easyrender (empty) → 0.1.0.0
raw patch · 8 files changed
+3016/−0 lines, 8 filesdep +basedep +bytestringdep +containersbuild-type:Customsetup-changedbinary-added
Dependencies added: base, bytestring, containers, mtl, superdoc, zlib
Files
- ChangeLog +10/−0
- Graphics/EasyRender.hs +288/−0
- Graphics/EasyRender/Auxiliary.hs +51/−0
- Graphics/EasyRender/Internal.hs +1903/−0
- LICENSE +675/−0
- Setup.hs +2/−0
- easyrender.cabal +87/−0
- images/textbox.png binary
+ ChangeLog view
@@ -0,0 +1,10 @@+ChangeLog++v0.1.0.0 2013/12/14+ (2013/12/15) PS1 - converted to Cabal package.++Release 2013/09/02+ Released as part of Quipper 0.5 (no changes).++Release 2013/06/19+ Initial public release, as part of Quipper 0.4.
+ Graphics/EasyRender.hs view
@@ -0,0 +1,288 @@+{-# LANGUAGE TypeSynonymInstances #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE MultiParamTypeClasses #-}+{-# LANGUAGE FunctionalDependencies #-}+{-# LANGUAGE UndecidableInstances #-}+{-# LANGUAGE FlexibleContexts #-}++-- | This module provides efficient functions for rendering vector+-- graphics to a number of formats, including EPS, PostScript, and+-- PDF. It provides an abstraction for multi-page documents, as well+-- as a set of graphics primitives for page descriptions. +-- +-- The graphics model is similar to that of the PostScript and PDF+-- languages, but we only implement a subset of their functionality.+-- Care has been taken that graphics rendering is done efficiently and+-- as lazily as possible; documents are rendered \"on the fly\",+-- without the need to store the whole document in memory.+-- +-- The provided document description model consists of two separate+-- layers of abstraction:+-- +-- * /drawing/ is concerned with placing marks on a fixed surface, and+-- takes place in the 'Draw' monad;+-- +-- * /document structure/ is concerned with a sequence of pages, their+-- bounding boxes, and other meta-data. It takes place in the+-- 'Document' monad.++module Graphics.EasyRender (+ -- * Types+ -- ** Coordinates+ X,+ Y,+ -- ** Color+ Color(..),+ + -- ** Fonts+ Basefont(..),+ Font(..),+ nominalsize,+ text_width,+ + -- ** Alignment+ Alignment,+ align_left,+ align_center,+ align_right,+ + -- * The Document monad+ -- $DOCUMENTMODEL+ Document,+ newpage,+ newpage_defer,+ endpage,+ + -- * The Draw monad + -- $DRAWINGMODEL+ Draw,+ + -- ** Path construction commands+ -- $PATHCONSTRUCTION+ newpath,+ moveto,+ lineto,+ curveto,+ closepath,+ arc,+ arc_append,+ oval,+ rectangle,+ + -- ** Painting commands+ stroke,+ fill,+ fillstroke,+ + -- ** Text commands+ textbox,+ + -- ** Graphics parameters+ -- $GRAPHICSPARAMETERS+ setlinewidth,+ setcolor,+ + -- ** Coordinate system+ -- $COORDINATESYSTEM+ translate,+ scale,+ + -- ** Comments+ comment,+ + -- ** Block structure+ -- $BLOCKSTRUCTURE+ block,+ + -- * Backends+ -- $BACKENDS+ RenderFormat(..),+ render_stdout,+ render_file,+ render_string,+ + -- * Customization+ -- $CUSTOMIZATION+ + -- ** Custom drawing commands+ -- $CUSTOMCOMMANDS+ draw_subroutine,+ custom_ps, + custom_pdf,+ custom_ascii,++ -- ** Customization interface+ Custom(..),+ custom,+ + -- ** Customized rendering functions+ -- $CUSTOMRENDER+ render_custom_stdout,+ render_custom_file,+ render_custom_string,+ ) where++import Graphics.EasyRender.Internal++-- $DOCUMENTMODEL +-- +-- Document description takes place in the 'Document' monad. A basic+-- multi-page document has the following structure:+-- +-- > document :: Document ()+-- > document = do+-- > newpage x y $ do+-- > <<<drawing commands>>>+-- > newpage x y $ do+-- > <<<drawing commands>>>+-- > ...+-- +-- Here, each 'newpage' command describes one page of the+-- document. The parameters /x/ and /y/ specify the dimensions of the+-- page bounding box. They are expressed in units of PostScript+-- points, i.e., multiples of 1/72 inch.+-- +-- Sometimes the bounding box for a page is not known until after the+-- page content has been generated. For this purpose, we also provide+-- the following alternative to the 'newpage' command:+-- +-- > newpage_defer $ do+-- > <<<drawing commands>>>+-- > endpage x y+-- +-- It works just like the 'newpage' command, except that the bounding+-- box is given at the end.++-- $DRAWINGMODEL +-- +-- The description of the visible content of a page take place in the+-- 'Draw' monad. It takes the form of a sequence of drawing commands,+-- for example:+-- +-- > moveto 10 10+-- > lineto 10 100+-- > lineto 100 100+-- > lineto 100 10+-- > closepath+-- > stroke+-- +-- The graphics model is similar to that of the PostScript and PDF+-- languages. The basic concept is that of a /path/, which is a+-- sequence of straight and curved line segments. Paths are first+-- constructed using /path construction commands/, and then painted+-- using /painting commands/, depending on a set of current +-- /graphics parameters/ and a current /coordinate system/.+-- +-- We also provide block structure. Changes to the graphics state+-- (color, coordinate system, etc.) that are done within a block are+-- local to the block.+-- +-- > block $ do+-- > <<drawing commands>>++-- $PATHCONSTRUCTION+-- +-- During path construction, there is a notion of /current path/ and+-- /current point/. A path may consist of zero or more connected+-- subpaths, and each subpath is either open or closed. ++-- $GRAPHICSPARAMETERS+-- +-- The painting commands rely on a set of graphics parameters. The+-- graphics parameters are initially set to default values, and can be+-- altered with the following commands.