Copyright	(c) 2011-2015 diagrams-core team (see LICENSE)
License	BSD-style (see LICENSE)
Maintainer	diagrams-discuss@googlegroups.com
Safe Haskell	None
Language	Haskell2010

Diagrams.Core.Style

Contents

Attributes
- Attributes prisms
- Attributes utilities
Styles

Description

A definition of styles for diagrams as extensible, heterogeneous collections of attributes.

Synopsis

Attributes

An attribute is anything that determines some aspect of a diagram's rendering. The standard diagrams library defines several standard attributes (line color, line width, fill color, etc.) but additional attributes may easily be created. Additionally, a given backend need not handle (or even know about) attributes used in diagrams it renders.

The attribute code is inspired by xmonad's Message type, which was in turn based on ideas in:

Simon Marlow. An Extensible Dynamically-Typed Hierarchy of Exceptions. Proceedings of the 2006 ACM SIGPLAN workshop on Haskell. http://research.microsoft.com/apps/pubs/default.aspx?id=67968.

class (Typeable a, Semigroup a) => AttributeClass a Source

Every attribute must be an instance of AttributeClass, which simply guarantees Typeable and Semigroup constraints. The Semigroup instance for an attribute determines how it will combine with other attributes of the same type.

data Attribute v n :: * where Source

An existential wrapper type to hold attributes. Some attributes are simply inert/static; some are affected by transformations; and some are affected by transformations and can be modified generically.

Constructors

Attribute :: AttributeClass a => a -> Attribute v n
MAttribute :: AttributeClass a => Measured n a -> Attribute v n
TAttribute :: (AttributeClass a, Transformable a, V a ~ v, N a ~ n) => a -> Attribute v n

Instances

Typeable * n => Show (Attribute v n)	Shows the kind of attribute and the type contained in the attribute.
Typeable * n => Semigroup (Attribute v n)	Attributes form a semigroup, where the semigroup operation simply returns the right-hand attribute when the types do not match, and otherwise uses the semigroup operation specific to the (matching) types.
(Additive v, Traversable v, Floating n) => Transformable (Attribute v n)	`TAttribute`s are transformed directly, `MAttribute`s have their local scale multiplied by the average scale of the transform. Plain `Attribute`s are unaffected.
Each (Style v n) (Style v' n') (Attribute v n) (Attribute v' n')
type N (Attribute v n) = n
type V (Attribute v n) = v

Attributes prisms

_Attribute :: AttributeClass a => Prism' (Attribute v n) a Source

Prism onto an Attribute.

_MAttribute :: (AttributeClass a, Typeable n) => Prism' (Attribute v n) (Measured n a) Source

Prism onto an MAttribute.

_TAttribute :: (V a ~ v, N a ~ n, AttributeClass a, Transformable a) => Prism' (Attribute v n) a Source

Prism onto a TAttribute.

Attributes utilities

unwrapAttribute :: AttributeClass a => Attribute v n -> Maybe a Source

Unwrap an unknown Attribute type, performing a dynamic (but safe) check on the type of the result. If the required type matches the type of the attribute, the attribute value is returned wrapped in Just; if the types do not match, Nothing is returned.

Measured attributes cannot be extrated from this function until they have been unmeasured with unmeasureAttribute. If you want a measured attibute use the _MAttribute prism.

unmeasureAttribute :: (Num n, Typeable n) => n -> n -> Attribute v n -> Attribute v n Source

Turn an MAttribute into an Attribute using the given global and normalized scale.

attributeType :: Attribute v n -> TypeRep Source

Type of an attribute that is stored with a style. Measured attributes return the type as if it where unmeasured.

Styles

A Style is a heterogeneous collection of attributes, containing at most one attribute of any given type. This is also based on ideas stolen from xmonad, specifically xmonad's implementation of user-extensible state.

newtype Style v n Source

A Style is a heterogeneous collection of attributes, containing at most one attribute of any given type.

