Libraries for reading and writing vector graphics - polling x,y for color

I'm doing an implementation for a path planning algorithm. I'd really like to be able to load in a 2d "environment" in vector graphics (svg) format, so that complex obstacles can be used. This would also make it fairly easy to overlay the path onto the environment and export another file with the result of the algorithm.

What I'm hoping to be able to do is use some kind of library in my collision test method so that I can simply ask, "is there an obstacle at x, y?" and get back true or false. And then of course I'd like to be able to add the path itself to the file.

A brief search and a couple of downloads left me with libraries which either create 开发者_如何学运维svg's or render them but none really gave me what I need. Am I better off just parsing the xml and hacking through everything manually? That seems like a lot of wasted effort.

1.This may be a bit heavyhanded, but Qt has a really great set of tools called the Graphics View Framework. Using these tools, you can create a bunch of QGraphicsItems (polygons, paths, etc..) in a QGraphicsScene, and then query the scene by giving it a position. Using this you'll never actually have to render the scene out to a raster bitmap. http://doc.trolltech.com/4.2/graphicsview.html, http://doc.trolltech.com/4.2/qgraphicsscene.html#itemAt

2.Cairo has tools to draw all sorts of shapes as well, but I believe you'll have to render the whole image and then check the pixel values. http://cairographics.org/

The SVG specification includes some DOM interfaces for collision detection:

• http://www.w3.org/TR/SVG/struct.html#_svg_SVGSVGElement__getEnclosureList
• http://www.w3.org/TR/SVG/struct.html#_svg_SVGSVGElement__getIntersectionList

Using these methods, all "obstacles" (which can be groups of primitive elements, using the <g> element) should be labelled as a target of pointer events.

These methods are bounding-box based, however, so may not be sophisticated enough for your requirements.

Thanks for the responses. I didn't manage to get anything working in QT (it's massive!) or Cairo, and I ended up going with PNGwriter, which does pretty much what I wanted except, of course, that it reads and writes PNG's instead of vector graphics. The downside here is that my coordinates must be rounded off to even pixels. Maybe I'll continue to look into vector graphics, but this solution is satisfactory for this project.