{-# LANGUAGE TypeFamilies , FlexibleContexts , UndecidableInstances #-} ----------------------------------------------------------------------------- -- | -- Module : Diagrams.Combinators -- Copyright : (c) 2011 diagrams-lib team (see LICENSE) -- License : BSD-style (see LICENSE) -- Maintainer : diagrams-discuss@googlegroups.com -- -- Higher-level tools for combining diagrams. -- ----------------------------------------------------------------------------- module Diagrams.Combinators ( -- * Unary operations withEnvelope , phantom, strut , pad -- * Binary operations , beneath , beside -- * n-ary operations , appends , position, decorateTrail, decoratePath , cat, cat', CatOpts(..), CatMethod(..) ) where import Graphics.Rendering.Diagrams import Diagrams.Segment (Segment(..)) import Diagrams.Path import Diagrams.Util import Data.AdditiveGroup import Data.VectorSpace import Data.Semigroup import Data.Default ------------------------------------------------------------ -- Working with envelopes ------------------------------------------------------------ -- | Use the envelope from some object as the envelope for a -- diagram, in place of the diagram's default envelope. withEnvelope :: (Backend b (V a), Enveloped a, Monoid' m) => a -> QDiagram b (V a) m -> QDiagram b (V a) m withEnvelope = setEnvelope . getEnvelope -- | @phantom x@ produces a \"phantom\" diagram, which has the same -- envelope as @x@ but produces no output. phantom :: (Backend b (V a), Enveloped a, Monoid' m) => a -> QDiagram b (V a) m phantom a = mkQD nullPrim (getEnvelope a) mempty mempty -- | @pad s@ \"pads\" a diagram, expanding its envelope by a factor of -- @s@ (factors between 0 and 1 can be used to shrink the envelope). -- Note that the envelope will expand with respect to the local -- origin, so if the origin is not centered the padding may appear -- \"uneven\". If this is not desired, the origin can be centered -- (using, e.g., 'centerXY' for 2D diagrams) before applying @pad@. pad :: ( Backend b v , InnerSpace v, OrderedField (Scalar v) , Monoid' m ) => Scalar v -> QDiagram b v m -> QDiagram b v m pad s d = withEnvelope (d # scale s) d -- | @strut v@ is a diagram which produces no output, but with respect -- to alignment and envelope acts like a 1-dimensional segment -- oriented along the vector @v@, with local origin at its center. -- Useful for manually creating separation between two diagrams. strut :: ( Backend b v, InnerSpace v , OrderedField (Scalar v) , Monoid' m ) => v -> QDiagram b v m strut v = phantom . translate ((-0.5) *^ v) . getEnvelope $ Linear v ------------------------------------------------------------ -- Combining two objects ------------------------------------------------------------ -- | @beneath@ is just a convenient synonym for @'flip' 'atop'@; that is, -- @d1 \`beneath\` d2@ is the diagram with @d2@ superimposed on top of -- @d1@. beneath :: (HasLinearMap v, OrderedField (Scalar v), InnerSpace v, Monoid' m) => QDiagram b v m -> QDiagram b v m -> QDiagram b v m beneath = flip atop -- | Place two monoidal objects (/i.e./ diagrams, paths, -- animations...) next to each other along the given vector. In -- particular, place the second object so that the vector points -- from the local origin of the first object to the local origin of -- the second object, at a distance so that their envelopes are just -- tangent. The local origin of the new, combined object is the -- local origin of the first object. -- -- Note that @beside v@ is associative, so objects under @beside v@ -- form a semigroup for any given vector @v@. However, they do -- /not/ form a monoid, since there is no identity element. 'mempty' -- is a right identity (@beside v d1 mempty === d1@) but not a left -- identity (@beside v mempty d1 === d1 # align (negateV v)@). -- -- In older versions of diagrams, @beside@ put the local origin of -- the result at the point of tangency between the two inputs. That -- semantics can easily be recovered by performing an alignment on -- the first input before combining. That is, if @beside'@ denotes -- the old semantics, -- -- > beside' v x1 x2 = beside v (x1 # align v) x2 -- -- To get something like @beside v x1 x2@ whose local origin is -- identified with that of @x2@ instead of @x1@, use @beside -- (negateV v) x2 x1@. beside :: (Juxtaposable a, Semigroup a) => V a -> a -> a -> a beside v d1 d2 = d1 <> juxtapose v d1 d2 -- XXX add picture to above documentation? ------------------------------------------------------------ -- Combining multiple objects ------------------------------------------------------------ -- | @appends x ys@ appends each of the objects in @ys@ to the object -- @x@ in the corresponding direction. Note that each object in -- @ys@ is positioned beside @x@ /without/ reference to the other -- objects in @ys@, so this is not the same as iterating 'beside'. appends :: (Juxtaposable a, Monoid' a) => a -> [(V a,a)] -> a appends d1 apps = d1 <> mconcat (map (\(v,d) -> juxtapose v d1 d) apps) -- | Position things absolutely: combine a list of objects -- (e.g. diagrams or paths) by assigning them absolute positions in -- the vector space of the combined object. position :: (HasOrigin a, Monoid' a) => [(Point (V a), a)] -> a position = mconcat . map (uncurry moveTo) -- | Combine a list of diagrams (or paths) by using them to -- \"decorate\" a trail, placing the local origin of one object at -- each successive vertex of the trail. The first vertex of the -- trail is placed at the origin. If the trail and list of objects -- have different lengths, the extra tail of the longer one is -- ignored. decorateTrail :: (HasOrigin a, Monoid' a) => Trail (V a) -> [a] -> a decorateTrail t = position . zip (trailVertices origin t) -- | Combine a list of diagrams (or paths) by using them to -- \"decorate\" a path, placing the local origin of one object at -- each successive vertex of the path. If the path and list of objects -- have different lengths, the extra tail of the longer one is -- ignored. decoratePath :: (HasOrigin a, Monoid' a) => Path (V a) -> [a] -> a decoratePath p = position . zip (concat $ pathVertices p) -- | Methods for concatenating diagrams. data CatMethod = Cat -- ^ Normal catenation: simply put diagrams -- next to one another (possibly with a -- certain distance in between each). The -- distance between successive diagram -- /envelopes/ will be consistent; the -- distance between /origins/ may vary if -- the diagrams are of different sizes. | Distrib -- ^ Distribution: place the local origins of -- diagrams at regular intervals. With -- this method, the distance between -- successive /origins/ will be consistent -- but the distance between envelopes may -- not be. Indeed, depending on the amount -- of separation, diagrams may overlap. -- | Options for 'cat''. data CatOpts v = CatOpts { catMethod :: CatMethod -- ^ Which 'CatMethod' should be used: -- normal catenation (default), or -- distribution? , sep :: Scalar v -- ^ How much separation should be used -- between successive diagrams -- (default: 0)? When @catMethod = -- Cat@, this is the distance between -- /envelopes/; when @catMethod = -- Distrib@, this is the distance -- between /origins/. , catOptsvProxy__ :: Proxy v -- ^ This field exists solely to aid type inference; -- please ignore it. } -- The reason the proxy field is necessary is that without it, -- altering the sep field could theoretically change the type of a -- CatOpts record. This causes problems when writing an expression -- like @with { sep = 10 }@, because knowing the type of the whole -- expression does not tell us anything about the type of @with@, and -- therefore the @Num (Scalar v)@ constraint cannot be satisfied. -- Adding the Proxy field constrains the type of @with@ in @with {sep -- = 10}@ to be the same as the type of the whole expression. instance Num (Scalar v) => Default (CatOpts v) where def = CatOpts { catMethod = Cat , sep = 0 , catOptsvProxy__ = Proxy } -- | @cat v@ positions a list of objects so that their local origins -- lie along a line in the direction of @v@. Successive objects -- will have their envelopes just touching. The local origin -- of the result will be the same as the local origin of the first -- object. -- -- See also 'cat'', which takes an extra options record allowing -- certain aspects of the operation to be tweaked. cat :: ( Juxtaposable a, Monoid' a, HasOrigin a , InnerSpace (V a), Floating (Scalar (V a)) ) => V a -> [a] -> a cat v = cat' v def -- | Like 'cat', but taking an extra 'CatOpts' arguments allowing the -- user to specify -- -- * The spacing method: catenation (uniform spacing between -- envelopes) or distribution (uniform spacing between local -- origins). The default is catenation. -- -- * The amount of separation between successive diagram -- envelopes/origins (depending on the spacing method). The -- default is 0. -- -- 'CatOpts' is an instance of 'Default', so 'with' may be used for -- the second argument, as in @cat' (1,2) with {sep = 2}@. -- -- Note that @cat' v with {catMethod = Distrib} === mconcat@ -- (distributing with a separation of 0 is the same as -- superimposing). cat' :: ( Juxtaposable a, Monoid' a, HasOrigin a , InnerSpace (V a), Floating (Scalar (V a)) ) => V a -> CatOpts (V a) -> [a] -> a cat' v (CatOpts { catMethod = Cat, sep = s }) = foldB comb mempty where comb d1 d2 = d1 <> (juxtapose v d1 d2 # moveOriginBy vs) vs = withLength s (negateV v) cat' v (CatOpts { catMethod = Distrib, sep = s }) = decorateTrail . fromOffsets . repeat $ withLength s v -- infinite trail, no problem for Haskell =D