++-- $COORDINATESYSTEM+-- +-- Coordinates, lengths, widths, etc, are all interpreted relative to+-- a /current coordinate system/. The initial coordinate system of+-- each page has the origin in the lower left corner, with each unit+-- equaling one PostScript point (1/72 inch). The following commands+-- can be used to change the current coordinate system.++-- $BLOCKSTRUCTURE +-- +-- Drawing operations can be grouped into blocks with the 'block'+-- operator. Changes to the graphics parameters and coordinate system+-- are local to the block. It is undefined whether changes to the+-- current path made within a block persist after the end of the block+-- (they do in PDF, but not in PostScript). Therefore, path+-- construction should not be broken up across end-of-block boundaries.++-- $CUSTOMIZATION+-- +-- The document and drawing abstractions provided by this module are+-- purposely kept general-purpose, and do not include+-- application-specific features. However, we provide a mechanism by+-- which applications can provide customized drawing commands and+-- other custom features.++-- $CUSTOMCOMMANDS+-- +-- It is sometimes useful to use customized drawing commands. For+-- example, an application that draws many rectangles might like to+-- define a custom 'rectangle' function for appending a rectangle to+-- the current path. Of course this can be defined as an ordinary+-- Haskell function, using elementary drawing commands:+-- +-- > my_rect :: X -> Y -> X -> Y -> Draw ()+-- > my_rect x0 y0 x1 y1 = do+-- > moveto x0 y0+-- > lineto x0 y1+-- > lineto x1 y1+-- > lineto x1 y0+-- > closepath+-- +-- However, sometimes it is nice to make use of specialized abilities+-- of individual backends. For example, PDF already has a built-in+-- rectangle drawing command, and PostScript has the ability to define+-- custom subroutines within the document text. Using these features+-- can decrease the size of the generated documents. +-- +-- We therefore provide a facility for defining new drawing commands+-- with backend-specific implementations. For example, a more general+-- version of the above 'my_rect' function can be defined as+-- follows:+-- +-- > my_rect :: X -> Y -> X -> Y -> Draw ()+-- > my_rect x0 y0 x1 y1 = draw_subroutine alt $ do+-- > moveto x0 y0+-- > lineto x0 y1+-- > lineto x1 y1+-- > lineto x1 y0+-- > closepath+-- > where+-- > alt = [+-- > custom_ps $ printf "%f %f %f %f rect\n" x0 y0 x1 y1,+-- > custom_pdf $ printf "%f %f %f %f re\n" x0 y0 (x1-x0) (y1-y0),+-- > custom_ascii $ printf "My_rect %f %f %f %f\n" x0 y0 x1 y1+-- > ]+-- +-- The idea is to provide a default definition in terms of primitive+-- drawing commands, as well as a list of various backend specific+-- definitions. In the case of PostScript subroutines, the PostScript+-- file must then also be supplied with a definition for the /rect/+-- subroutine, which can be done with the command 'render_ps_custom':+-- +-- > my_ps_defs = "/rect { ... } bind def\n"+-- >+-- > my_render_ps = render_ps_custom custom { ps_defs = my_ps_defs }+-- +-- Note that the 'draw_subroutine' customization mechanism is entirely+-- optional. Its purpose is to generate shorter output for some+-- backends; if it is omitted, the file may be be longer but should+-- look the same.++-- $BACKENDS +-- +-- The following commands can be used to render documents to various+-- available formats. The available formats are PostScript, PDF, EPS,+-- and an ASCII-based debugging format. Output can be written to+-- standard output, to a file, or to a string.+ +-- $CUSTOMRENDER+-- +-- The following are versions of the generic rendering functions that+-- also take a customization data structure as an additional+-- parameter.+
+ Graphics/EasyRender/Auxiliary.hs view
@@ -0,0 +1,51 @@+{-# LANGUAGE MultiParamTypeClasses #-}+{-# LANGUAGE FunctionalDependencies #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE UndecidableInstances #-}++-- | This module provides miscellaneous general-purpose auxiliary+-- functions used by the "Graphics.EasyRender" package.++module Graphics.EasyRender.Auxiliary where++-- ----------------------------------------------------------------------+-- * Arithmetic operations+ +-- | A version of the 'ceiling' function that returns an 'Integer'.+int_ceiling :: RealFrac a => a -> Integer+int_ceiling = toInteger . ceiling++-- ----------------------------------------------------------------------+-- * The Curry type class++-- | The 'Curry' type class is used to implement functions that have a+-- variable number of arguments. It provides a family of type+-- isomorphisms+-- +-- @fun ≅ args -> res,@+-- +-- where+-- +-- > fun = a1 -> a2 -> ... -> an -> res,+-- > args = (a1, (a2, (..., (an, ())))).++class Curry fun args res | args res -> fun where+ -- | Multiple curry: map a function + -- (/a/[sub 1], (/a/[sub 2], (…, ())) → /b/ + -- to its curried form + -- /a/[sub 1] → /a/[sub 2] → … → /b/.+ mcurry :: (args -> res) -> fun+ -- | Multiple uncurry: map a function+ -- /a/[sub 1] → /a/[sub 2] → … → /b/+ -- to its uncurried form + -- (/a/[sub 1], (/a/[sub 2], (…, ())) → /b/.+ muncurry :: fun -> (args -> res)+ +instance Curry b () b where+ mcurry g = g ()+ muncurry x = const x++instance Curry fun args res => Curry (a -> fun) (a,args) res where+ mcurry g x = mcurry (\xs -> g (x,xs))+ muncurry f (x,xs) = muncurry (f x) xs+
+ Graphics/EasyRender/Internal.hs view
