The SVG extension to the Cairo 2D graphics library.

These operations render an SVG image directly in the current Render contect. Because they operate in the cairo Render monad they are affected by the current transformation matrix. So it is possible, for example, to scale or rotate an SVG image.

In the following example we scale an SVG image to a unit square:

let (width, height) = svgGetSize in
do scale (1/width) (1/height)
svgRender svg

With this API there are seperate functions for loading the SVG and rendering it. This allows us to be more effecient in the case that an SVG image is used many times - since it can be loaded just once and rendered many times. With the convenience API above the SVG would be parsed and processed each time it is drawn.

These versions of the SVG loading operations give temporary access to the SVG object within the scope of the handler function. These operations guarantee that the resources for the SVG object are deallocated at the end of the handler block. If this form of resource allocation is too restrictive you can use the GC-managed versions below.

These versions are ofen used in the following style:

withSvgFromFile "foo.svg" $ \svg -> do
...
svgRender svg
...

These versions of the SVG loading operations use the standard Haskell garbage collector to manage the resources associated with the SVG object. As such they are more convenient to use but the GC cannot give strong guarantees about when the resources associated with the SVG object will be released. In most circumstances this is not a problem, especially if the SVG files being used are not very big.