Diagrams.TwoD.Attributes

Diagrams may have attributes which affect the way they are rendered. This module defines Textures (Gradients and Colors) in two dimensions. Like the attributes defined in the Diagrams.Attributes module, all attributes defined here use the Last or Recommend semigroup structure. FillColor and LineColor attributes are provided so that backends that don't support gradients need not be concerned with using textures. Backends should only implement color attributes or textures attributes, not both.

Textures

data Texture n

A Texture is either a color SC, linear gradient LG, or radial gradient RG. An object can have only one texture which is determined by the Last semigroup structure.

Constructors

SC SomeColor

LG (LGradient n)

RG (RGradient n)

Instances

Floating n => Transformable (Texture n)

type V (Texture n) = V2

type N (Texture n) = n

solid :: Color a => a -> Texture n

Convert a solid colour into a texture.

_SC :: forall n. Prism' (Texture n) SomeColor

_AC :: Prism' (Texture n) (AlphaColour Double)

Prism onto an AlphaColour Double of a SC texture.

_LG :: forall n. Prism' (Texture n) (LGradient n)

_RG :: forall n. Prism' (Texture n) (RGradient n)

defaultLG :: Fractional n => Texture n

A default is provided so that linear gradients can easily be created using lenses. For example, lg = defaultLG & lGradStart .~ (0.25 ^& 0.33). Note that no default value is provided for lGradStops, this must be set before the gradient value is used, otherwise the object will appear transparent.

defaultRG :: Fractional n => Texture n

A default is provided so that radial gradients can easily be created using lenses. For example, rg = defaultRG & rGradRadius1 .~ 0.25. Note that no default value is provided for rGradStops, this must be set before the gradient value is used, otherwise the object will appear transparent.

data GradientStop d

A gradient stop contains a color and fraction (usually between 0 and 1)

Constructors

GradientStop

Fields

_stopColor :: SomeColor

_stopFraction :: d

stopColor :: Lens' (GradientStop n) SomeColor

A color for the stop.

stopFraction :: Lens' (GradientStop n) n

The fraction for stop.

mkStops :: [(Colour Double, d, Double)] -> [GradientStop d]

A convenient function for making gradient stops from a list of triples. (An opaque color, a stop fraction, an opacity).

data SpreadMethod

The SpreadMethod determines what happens before lGradStart and after lGradEnd. GradPad fills the space before the start of the gradient with the color of the first stop and the color after end of the gradient with the color of the last stop. GradRepeat restarts the gradient and GradReflect restarts the gradient with the stops in reverse order.

Constructors

GradPad

GradReflect

GradRepeat

lineLGradient :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => LGradient n -> a -> a

Apply a linear gradient.

lineRGradient :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => RGradient n -> a -> a

Apply a radial gradient.

Linear Gradients

data LGradient n

Linear Gradient

Constructors

LGradient

Fields

_lGradStops :: [GradientStop n]

_lGradStart :: Point V2 n

_lGradEnd :: Point V2 n

_lGradTrans :: Transformation V2 n

_lGradSpreadMethod :: SpreadMethod

Instances

Fractional n => Transformable (LGradient n)

type V (LGradient n) = V2

type N (LGradient n) = n

lGradStops :: Lens' (LGradient n) [GradientStop n]

A list of stops (colors and fractions).

lGradTrans :: Lens' (LGradient n) (Transformation V2 n)

A transformation to be applied to the gradient. Usually this field will start as the identity transform and capture the transforms that are applied to the gradient.

lGradStart :: Lens' (LGradient n) (Point V2 n)

The starting point for the first gradient stop. The coordinates are in local units and the default is (-0.5, 0).

lGradEnd :: Lens' (LGradient n) (Point V2 n)

The ending point for the last gradient stop.The coordinates are in local units and the default is (0.5, 0).

lGradSpreadMethod :: Lens' (LGradient n) SpreadMethod

For setting the spread method.

mkLinearGradient :: Num n => [GradientStop n] -> Point V2 n -> Point V2 n -> SpreadMethod -> Texture n

Make a linear gradient texture from a stop list, start point, end point, and SpreadMethod. The lGradTrans field is set to the identity transfrom, to change it use the lGradTrans lens.

Radial Gradients

data RGradient n

Radial Gradient

Constructors

RGradient

Fields

_rGradStops :: [GradientStop n]

_rGradCenter0 :: Point V2 n

_rGradRadius0 :: n

_rGradCenter1 :: Point V2 n

_rGradRadius1 :: n

_rGradTrans :: Transformation V2 n

_rGradSpreadMethod :: SpreadMethod

Instances

Fractional n => Transformable (RGradient n)

type V (RGradient n) = V2

type N (RGradient n) = n

rGradStops :: Lens' (RGradient n) [GradientStop n]

A list of stops (colors and fractions).

rGradTrans :: Lens' (RGradient n) (Transformation V2 n)

A transformation to be applied to the gradient. Usually this field will start as the identity transform and capture the transforms that are applied to the gradient.

