Implement CSS3 transform

[rototor]

I've started implementing CSS3 transform. My primary goal is to get rotate() working. The rest should be relative easy, but I primary need rotate(90deg).

You can view the my current development here https://github.com/rototor/openhtmltopdf/tree/css3-transform-implementation

CSS parsing should be mostly done, but it is not yet applied on the elements. I'll be away for a week on holidays, but will continue to implement this afterwards.

Note, related to #23 I implemented saveSate() and restoreState() - also for Java2D.

[danfickle]

@rototor - Looks good. The hard part is implementing transform origin I think (from memory).

[danfickle]

@rototor - Would you mind submitting a pull request with what you have got and I'll see if I can help with implementation?

Thanks,
Daniel.

P.S I hope you had a wonderful holiday!

[rototor]

@danfickle I sent you a pull request #45. Sorry for the delay, after holiday the usual "we need that and that now" happened in work... had no time yet to look future into this...

[danfickle]

Thanks mate, I'll see how far I get.

[danfickle]

OK, initial support has landed.

What is not supported yet:

• Multiple transforms on the one element.
• Transformed element across pages.
• translate, translateX, translateY, skew, skewX and skewY

What is supported:

• rotate, matrix, scale, scaleX, scaleY
• Transforms on nested elements.
• transform-origin.
• Transforms on the second and subsequent page.

I'll do a release tomorrow so everyone can test it out.

[danfickle]

I thought about this some more, the problem with cross-page transforms is that the page(s) to paint text and other content on is determined by the pre-transform coordinates. We need to use the post transform coordinates.

[danfickle]

All working now.