@@ -0,0 +1,1903 @@+{-# LANGUAGE TypeSynonymInstances #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE MultiParamTypeClasses #-}+{-# LANGUAGE FunctionalDependencies #-}+{-# LANGUAGE UndecidableInstances #-}+{-# LANGUAGE FlexibleContexts #-}++-- | This module exposes the implementation details of+-- "Graphics.EasyRender". Most user code should not need to import+-- this; they should import "Graphics.EasyRender" instead. +-- +-- This module provides efficient functions for rendering vector+-- graphics to a number of formats, including EPS, PostScript, and+-- PDF. It provides an abstraction for multi-page documents, as well+-- as a set of graphics primitives for page descriptions. +-- +-- The graphics model is similar to that of the PostScript and PDF+-- languages, but we only implement a subset of their functionality.+-- Care has been taken that graphics rendering is done efficiently and+-- as lazily as possible; documents are rendered \"on the fly\",+-- without the need to store the whole document in memory.+-- +-- The provided document description model consists of two separate+-- layers of abstraction:+-- +-- * /drawing/ is concerned with placing marks on a fixed surface, and+-- takes place in the 'Draw' monad;+-- +-- * /document structure/ is concerned with a sequence of pages, their+-- bounding boxes, and other meta-data. It takes place in the+-- 'Document' monad.++module Graphics.EasyRender.Internal where++import Graphics.EasyRender.Auxiliary++import Codec.Compression.Zlib+import Control.Monad.State+import qualified Data.ByteString.Lazy as ByteString+import Data.Char+import Data.List+import qualified Data.Map as Map+import Data.Map (Map)+import System.IO+import Text.Printf++-- ----------------------------------------------------------------------+-- * Types++-- ----------------------------------------------------------------------+-- ** Coordinates++-- | The type of /x/-coordinates.+type X = Double++-- | The type of /y/-coordinates.+type Y = Double++-- ----------------------------------------------------------------------+-- ** Colors++-- | The type of colors.+data Color =+ Color_RGB Double Double Double -- ^ Red, green and blue components,+ -- in the range from 0.0 (dark) to+ -- 1.0 (bright).+ | Color_Gray Double -- ^ Gray value, in the range from+ -- 0.0 (black) to 1.0 (white).+ deriving (Show)++-- ----------------------------------------------------------------------+-- ** Fonts++-- | A enumeration type for base fonts. For the time being, we only+-- offer TimesRoman and Helvetica.+data Basefont = TimesRoman | Helvetica+ deriving (Show)++-- | A type representing font metrics for a given base font. The first+-- component is the default width of characters; the second component+-- is a map from characters to widths.+type Fontmetric = (Double, Map Char Double)++-- | Define a font metric for each base font.+metric :: Basefont -> Fontmetric+metric TimesRoman = metric_timesroman+metric Helvetica = metric_helvetica++-- | Font metrics for TimesRoman.+metric_timesroman :: Fontmetric+metric_timesroman = (0.5, m) where+ m = Map.fromList $ map (\(n,w) -> (chr n, w))+ [(32,0.25), (33,0.332031), (34,0.40625), (37,0.832031), (38,0.777344),+ (39,0.332031), (40,0.332031), (41,0.332031), (44,0.25), (45,0.332031),+ (46,0.25), (47,0.277344), (58,0.277344), (59,0.277344), (63,0.441406),+ (64,0.917969), (65,0.71875), (66,0.664062), (67,0.664062), (68,0.71875),+ (69,0.609375), (71,0.71875), (72,0.71875), (73,0.332031), (74,0.386719),+ (75,0.71875), (76,0.609375), (77,0.886719), (78,0.71875), (79,0.71875),+ (81,0.71875), (82,0.664062), (84,0.609375), (85,0.71875), (86,0.71875),+ (87,0.941406), (88,0.71875), (89,0.71875), (90,0.609375), (91,0.332031),+ (92,0.277344), (93,0.332031), (94,0.46875), (96,0.332031),+ (97,0.441406), (99,0.441406), (101,0.441406), (102,0.332031),+ (105,0.277344), (106,0.277344), (108,0.277344), (109,0.777344),+ (114,0.332031), (115,0.386719), (116,0.277344), (119,0.71875),+ (122,0.441406), (123,0.476562), (124,0.199219), (125,0.476562),+ (161,0.332031), (164,0.164062), (169,0.179688), (170,0.441406),+ (172,0.332031), (173,0.332031), (180,0.25), (182,0.449219),+ (183,0.347656), (184,0.332031), (185,0.441406), (186,0.441406),+ (188,1.0), (189,1.0), (191,0.441406), (193,0.332031), (194,0.332031),+ (195,0.332031), (196,0.332031), (197,0.332031), (198,0.332031),+ (199,0.332031), (200,0.332031), (202,0.332031), (203,0.332031),+ (205,0.332031), (206,0.332031), (207,0.332031), (208,1.0),+ (225,0.886719), (227,0.273438), (232,0.609375), (233,0.71875),+ (234,0.886719), (241,0.664062), (245,0.277344), (248,0.277344),+ (250,0.71875)]++-- | Font metrics for Helvetica.