Batik SVGGraphics2D nullpointerexception when drawing an image

Question

I am trying to use the Batik library to draw a BufferedImage in an SVG file. I have very similar code that works 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 in the svgGenerator.drawImage (...) line. Since in principle the same command works for AbstractPSDocumentGraphics2D (in another method), I have no idea what is wrong here.

Edit: the image is declared elsewhere (class variable, this code is inside the method of this class).

Here is the stacktrace:

 Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at org.apache.batik.svggen.ImageHandlerBase64Encoder.encodeImage(ImageHandlerBase64Encoder.java:157) at org.apache.batik.svggen.ImageHandlerBase64Encoder.handleHREF(ImageHandlerBase64Encoder.java:133) at org.apache.batik.svggen.ImageHandlerBase64Encoder.handleHREF(ImageHandlerBase64Encoder.java:72) at org.apache.batik.svggen.DefaultImageHandler.handleImage(DefaultImageHandler.java:63) at org.apache.batik.svggen.SimpleImageHandler.handleImage(SimpleImageHandler.java:100) at org.apache.batik.svggen.SVGGraphics2D.drawImage(SVGGraphics2D.java:677) at org.apache.batik.svggen.SVGGraphics2D.drawImage(SVGGraphics2D.java:996) at SciTK.SciTK_Image.exportImageAsSVG(SciTK_Image.java:1232) at SciTK.SciTK_Image.save_image(SciTK_Image.java:428) at SciTK.SciTK_Image$7.actionPerformed(SciTK_Image.java:982) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) at javax.swing.AbstractButton.doClick(AbstractButton.java:376) at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833) at com.apple.laf.AquaMenuItemUI.doClick(AquaMenuItemUI.java:157) at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877) at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289) at java.awt.Component.processMouseEvent(Component.java:6505) at javax.swing.JComponent.processMouseEvent(JComponent.java:3321) at java.awt.Component.processEvent(Component.java:6270) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4861) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422) at java.awt.Container.dispatchEventImpl(Container.java:2273) at java.awt.Window.dispatchEventImpl(Window.java:2719) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729) at java.awt.EventQueue.access$200(EventQueue.java:103) at java.awt.EventQueue$3.run(EventQueue.java:688) at java.awt.EventQueue$3.run(EventQueue.java:686) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:702) at java.awt.EventQueue$4.run(EventQueue.java:700) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:699) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) at java.awt.EventDispatchThread.run(EventDispatchThread.java:91) 

Answer 1

For the sake of other googling, this ... I had - I think - the same problem.

Assuming Batik 1.7: the reason is low: ImageHandlerBase64Encoder.encodeImage() calls:

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

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

The reason for the empty registry is the lack of JAR (s) in the Classpath. I think batik-codec.jar specifically required, but I just added all the batik JARs.

You can load batik sources and see in the debugger that "image / png" and other formats are registered with JARs (the first call to ImageWriterRegistry.getInstance() creates an instance, its constructor calls setup() , which, in turn, ImageWriter over all ImageWriter providers services - this should be a nonempty collection with the correct class of path.)