NullPointerException when using EMFGraphics2D without writeHeader

[laeubi]

EMFGraphics2D g2 = new EMFGraphics2D(new FileOutputStream(new File("/tmp/test.emf")), new Dimension(800, 600));
BasicStroke basicStroke = new BasicStroke(2f);
g2.setStroke(basicStroke);
g2.setColor(Color.RED);
g2.draw(new Line2D.Double(0, 0, 800, 600));
g2.dispose();

The culprit is that the os field of the class is null.

It works when invoking writeHeader() first.
Imo there are two options:

• Call writeHeader() if the stream is first fetched
• Throw a meaningfull exception

The same applies imo for the disposal... if the inital Graphics2D is disposed, writeTrailer and at least flush should be called on the stream.