+metric_helvetica :: Fontmetric+metric_helvetica = (0.277344, m) where+ m = Map.fromList $ map (\(n,w) -> (chr n, w))+ [(34,0.351562), (35,0.554688), (36,0.554688), (37,0.886719),+ (38,0.664062), (39,0.21875), (40,0.332031), (41,0.332031), (42,0.386719),+ (43,0.582031), (45,0.332031), (48,0.554688), (49,0.554688),+ (50,0.554688), (51,0.554688), (52,0.554688), (53,0.554688),+ (54,0.554688), (55,0.554688), (56,0.554688), (57,0.554688),+ (60,0.582031), (61,0.582031), (62,0.582031), (63,0.554688), (64,1.01172),+ (65,0.664062), (66,0.664062), (67,0.71875), (68,0.71875), (69,0.664062),+ (70,0.609375), (71,0.777344), (72,0.71875), (74,0.5), (75,0.664062),+ (76,0.554688), (77,0.832031), (78,0.71875), (79,0.777344), (80,0.664062),+ (81,0.777344), (82,0.71875), (83,0.664062), (84,0.609375), (85,0.71875),+ (86,0.664062), (87,0.941406), (88,0.664062), (89,0.664062),+ (90,0.609375), (94,0.46875), (95,0.554688), (96,0.21875), (97,0.554688),+ (98,0.554688), (99,0.5), (100,0.554688), (101,0.554688), (103,0.554688),+ (104,0.554688), (105,0.21875), (106,0.21875), (107,0.5), (108,0.21875),+ (109,0.832031), (110,0.554688), (111,0.554688), (112,0.554688),+ (113,0.554688), (114,0.332031), (115,0.5), (117,0.554688), (118,0.5),+ (119,0.71875), (120,0.5), (121,0.5), (122,0.5), (123,0.332031),+ (124,0.257812), (125,0.332031), (126,0.582031), (161,0.332031),+ (162,0.554688), (163,0.554688), (164,0.164062), (165,0.554688),+ (166,0.554688), (167,0.554688), (168,0.554688), (169,0.1875),+ (170,0.332031), (171,0.554688), (172,0.332031), (173,0.332031),+ (174,0.5), (175,0.5), (177,0.554688), (178,0.554688), (179,0.554688),+ (182,0.535156), (183,0.347656), (184,0.21875), (185,0.332031),+ (186,0.332031), (187,0.554688), (188,1.0), (189,1.0), (191,0.609375),+ (193,0.332031), (194,0.332031), (195,0.332031), (196,0.332031),+ (197,0.332031), (198,0.332031), (199,0.332031), (200,0.332031),+ (202,0.332031), (203,0.332031), (205,0.332031), (206,0.332031),+ (207,0.332031), (208,1.0), (225,1.0), (227,0.367188), (232,0.554688),+ (233,0.777344), (234,1.0), (235,0.363281), (241,0.886719), (248,0.21875),+ (249,0.609375), (250,0.941406), (251,0.609375)]++-- | Look up the width of a character in the given metric.+char_metric :: Fontmetric -> Char -> Double+char_metric (d, m) c = case Map.lookup c m of+ Nothing -> d+ Just w -> w+ +-- | Look up with width of a string in the given metric.+string_metric :: Fontmetric -> String -> Double+string_metric metric s = sum [ char_metric metric c | c <- s ]++-- | A data type describing a scaled font. This consists of a base+-- font and a point size.+data Font = Font Basefont Double+ deriving (Show)++-- | Return the nominal point size of a font.+nominalsize :: Font -> Double+nominalsize (Font basefont pointsize) = pointsize++-- | Return the width of the given string in the given font.+text_width :: Font -> String -> Double+text_width (Font basefont pointsize) s = pointsize * string_metric m s+ where+ m = metric basefont++-- ----------------------------------------------------------------------+-- ** Alignment++-- | A real number representing text alignment. 0 = left aligned, 0.5+-- = centered, 1 = right aligned. Intermediate values are also+-- possible. For example, an alignment value of 0.25 means one quarter+-- of the way between left aligned and right aligned.+type Alignment = Double++-- | Left alignment.+align_left :: Alignment+align_left = 0.0++-- | Centered alignment.+align_center :: Alignment+align_center = 0.5++-- | Right alignment.+align_right :: Alignment+align_right = 1.0++-- ----------------------------------------------------------------------+-- * The Document monad+ +-- $DOCUMENTMODEL +-- +-- Document description takes place in the 'Document' monad. A basic+-- multi-page document has the following structure:+-- +-- > document :: Document ()+-- > document = do+-- > newpage x y $ do+-- > <<<drawing commands>>>+-- > newpage x y $ do+-- > <<<drawing commands>>>+-- > ...+-- +-- Here, each 'newpage' command describes one page of the+-- document. The parameters /x/ and /y/ specify the dimensions of the+-- page bounding box. They are expressed in units of PostScript+-- points, i.e., multiples of 1/72 inch.+-- +-- Sometimes the bounding box for a page is not known until after the+-- page content has been generated. For this purpose, we also provide+-- the following alternative to the 'newpage' command:+-- +-- > newpage_defer $ do+-- > <<<drawing commands>>>+-- > endpage x y+-- +-- It works just like the 'newpage' command, except that the bounding+-- box is given at the end.++-- | The Document monad.+data Document a =+ Document_Return a -- ^ Terminate with a result.+ | Document_Page X Y (Draw (Document a)) -- ^ Page with bounding box+ -- known at the beginning.+ | Document_Page_defer (Draw (X, Y, Document a)) + -- ^ Page with bounding box+ -- known at the end.++instance Monad Document where+ return a = Document_Return a+ f >>= g = case f of+ Document_Return a -> g a+ Document_Page x y draw -> Document_Page x y draw' where+ draw' = do+ f' <- draw+ return (f' >>= g)+ Document_Page_defer draw -> Document_Page_defer draw' where+ draw' = do+ (x, y, f') <- draw+ return (x, y, f' >>= g)+ +-- ----------------------------------------------------------------------+-- ** A vacuous run function+ +-- | Skip document without rendering. +document_skip :: Document a -> a+document_skip (Document_Return a) = a+document_skip (Document_Page x y draw) = document_skip a where+ a = draw_skip draw+document_skip (Document_Page_defer draw) = document_skip a where+ (x, y, a) = draw_skip draw++-- ----------------------------------------------------------------------+-- ** User-level document structuring commands++-- | Create a page of the given bounding box, containing the given+-- drawing.+newpage :: X -> Y -> Draw a -> Document a+newpage x y draw =+ Document_Page x y draw' where+ draw' = do+ a <- draw+ return (Document_Return a)+ +-- | Create a page containing the given drawing, with the bounding box+-- computed at the end of the drawing routines.+newpage_defer :: Draw (X, Y, a) -> Document a+newpage_defer draw =+ Document_Page_defer draw' where+ draw' = do+ (x, y, a) <- draw+ return (x, y, Document_Return a)++-- | End the page with the given bounding box.