Convenient creation of command-line-driven executables for rendering diagrams using the cairo backend.
defaultMaincreates an executable which can render a single diagram at various options.
defaultMainbut allows for a list of diagrams from which the user can choose one to render.
defaultMainbut for animations instead of diagrams.
If you want to generate diagrams programmatically---i.e. if you want to do anything more complex than what the below functions provide---you have several options.
- A simple but somewhat inflexible approach is to wrap up
animMain) in a call to
- A more flexible approach is to use the
renderCairofunction provided in the Diagrams.Backend.Cairo module.
- For the most flexibility, you can call the generic
renderDiafunction directly; see Diagrams.Backend.Cairo for more information.
This is the simplest way to render diagrams, and is intended to be used like so:
... other definitions ... myDiagram = ... main = defaultMain myDiagram
Compiling a source file like the above example will result in an
executable which takes command-line options for setting the size,
output file, and so on, and renders
myDiagram with the
On Unix systems, the generated executable also supports a rudimentary "looped" mode, which watches the source file for changes and recompiles itself on the fly.
--help to the generated executable to see all available
options. Currently it looks something like
Command-line diagram generation. Foo [OPTIONS] Common flags: -w --width=INT Desired width of the output image -h --height=INT Desired height of the output image -o --output=FILE Output file -f --fpu=FLOAT Frames per unit time (for animations) -l --loop Run in a self-recompiling loop -s --src=FILE Source file to watch -i --interval=SECONDS When running in a loop, check for changes every n seconds. -? --help Display help message -V --version Print version information
For example, a couple common scenarios include
$ ghc --make MyDiagram # output image.png with a width of 400px (and auto-determined height) $ ./MyDiagram -o image.png -w 400 # output 200x200 dia.pdf, then watch for changes every 10 seconds $ ./MyDiagram -o dia.pdf -h 200 -w 200 -l -i 10
multiMain is like
defaultMain, except instead of a single
diagram it takes a list of diagrams paired with names as input.
The generated executable then takes a
specifying the name of the diagram that should be rendered. The
list of available diagrams may also be printed by passing the
$ ghc --make MultiTest [1 of 1] Compiling Main ( MultiTest.hs, MultiTest.o ) Linking MultiTest ... $ ./MultiTest --list Available diagrams: foo bar $ ./MultiTest --selection bar -o Bar.png -w 200
animMain is like
defaultMain, but renders an animation
instead of a diagram. It takes as input an animation and produces
a command-line program which will crudely "render" the animation
by rendering one image for each frame, named by extending the given
output file name by consecutive integers. For example if the given
output file name is
foo/blah.png, the frames will be saved in
foo/blah002.png, and so on (the number of
padding digits used depends on the total number of frames). It is
up to the user to take these images and stitch them together into
an actual animation format (using, e.g.
Of course, this is a rather crude method of rendering animations; more sophisticated methods will likely be added in the future.
--fpu option can be used to control how many frames will be
output for each second (unit time) of animation.
This data declaration is simply used as a token to distinguish
the cairo backend: (1) when calling functions where the type
inference engine would otherwise have no way to know which
backend you wanted to use, and (2) as an argument to the
Renderable type classes.