Constructors

Style (HashMap TypeRep (Attribute v n))

Instances

Typeable * n => Show (Style v n)	Show the attributes in the style.
Typeable * n => Monoid (Style v n)	The empty style contains no attributes.
Typeable * n => Semigroup (Style v n)	Combine a style by combining the attributes; if the two styles have attributes of the same type they are combined according to their semigroup structure.
Ixed (Style v n)
At (Style v n)
Wrapped (Style v n)
(Additive v, Traversable v, Floating n) => Transformable (Style v n)
Typeable * n => HasStyle (Style v n)
Action (Style v n) m	Styles have no action on other monoids.
Rewrapped (Style v n) (Style v' n')
Each (Style v n) (Style v' n') (Attribute v n) (Attribute v' n')
type Index (Style v n) = TypeRep
type IxValue (Style v n) = Attribute v n
type Unwrapped (Style v n) = HashMap TypeRep (Attribute v n)
type N (Style v n) = n
type V (Style v n) = v

Making styles

attributeToStyle :: Attribute v n -> Style v n Source

Turn an attribute into a style. An easier way to make a style is to use the monoid instance and apply library functions for applying that attribute:

myStyle = mempty # fc blue :: Style V2 Double

Extracting attibutes from styles

getAttr :: forall a v n. AttributeClass a => Style v n -> Maybe a Source

Extract an attribute from a style of a particular type. If the style contains an attribute of the requested type, it will be returned wrapped in Just; otherwise, Nothing is returned.

Trying to extract a measured attibute will fail. It either has to be unmeasured with unmeasureAttrs or use the atMAttr lens.

unmeasureAttrs :: (Num n, Typeable n) => n -> n -> Style v n -> Style v n Source

Replace all MAttributes with Attributes using the global and normalized scales.

Attibute lenses

atAttr :: AttributeClass a => Lens' (Style v n) (Maybe a) Source

Lens onto a plain attribute of a style.

atMAttr :: (AttributeClass a, Typeable n) => Lens' (Style v n) (Maybe (Measured n a)) Source

Lens onto a measured attribute of a style.

atTAttr :: (V a ~ v, N a ~ n, AttributeClass a, Transformable a) => Lens' (Style v n) (Maybe a) Source

Lens onto a transformable attribute of a style.

Applying styles

applyAttr :: (AttributeClass a, HasStyle d) => a -> d -> d Source

Apply an attribute to an instance of HasStyle (such as a diagram or a style). If the object already has an attribute of the same type, the new attribute is combined on the left with the existing attribute, according to their semigroup structure.

applyMAttr :: (AttributeClass a, N d ~ n, HasStyle d, Typeable n) => Measured n a -> d -> d Source

Apply a measured attribute to an instance of HasStyle (such as a diagram or a style). If the object already has an attribute of the same type, the new attribute is combined on the left with the existing attribute, according to their semigroup structure.

applyTAttr :: (AttributeClass a, Transformable a, V a ~ V d, N a ~ N d, HasStyle d) => a -> d -> d Source

Apply a transformable attribute to an instance of HasStyle (such as a diagram or a style). If the object already has an attribute of the same type, the new attribute is combined on the left with the existing attribute, according to their semigroup structure.

class HasStyle a where Source

Type class for things which have a style.

Methods

applyStyle :: Style (V a) (N a) -> a -> a Source

Apply a style by combining it (on the left) with the existing style.

Instances

HasStyle a => HasStyle [a]
(HasStyle a, Ord a) => HasStyle (Set a)
HasStyle b => HasStyle (a -> b)
(HasStyle a, HasStyle b, (~) (* -> ) (V a) (V b), (~) (N a) (N b)) => HasStyle (a, b)
HasStyle a => HasStyle (Map k a)
HasStyle b => HasStyle (Measured n b)
Typeable * n => HasStyle (Style v n)
(Metric v, OrderedField n, Semigroup m) => HasStyle (QDiagram b v n m)