+endpage :: X -> Y -> Draw (X, Y, ())+endpage x y = do+ return (x, y, ())++-- ----------------------------------------------------------------------+-- * The Draw monad++-- $DRAWINGMODEL +-- +-- The description of the visible content of a page take place in the+-- 'Draw' monad. It takes the form of a sequence of drawing commands,+-- for example:+-- +-- > moveto 10 10+-- > lineto 10 100+-- > lineto 100 100+-- > lineto 100 10+-- > closepath+-- > stroke+-- +-- The graphics model is similar to that of the PostScript and PDF+-- languages. The basic concept is that of a /path/, which is a+-- sequence of straight and curved line segments. Paths are first+-- constructed using /path construction commands/, and then painted+-- using /painting commands/, depending on a set of current +-- /graphics parameters/ and a current /coordinate system/.+-- +-- We also provide block structure. Changes to the graphics state+-- (color, coordinate system, etc.) that are done within a block are+-- local to the block.+-- +-- > block $ do+-- > <<drawing commands>>+ +-- ----------------------------------------------------------------------+-- ** Internal definition of the Draw monad++-- | An abstract data type describing individual drawing commands.+data DrawCommand =+ Newpath -- ^ Set the current path to empty.+ | Moveto X Y -- ^ Start a new subpath at the given coordinates.+ | Lineto X Y -- ^ Append a straight line to the current subpath.+ | Curveto X Y X Y X Y -- ^ Append a Bezier curve segment.+ | Closepath -- ^ Close the current subpath.+ | Stroke -- ^ Stroke and clear the current path.+ | Fill Color -- ^ Fill and clear the current path.+ | FillStroke Color -- ^ Fill and stroke and clear the current path.+ | TextBox Alignment Font Color X Y X Y Double String -- ^ Text.+ | SetLineWidth Double -- ^ Set current line width.+ | SetColor Color -- ^ Set current color.+ | Translate X Y -- ^ Translate current coordinate system.+ | Scale X Y -- ^ Scale the current coordinate system.+ | Rotate Double -- ^ Rotate the current coordinate system.+ | Comment String -- ^ A human-readable comment, not rendered+ | Subroutine (Draw ()) [CustomDef]+ -- ^ A subroutine is a composite drawing command. In+ -- addition to a default definition that works for+ -- any backend, it can also have optional specialized+ -- definitions for particular backends.+ deriving (Show)++-- $ In understanding how the 'Draw' monad works, it is useful to keep+-- in mind that there is an isomorphism+-- +-- @Draw /a/@ ≅ @Draw ()@ ×. /a/,+-- +-- where \"×.\" is left-strict product, i.e., if the left-hand-side is+-- undefined, then so is the entire expression.++-- | The Draw monad.+data Draw a = + Draw_Return a -- ^ Terminate with a result.+ | Draw_Write DrawCommand (Draw a) -- ^ Write a command and continue.+ | Draw_Block (Draw (Draw a)) -- ^ Block structure. Perform the+ -- commands of the outer 'Draw' in+ -- a temporary copy of the+ -- graphics state, then continue+ -- with the inner 'Draw' in the+ -- original graphics state.+ deriving (Show)+ +instance Monad Draw where+ return a = Draw_Return a+ f >>= g = case f of+ Draw_Return a -> g a+ Draw_Write cmd f' -> Draw_Write cmd (f' >>= g)+ Draw_Block draw -> Draw_Block draw' where+ draw' = do+ f' <- draw+ return (f' >>= g)++-- ----------------------------------------------------------------------+-- ** Low-level operations for the Draw monad++-- | Write the given command to the 'Draw' monad.+draw_write :: DrawCommand -> Draw ()+draw_write cmd = + Draw_Write cmd (Draw_Return ()) ++-- | Create a new subroutine.+draw_subroutine :: [CustomDef] -> Draw () -> Draw ()+draw_subroutine alt draw =+ draw_write (Subroutine draw alt)++-- | Write a block to the 'Draw' monad.+draw_block :: Draw a -> Draw a+draw_block draw = + Draw_Block draw' where+ draw' = do+ a <- draw+ return (Draw_Return a)+ +-- ----------------------------------------------------------------------+-- ** A vacuous run function++-- | Skip draw actions without rendering.+draw_skip :: Draw a -> a+draw_skip (Draw_Return x) = x+draw_skip (Draw_Write cmd cont) = draw_skip cont+draw_skip (Draw_Block f) = draw_skip (draw_skip f)++-- ----------------------------------------------------------------------+-- ** User-level drawing commands++-- ----------------------------------------------------------------------+-- *** Path construction commands++-- $PATHCONSTRUCTION+-- +-- During path construction, there is a notion of /current path/ and+-- /current point/. A path may consist of zero or more connected+-- subpaths, and each subpath is either open or closed. ++-- | Set the current path to empty.+newpath :: Draw ()+newpath = draw_write (Newpath)++-- | Start a new subpath at (/x/,/y/). The point (/x/,/y/) becomes the+-- current point.+moveto :: X -> Y -> Draw ()+moveto x y = draw_write (Moveto x y)++-- | Extend the current subpath by a straight line segment from the+-- current point to (/x/,/y/). The point (/x/,/y/) becomes the current+-- point.+lineto :: X -> Y -> Draw ()+lineto x y = draw_write (Lineto x y)++-- | @'curveto' /x1/ /y1/ /x2/ /y2/ /x/ /y/@: Extend the current+-- subpath by a Bezier curve segment from the current point to+-- (/x/,/y/), with control points (/x1/,/y1/) and (/x2/,/y2/). The+-- point (/x/,/y/) becomes the current point.