Draw high quality HTML to Graphics2D (analogous to drawString())

Question

I know how to draw HTML to a Graphics2D object using Swing's limited built-in HTML support (see http://www.java.net/node/680674), but I need better rendering. Most importantly for this particular chemistry diagram drawing application, Swing's HTML support does not extend to nested sub/superscripts. Better CSS support would be nice too. I don't need image embedding or interactive features such as Javascript or hotlinks.

The HTML text is scaled and rotated and then drawn into a diagram that presumably contains additional text and graphics. The Graphics2D target may be the screen, a printer, or (via iText) a PDF file. I doubt that any solution involving conversion via a BufferedImage or the like can be adequately compact when producing PDF files of publication quality.

My (possibly incorrect) impression is that JavaFX 2.0 does not yet have a solution to this, though it might eventually. (If an earlier version can do this, that might be a solution.) Rewriting the entire application from Swing to JavaFX is not realistic.

This application is free and open source, so any tool it uses probably needs to be freely distributable also. Otherwise, I believe JWebEngine might have fit the bill.

Any help would be appreciated.

Answer 1

You could use a JavaFX WebView node - it has very good HTML tag and css support. You can rotate and scale the WebView node using JavaFX primitives. MathJax can be used within WebView to get high quality equation rendering (if just plain html and css alone doesn't do the job for you). Using JavaFX 2.2, you can take a snapshot of the WebView node and render it to a JavaFX image. You can convert that JavaFX image to an awt BufferedImage using JavaFX 2.2 SwingFXUtils and write it out to a file in many formats using ImageIO.

Here is an example of rendering a piechart node to a png. Depending on the complexity of your html, sometimes an high quality image will compress well to (for example) a png file. In the pichart sample, the 2000x2000 pixel piechart with text and colored gradients saved to a png file of 168kb.

Rewriting the entire application from Swing to JavaFX is not necessary as JavaFX includes the JFXPanel for embedding JavaFX applications inside existing Swing applications. The node snapshot step does not even require the node to be rendered to a screen (it can all be done through memory buffers) - though the JavaFX system would probably need to have been initiated and launched in a JavaFX application or a JFXPanel first.

All of the above may or may not end up giving you the result you want, but it seems a promising avenue to examine.

Update

I ran a couple of tests on this and though I can snapshot a WebView displayed on the screen as explained in this post, due to some limitation of JavaFX 2.2, I was unable to snapshot a WebView displayed as part of an offscreen scene. This means that the information in this answer is accurate, but only applies to the portion of the HTML which can be displayed in the WebView on a screen; e.g. the technique will not currently work for large documents whose pixel size exceeds the screen pixel size. For some sample code, see https://forums.oracle.com/forums/thread.jspa?threadID=2456191.