Copyright	(c) 2015 Christopher Chalmers
License	BSD-style (see LICENSE)
Maintainer	c.chalmers@me.com
Safe Haskell	None
Language	Haskell2010

Graphics.Potrace.Base

Contents

Tracing
Bitmaps
Parameters

Description

A mid-level interface to potrace. Includes helpers for making bitmap images. This is useful for other libraries that want to implement their own tools on top of potrace (see "potrace-diagrams").

In principle this could be in a separate module but there's already three separate potrace modules and the dependencies aren't huge.

Synopsis

Tracing

data Curve Source

A curve is a list of segments. The starting point is provided for convenience but this is just the final point of the last segment.

Constructors

Curve !P2 [Segment]

data Segment Source

potrace defines a segment as either Bezier or a Corner (in most systems this is equivalent to linear segments).

Constructors

Bezier !P2 !P2 !P2
Corner !P2 !P2

Instances

Read Segment Source
Show Segment Source

data P2 Source

Data type representing a 2D point were the origin is at the bottom left.

Constructors

P2 !Double !Double

Instances

Read P2 Source
Show P2 Source
Storable P2 Source

trace :: Bitmap -> [Curve] Source

Trace the bitmap image to a list of curves using potrace with def parameters.

trace' :: Parameters -> Bitmap -> [Curve] Source

Trace the bitmap image to a list of curves using potrace with given parameters.

traceForest :: Bitmap -> Forest Curve Source

Trace the bitmap image as a forest of curves using potrace with def parameters. Each child curve is completely contained in it's parent.

traceForest' :: Parameters -> Bitmap -> Forest Curve Source

Trace the bitmap image as a forest of curves using potrace with given parameters parameters. Each child curve is completely contained in it's parent.

Bitmaps

data Bitmap Source

Data type to represent a bit packed image. This can be passed to potrace via trace. The constructor is exported by Base but be aware the underlying vector has a host dependant form. You are advised to use generate to create a Bitmap.

Constructors

Bitmap
Fields bitmapWidth :: Int bitmapHeight :: Int bitmapDy :: Int bitmapData :: Vector CULong

generate :: Int -> Int -> (Int -> Int -> Bool) -> Bitmap Source

Given an image and a predicate for whether a pixel is on or off, create a bit-packed image suitable for passing to potrace.

index :: Bitmap -> Int -> Int -> Bool Source

Index a pixel in a Bitmap. This is mainly here for debugging purposes.

Parameters

data Parameters Source

Parameters to control the tracing operation of potrace. The default parameters are

Parameters
  { turdSize     = 2
  , turnPolicy   = MinorityTP
  , alphaMax     = 1.0
  , optTolerance = Just 0.2
  }

Constructors

Parameters
Fields _turdSize :: Int See `turdSize`. _turnPolicy :: TurnPolicy See `turnPolicy`. _alphaMax :: Double See `alphaMax`. _optTolerance :: Maybe Double See `optTolerance`.

Instances

Default Parameters Source

data TurnPolicy Source

How to resolve ambiguities during decomposition of bitmaps into paths.

Constructors

BlackTP	Prefers to connect black (foreground) components
WhiteTP	Prefers to connect white (background) components.
LeftTP	Always take a left turn.
RightTP	Always take a right turn.
MinorityTP	Prefers to connect the color (black or white) that occurs least frequently in a local neighborhood of the current position.
MajorityTP	Prefers to connect the color (black or white) that occurs most frequently in a local neighborhood of the current position. (default)
RandomTP	Choose pseudo-randomly