+curveto :: X -> Y -> X -> Y -> X -> Y -> Draw ()+curveto x1 y1 x2 y2 x y = draw_write (Curveto x1 y1 x2 y2 x y)++-- | Close the current subpath. If necessary, connect the subpath's+-- final and initial points by a straight line segment. Note that a+-- closed path is rendered differently than a non-closed path whose+-- initial and final points coincide, because in the latter case, the+-- endpoints are capped rather than mitered.+closepath :: Draw ()+closepath = draw_write (Closepath)++-- ----------------------------------------------------------------------+-- *** Painting commands++-- | Stroke the current path, using the current line color, line+-- width, and other graphics parameters. This operation implicitly+-- resets the current path to empty.+stroke :: Draw ()+stroke = draw_write (Stroke)++-- | Fill the current path, using the given color. This operation+-- implicitly resets the current path to empty. +fill :: Color -> Draw ()+fill color = draw_write (Fill color)++-- | Fill the current path, using the given color; also stroke the+-- path using the current line color. This operation implicitly resets+-- the current path to empty.+fillstroke :: Color -> Draw ()+fillstroke color = draw_write (FillStroke color)++-- ----------------------------------------------------------------------+-- *** Text++-- | @'textbox' /a/ /f/ /c/ /x0/ /y0/ /x1/ /y1/ /b/ /s/@: Write the+-- given string on an imaginary line from point (/x0/,/y0/) to+-- (/x1/,/y1/), using font /f/ and color /c/. If the text is too wide+-- to fit on the line, it is scaled down. Otherwise, it is aligned+-- according to the alignment parameter /a/. The parameter /b/+-- specifies an additional offset by which to lower the text, with+-- respect to the text's nominal size. For example, if /b/=0, then the+-- above-mentioned imaginary line from (/x0/,/y0/) to (/x1/,/y1/)+-- coincides with the text's usual baseline. If /b/=0.5, then this+-- line approximately goes through the center of each character.+-- +-- \[image textbox.png]+textbox :: Alignment -> Font -> Color -> X -> Y -> X -> Y -> Double -> String -> Draw ()+textbox a f c x0 y0 x1 y1 b s = draw_write (TextBox a f c x0 y0 x1 y1 b s)++-- ----------------------------------------------------------------------+-- *** Graphics parameters++-- $GRAPHICSPARAMETERS+-- +-- The painting commands rely on a set of graphics parameters. The+-- graphics parameters are initially set to default values, and can be+-- altered with the following commands.++-- | Set the line width. The initial line width is 1.+setlinewidth :: Double -> Draw ()+setlinewidth x = draw_write (SetLineWidth x)++-- | Set the current color for stroking. The initial stroke color is+-- black.+setcolor :: Color -> Draw ()+setcolor color = draw_write (SetColor color)++-- ----------------------------------------------------------------------+-- *** Coordinate system++-- $COORDINATESYSTEM+-- +-- Coordinates, lengths, widths, etc, are all interpreted relative to+-- a /current coordinate system/. The initial coordinate system of+-- each page has the origin in the lower left corner, with each unit+-- equaling one PostScript point (1/72 inch). The following commands+-- can be used to change the current coordinate system.++-- | Translate the current coordinate system by (/x/,/y/).+translate :: X -> Y -> Draw ()+translate x y = draw_write (Translate x y)++-- | Scale the current coordinate system by (/s/,/t/). Here, /s/ is+-- the scaling factor in the /x/-direction, and /t/ is the scaling+-- factor in the /y/-direction.+scale :: X -> Y -> Draw ()+scale x y = draw_write (Scale x y)++-- | Rotate the current coordinate system by /angle/, measured+-- counterclockwise in degrees.+rotate :: Double -> Draw ()+rotate angle = draw_write (Rotate angle)++-- ----------------------------------------------------------------------+-- *** Comments++-- | Insert a human-readable comment in the content stream. This is+-- for information only, and is not rendered in the graphical output.+comment :: String -> Draw ()+comment s = draw_write (Comment s)++-- ----------------------------------------------------------------------+-- *** Block structure++-- $BLOCKSTRUCTURE +-- +-- Drawing operations can be grouped into blocks with the 'block'+-- operator. Changes to the graphics parameters and coordinate system+-- are local to the block. It is undefined whether changes to the+-- current path made within a block persist after the end of the block+-- (they do in PDF, but not in PostScript). Therefore, path+-- construction should not be broken up across end-of-block boundaries.++-- | Perform a block of commands in a local copy of the graphics+-- state. This is intended to be used like this:+-- +-- > block $ do+-- > <<drawing commands>>+block :: Draw a -> Draw a+block = draw_block++-- ----------------------------------------------------------------------+-- *** Derived commands++-- $ PDF has no built-in command for drawing circular arcs, so we+-- define it here. Since PostScript does have such a command, we use+-- the 'draw_subroutine' mechanism.++-- | Start a new subpath consisting of a circular arc segment. The+-- arc segment is centered at (/x/,/y/), has radius /r/, and extends+-- from angle /a1/ to angle /a2/, measured in degrees,+-- counterclockwise from the /x/-axis. The arc is drawn clockwise if+-- /a2/ ≥ /a1/, and counterclockwise otherwise. The final point+-- becomes the new current point.