Diagrams.Backend.Canvas

A full-featured rendering backend for diagrams using Canvas. Implemented using the blank-canvas platform.

To invoke the Canvas backend, you have three options.

• You can use the Diagrams.Backend.Canvas.CmdLine module to create standalone executables which will display the diagram in a browser using a web service.
• You can use the renderCanvas function provided by this module, which gives you more programmatic control over when and how images are displayed (making it east to, for example, write a single program that displays multiple images, or one that diaplays images dynamically based on user input, and so on).
• For the most flexiblity you can invoke the renderDia method from Backend instance for Canvas. In particular, renderDia has the generic type

renderDia :: b -> Options b v -> QDiagram b v m -> Result b v

(omitting a few type class contraints). b represents the backend type, v the vector space, and m the type of monoidal query annotations on the diagram. Options and Result are associated data and type families, respectively, which yield the type of option records and rendering results specific to any particular backend. For b ~ Canvas and v ~ R2, we have

data Options Canvas R2 = CanvaseOptions
 { _size :: SizeSpec2D -- ^^ The requested size
 }

data family Render Canvas R2 = C (RenderM ())

type family Result Canvas R2 = Canvas ()

So the type of renderDia resolves to

renderDia :: Canvas -> Options Canvas R2 -> QDiagram Canvas R2 m ->
Canvas()

which you could call like renderDia Canvas (CanvaseOptions (width 250)) myDiagram

Documentation

data Canvas

This data declaration is simply used as a token to distinguish this rendering engine.

Constructors

Canvas

Instances

Eq Canvas

Ord Canvas

Read Canvas

Show Canvas

Typeable * Canvas

Backend Canvas R2

Renderable Text Canvas

Mainable [(String, Diagram Canvas R2)]

Renderable (DImage External) Canvas

Renderable (Path R2) Canvas

Renderable (Trail R2) Canvas

Monoid (Render Canvas R2)

Mainable (Diagram Canvas R2)

Renderable (Segment Closed R2) Canvas

data Options Canvas R2 = CanvasOptions {

• _canvasSize :: SizeSpec2D

}

type Result Canvas R2 = Canvas ()

data Render Canvas R2 = C (RenderM ())

type MainOpts [(String, Diagram Canvas R2)] = (MainOpts (Diagram Canvas R2), DiagramMultiOpts)

type MainOpts (Diagram Canvas R2)

type B = Canvas

data family Options b v

Backend-specific rendering options.

Instances

data Options NullBackend

data Options Canvas R2 = CanvasOptions {

• _canvasSize :: SizeSpec2D

}

renderCanvas :: Int -> SizeSpec2D -> Diagram Canvas R2 -> IO ()