(out, true /* use css */); // write and close file: outputStream.flush(); outputStream.close(); ``` Results in a NullPointerException on the svgGenerator.drawImage(...) line. Since basically the same command is working for a AbstractPSDocumentGraphics2D (in ano…

Accepted Answer

For the sake of others googling this... I had - I believe - the same issue.

Assuming Batik 1.7: The low-level cause is: `ImageHandlerBase64Encoder.encodeImage()` calls:

```
ImageWriter writer = ImageWriterRegistry.getInstance().getWriterFor("image/png");
writer.writeImage(buf, os);
```

and the `ImageWriterRegistry` is empty, so it returns null from `getWriterFor("image/png")` hence `writer.writeImage(buf, os);` dies.

The cause of the registry being empty is missing JAR(s) in the Classpath. I think what is specifically required is `batik-codec.jar`, but I just added all the batik JARs.

You can download batik sources and see in debugger that with the JARs the "image/png" and other formats get registered (the first call to `ImageWriterRegistry.getInstance()` creates the instance, its constructor calls `setup()` which in turn iterates over all `ImageWriter` service providers - which should be a non-empty set with the correct Classpath.)

Batik SVGGraphics2D nullpointerexception when drawing image

Solution

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