+arc :: X -> Y -> Double -> Double -> Double -> Draw ()+arc x y r a1 a2 = draw_subroutine alt $ do+ arc_internal False x y r r a1 a2+ where+ alt = [custom_ps $ printf "%f %f moveto\n" x0 y0 ++ printf "%f %f %f %f %f %s\n" x y r a1 a2 (if a1 <= a2 then "arc" else "arcn"),+ custom_ascii $ printf "Arc %f %f %f %f %f\n" x y r a1 a2]+ x0 = x + r * cos (pi/180 * a1)+ y0 = y + r * sin (pi/180 * a1)++-- | Like 'arc', except append to the current subpath. If necessary,+-- add a straight line segment from the current point to the starting+-- point of the arc.+arc_append :: X -> Y -> Double -> Double -> Double -> Draw ()+arc_append x y r a1 a2 = draw_subroutine alt $ do+ arc_internal True x y r r a1 a2+ where+ alt = [custom_ps $ printf "%f %f %f %f %f %s\n" x y r a1 a2 (if a1 <= a2 then "arc" else "arcn"),+ custom_ascii $ printf "Arc_append %f %f %f %f %f\n" x y r a1 a2]++-- | Append a new closed subpath consisting of an oval centered at+-- (/x/,/y/), with horizontal and vertical radii /rx/ and /ry/,+-- respectively.+oval :: X -> Y -> X -> Y -> Draw ()+oval x y rx ry = do+ arc_internal False x y rx ry 0 360+ closepath++-- | The common implementation of 'arc', 'arc_append', and 'oval'. The+-- first parameter is a boolean flag indicating whether to append to+-- an existing subpath or start a new subpath. The fourth and fifth+-- parameter are the horizontal and vertical radius.+arc_internal :: Bool -> X -> Y -> Double -> Double -> Double -> Double -> Draw ()+arc_internal connect x y rx ry a1 a2 = do+ if connect then lineto x0 y0 else moveto x0 y0+ -- We divide the arc into n segments of 90 degrees or less.+ sequence_ [ aux a | i <- [0..n-1], let a = a1 + (fromIntegral i)*phi ]+ where+ (x0, y0) = point rx ry a1+ n = int_ceiling (abs(a2 - a1) / 90)+ phi = if n > 0 then (a2 - a1) / (fromIntegral n) else 0+ alpha = 4/3 * c / (1+c)+ c = cos' (phi/2)+ point rx ry a = (x + rx * cos' a, y + ry * sin' a)+ cos' x = cos (pi/180 * x)+ sin' x = sin (pi/180 * x)+ along (x0,y0) (x1,y1) alpha = (x0 + alpha * (x1-x0), y0 + alpha * (y1-y0))+ aux a = curveto x1 y1 x2 y2 x3 y3+ where+ (x0, y0) = point rx ry a+ (x3, y3) = point rx ry (a + phi)+ (xp, yp) = point (rx/c) (ry/c) (a + phi/2)+ (x1, y1) = along (x0, y0) (xp, yp) alpha+ (x2, y2) = along (x3, y3) (xp, yp) alpha++-- | @'rectangle' /x/ /y/ /w/ /h/@: Draw a rectangle of width /w/ and+-- height /h/, starting from (/x/,/y/). If /w/ and /h/ are positive,+-- then (/x/,/y/) is the lower left corner.+rectangle :: X -> Y -> X -> Y -> Draw ()+rectangle x y w h = draw_subroutine alt def where+ def = do+ moveto x y+ lineto x (y+h)+ lineto (x+w) (y+h)+ lineto (x+w) y+ closepath+ alt = [+ custom_pdf $ printf "%f %f %f %f re\n" x y w h,+ custom_ascii $ printf "Rectangle %f %f %f %f\n" x y w h+ ]++-- ----------------------------------------------------------------------+-- * Customization++-- $CUSTOMIZATION+-- +-- The document and drawing abstractions provided by this module are+-- purposely kept general-purpose, and do not include+-- application-specific features. However, we provide a mechanism by+-- which applications can provide customized drawing commands and+-- other custom features.++-- ** Custom drawing commands++-- $CUSTOMCOMMANDS+-- +-- It is sometimes useful to use customized drawing commands. For+-- example, an application that draws many rectangles might like to+-- define a custom 'rectangle' function for appending a rectangle to+-- the current path. Of course this can be defined as an ordinary+-- Haskell function, using elementary drawing commands:+-- +-- > my_rect :: X -> Y -> X -> Y -> Draw ()+-- > my_rect x0 y0 x1 y1 = do+-- > moveto x0 y0+-- > lineto x0 y1+-- > lineto x1 y1+-- > lineto x1 y0+-- > closepath+-- +-- However, sometimes it is nice to make use of specialized abilities+-- of individual backends. For example, PDF already has a built-in+-- rectangle drawing command, and PostScript has the ability to define+-- custom subroutines within the document text. Using these features+-- can decrease the size of the generated documents. +-- +-- We therefore provide a facility for defining new drawing commands+-- with backend-specific implementations. For example, a more general+-- version of the above 'my_rect' function can be defined as+-- follows:+-- +-- > my_rect :: X -> Y -> X -> Y -> Draw ()+-- > my_rect x0 y0 x1 y1 = draw_subroutine alt $ do+-- > moveto x0 y0+-- > lineto x0 y1+-- > lineto x1 y1+-- > lineto x1 y0+-- > closepath+-- > where+-- > alt = [+-- > custom_ps $ printf "%f %f %f %f rect\n" x0 y0 x1 y1,+-- > custom_pdf $ printf "%f %f %f %f re\n" x0 y0 (x1-x0) (y1-y0),+-- > custom_ascii $ printf "My_rect %f %f %f %f\n" x0 y0 x1 y1+-- > ]+-- +-- The idea is to provide a default definition in terms of primitive+-- drawing commands, as well as a list of various backend specific+-- definitions. In the case of PostScript subroutines, the PostScript+-- file must then also be supplied with a definition for the /rect/+-- subroutine, which can be done with the command 'render_ps_custom':+-- +-- > my_ps_defs = "/rect { ... } bind def\n"+-- >+-- > my_render_ps = render_ps_custom custom { ps_defs = my_ps_defs }+-- +-- Note that the 'draw_subroutine' customization mechanism is entirely+-- optional. Its purpose is to generate shorter output for some+-- backends; if it is omitted, the file may be be longer but should+-- look the same.++-- | An enumeration of backend languages, for the purpose of defining+-- custom drawing commands. Note that several backends (e.g. EPS and+-- PostScript) may share the same language, and therefore they are+-- only represented once in this enumeration.