Main entry point for command-line diagram creation. This is the method that users will call from their program main. For instance an expected user program would take the following form.

import Diagrams.Prelude
import Diagrams.Backend.TheBestBackend.CmdLine

d :: Diagram B R2
d = ...

main = mainWith d

Most backends should be able to use the default implementation. A different implementation should be used to handle more complex interactions with the user.

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/blah001.png, 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. ffmpeg).

Of course, this is a rather crude method of rendering animations; more sophisticated methods will likely be added in the future.

The --fpu option can be used to control how many frames will be output for each second (unit time) of animation.

gifMain takes a list of diagram and delay time pairs and produces a command line program to generate an animated GIF, with options GifOpts. "Delay times are in 1/100ths of a second."

Example usage:

  $ ghc --make GifTest
  [1 of 1] Compiling Main             ( GifTest.hs, GifTest.o )
  Linking GifTest ...
  ./GifTest --help
  GifTest

  Usage: GifTest [-w|--width WIDTH] [-h|--height HEIGHT] [-o|--output OUTPUT]
  [--dither] [--looping-off] [--loop-repeat ARG]
  Command-line diagram generation.

  Available options:
   -?,--help                Show this help text
   -w,--width WIDTH         Desired WIDTH of the output image
   -h,--height HEIGHT       Desired HEIGHT of the output image
   -o,--output OUTPUT       OUTPUT file
   --dither                 Turn on dithering.
   --looping-off            Turn looping off
   --loop-repeat ARG        Number of times to repeat

Extra options for animated GIFs.

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 Backend and Renderable type classes.