rGradCenter0 :: Lens' (RGradient n) (Point V2 n)

The center point of the inner circle.

rGradRadius0 :: Lens' (RGradient n) n

The radius of the inner cirlce in local coordinates.

rGradCenter1 :: Lens' (RGradient n) (Point V2 n)

The center of the outer circle.

rGradRadius1 :: Lens' (RGradient n) n

The radius of the outer circle in local coordinates.

rGradSpreadMethod :: Lens' (RGradient n) SpreadMethod

For setting the spread method.

mkRadialGradient :: Num n => [GradientStop n] -> Point V2 n -> n -> Point V2 n -> n -> SpreadMethod -> Texture n

Make a radial gradient texture from a stop list, radius, start point, end point, and SpreadMethod. The rGradTrans field is set to the identity transfrom, to change it use the rGradTrans lens.

Line texture

newtype LineTexture n

The texture with which lines are drawn. Note that child textures always override parent textures. More precisely, the semigroup structure on line texture attributes is that of Last.

Constructors

LineTexture (Last (Texture n))

Instances

Semigroup (LineTexture n)

Default (LineTexture n)

Typeable * n => AttributeClass (LineTexture n)

Floating n => Transformable (LineTexture n)

type V (LineTexture n) = V2

type N (LineTexture n) = n

_LineTexture :: Iso (LineTexture n) (LineTexture n') (Texture n) (Texture n')

getLineTexture :: LineTexture n -> Texture n

lineTexture :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => Texture n -> a -> a

lineTextureA :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => LineTexture n -> a -> a

mkLineTexture :: Texture n -> LineTexture n

_lineTexture :: (Floating n, Typeable n) => Lens' (Style V2 n) (Texture n)

Line color

lineColor :: (InSpace V2 n a, Color c, Typeable n, Floating n, HasStyle a) => c -> a -> a

Set the line (stroke) color. This function is polymorphic in the color type (so it can be used with either Colour or AlphaColour), but this can sometimes create problems for type inference, so the lc and lcA variants are provided with more concrete types.

lc :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => Colour Double -> a -> a

A synonym for lineColor, specialized to Colour Double (i.e. opaque colors). See comment in lineColor about backends.

lcA :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => AlphaColour Double -> a -> a

A synonym for lineColor, specialized to AlphaColour Double (i.e. colors with transparency). See comment in lineColor about backends.

Fill texture

newtype FillTexture n

The texture with which objects are filled. The semigroup structure on fill texture attributes is that of 'Recommed . Last'.

Constructors

FillTexture (Recommend (Last (Texture n)))

Instances

Semigroup (FillTexture n)

Default (FillTexture n)

Typeable * n => AttributeClass (FillTexture n)

Floating n => Transformable (FillTexture n)

type V (FillTexture n) = V2

type N (FillTexture n) = n

_FillTexture :: Iso' (FillTexture n) (Recommend (Texture n))

getFillTexture :: FillTexture n -> Texture n

fillTexture :: (InSpace V2 n a, Typeable n, Floating n, HasStyle a) => Texture n -> a -> a

mkFillTexture :: Texture n -> FillTexture n

_fillTexture :: (Typeable n, Floating n) => Lens' (Style V2 n) (Texture n)

Commit a fill texture in a style. This is not a valid setter because it doesn't abide the functor law (see committed).

_fillTextureR :: (Typeable n, Floating n) => Lens' (Style V2 n) (Recommend (Texture n))

Lens onto the Recommend of a fill texture in a style.

Fill color

fillColor :: (InSpace V2 n a, Color c, Typeable n, Floating n, HasStyle a) => c -> a -> a

Set the fill color. This function is polymorphic in the color type (so it can be used with either Colour or AlphaColour), but this can sometimes create problems for type inference, so the fc and fcA variants are provided with more concrete types.

fc :: (InSpace V2 n a, Floating n, Typeable n, HasStyle a) => Colour Double -> a -> a

A synonym for fillColor, specialized to Colour Double (i.e. opaque colors). See comment after fillColor about backends.

fcA :: (InSpace V2 n a, Floating n, Typeable n, HasStyle a) => AlphaColour Double -> a -> a

A synonym for fillColor, specialized to AlphaColour Double (i.e. colors with transparency). See comment after fillColor about backends.

recommendFillColor :: (InSpace V2 n a, Color c, Typeable n, Floating n, HasStyle a) => c -> a -> a

Set a "recommended" fill color, to be used only if no explicit calls to fillColor (or fc, or fcA) are used. See comment after fillColor about backends.

Compilation utilities

splitTextureFills :: forall b v n a. (Typeable v, Typeable n) => RTree b v n a -> RTree b v n a

Push fill attributes down until they are at the root of subtrees containing only loops. This makes life much easier for backends, which typically have a semantics where fill attributes are applied to linesnon-closed paths as well as loopsclosed paths, whereas in the semantics of diagrams, fill attributes only apply to loops.