Custom behavior for strokepath and fillpath

You can customize the behvaiour of the functions that "paint" the current path to the drawing, such as strokepath , strokepreserve , fillpath, and fillpreserve.

Luxor provides a way to add some custom behaviour to the standard operation of these functions.

Internally, these four functions are defined so that they can be connected to a different function using a dispatcher facility. For example, the Luxor function fillpath() is defined as:

fillpath() = fillpath(DISPATCHER[1])fillpath(::DefaultLuxor) = Cairo.fill(_get_current_cr())fillpath(::LDispatcher) = fillpath(DefaultLuxor())

DISPATCHER[1] is defined as an instance of a struct (with no fields) DefaultLuxor.

The datatype DefaultLuxor is a subtype of LDispatcher.

DISPATCHER as such is defined as an array of LDispatcher. This is to make it mutable. Only the first element i.e. DISPATCHER[1] is ever used.

To add some custom behavior for these functions, do the following:

1. Define a new struct MyDispatcher <: Luxor.LDispatcher (it needn't have any fields).

2. Define the function that dispatches on the above struct and

does what you want it to do.

1. Finally, change Luxor.DISPATCHER[1] to an instance of your struct.

Here's an example that changes the behavior of all calls to strokepath() such that the current color is printed to the terminal just before each path is stroked.

struct MyDispatcher <: Luxor.LDispatcher end# define your own strokepath() functionfunction Luxor.strokepath(::MyDispatcher)    # new behavior     println("$(Luxor.get_current_color())")    # you can call the default behavior too    return Luxor.strokepath(Luxor.DefaultLuxor())endLuxor.DISPATCHER[1] = MyDispatcher()@draw begin    for i in 1:20        randomhue()        star(rand(BoundingBox()), 30, 6, 0.5, action = :stroke)    endend

Now, all calls to strokepath() - whether explicitly called or through other functions (for example, with the :stroke action) - will print the current color in the REPL just before the path is stroked.

Similar dispatches can be written for strokepreserve, fillpath, fillpreserve, clip, clippreserve, and paint.

Functions which don't have methods defined for the types will default to calling funcname(Luxor.DefaultLuxor())