+data Language =+ Language_PS -- ^ PostScript (including EPS)+ | Language_PDF -- ^ PDF+ | Language_ASCII -- ^ ASCII (for debugging)+ deriving (Show, Eq, Ord)++-- | The type of custom definitions, to be used with the+-- 'draw_subroutine' command.+data CustomDef = CustomDef Language String+ deriving (Show)++-- | Define a custom PostScript definition.+custom_ps :: String -> CustomDef+custom_ps s = CustomDef Language_PS s++-- | Define a custom PDF definition.+custom_pdf :: String -> CustomDef+custom_pdf s = CustomDef Language_PDF s++-- | Define a custom ASCII definition.+custom_ascii :: String -> CustomDef+custom_ascii s = CustomDef Language_ASCII s++-- | Look up an element in a list of 'CustomDef's.+custom_lookup :: Language -> [CustomDef] -> Maybe String+custom_lookup lang defs = + case find (\(CustomDef l _) -> l==lang) defs of+ Nothing -> Nothing+ Just (CustomDef l s) -> Just s++-- ----------------------------------------------------------------------+-- ** Customization interface++-- | A data structure that holds application-specific meta-data and+-- customization information.+data Custom = Custom { + creator :: String, -- ^ Name of the software that created the file.+ -- Example: \"MyApp 1.0\". Note: this is intended+ -- to hold the name of the software, not the+ -- human user, that created the document.+ ps_defs :: String -- ^ Definitions to go in the PostScript+ -- preamble.+ }+ +-- | An empty customization structure. Customizations should be+-- specified by modifying 'custom', for example:+-- +-- > custom { creator = "MyApp 1.0" }+custom :: Custom+custom = Custom {+ creator = "",+ ps_defs = ""+ }++-- ----------------------------------------------------------------------+-- * Generic string output++-- ----------------------------------------------------------------------+-- ** The WriterMonad class++-- | A 'WriterMonad' is any monad that one can output strings to.+-- +-- Minimal complete definition: 'wPutChar' or 'wPutStr'.+class Monad m => WriterMonad m where+ -- | Write a character.+ wPutChar :: Char -> m ()+ wPutChar c = wPutStr [c]+ + -- | Write a string.+ wPutStr :: String -> m ()+ wPutStr s = sequence_ [ wPutChar c | c <- s ]+ +-- | Like 'wPutStr', but adds a newline character.+wPutStrLn :: (WriterMonad m) => String -> m ()+wPutStrLn s = do+ wPutStr s+ wPutChar '\n'+ +-- | Write a value of any printable type, and add a newline.+wprint :: (WriterMonad m, Show a) => a -> m ()+wprint x = wPutStrLn (show x)+ +instance WriterMonad IO where+ wPutChar = putChar+ wPutStr = putStr++-- ----------------------------------------------------------------------+-- ** The Writer monad++-- | A generic 'WriterMonad'.+data Writer a =+ Writer_Return a -- ^ Terminate with a result.+ | Writer_PutChar Char (Writer a) -- ^ Write a character.+ | Writer_PutStr String (Writer a) -- ^ Write a string.++instance Monad Writer where+ return a = Writer_Return a+ f >>= g = case f of+ Writer_Return a -> g a+ Writer_PutChar c f' -> Writer_PutChar c (f' >>= g)+ Writer_PutStr s f' -> Writer_PutStr s (f' >>= g) + +instance WriterMonad Writer where+ wPutChar c = Writer_PutChar c (Writer_Return ())+ wPutStr s = Writer_PutStr s (Writer_Return ())+ +-- ----------------------------------------------------------------------+-- ** Isomorphism with (String, a)+ +-- | Isomorphically map a 'Writer' computation to a pair of a string+-- and a value.+-- +-- Important usage note: the 'String' in the output is produced+-- lazily, and before /a/ is produced. To preserve laziness, do not+-- evaluate /a/ before the end of 'String' has been reached.+writer_to_pair :: Writer a -> (String, a)+writer_to_pair (Writer_Return a) = ("", a)+writer_to_pair (Writer_PutChar c cont) = (c:t, a) where+ (t, a) = writer_to_pair cont+writer_to_pair (Writer_PutStr s cont) = (s ++ t, a) where+ (t, a) = writer_to_pair cont++-- | The inverse of 'writer_to_pair'.+pair_to_writer :: (String, a) -> Writer a+pair_to_writer (s, a) = do+ wPutStr s+ return a++-- ----------------------------------------------------------------------+-- ** Run functions++-- | Run a 'Writer' computation in any 'WriterMonad'.+run_writer :: (WriterMonad m) => Writer a -> m a+run_writer (Writer_Return a) = return a+run_writer (Writer_PutChar c cont) = do+ wPutChar c+ run_writer cont+run_writer (Writer_PutStr s cont) = do+ wPutStr s+ run_writer cont++-- | Run a writer in the 'IO' monad by printing to a file.+writer_to_file :: Handle -> Writer a -> IO a+writer_to_file h (Writer_Return a) = return a+writer_to_file h (Writer_PutChar c cont) = do+ hPutChar h c+ writer_to_file h cont+writer_to_file h (Writer_PutStr s cont) = do+ hPutStr h s+ writer_to_file h cont++-- | Run a writer by printing to a string.+writer_to_string :: Writer a -> String+writer_to_string = fst . writer_to_pair++-- ----------------------------------------------------------------------+-- ** Boxed monads++-- | Create an identical \"boxed\" copy of a type constructor. This is+-- used for technical reasons, to allow the 'wprintf' operation to be+-- typed.+newtype Boxed m a = Boxed (m a)++-- | Unbox a boxed item.+unbox :: Boxed m a -> m a+unbox (Boxed x) = x++instance Monad m => Monad (Boxed m) where+ return a = Boxed (return a)+ f >>= g = Boxed (unbox f >>= (unbox . g))++instance WriterMonad m => WriterMonad (Boxed m) where+ wPutChar c = Boxed (wPutChar c)+ wPutStr c = Boxed (wPutStr c)++instance MonadState s m => MonadState s (Boxed m) where+ get = Boxed get+ put s = Boxed (put s)++-- ----------------------------------------------------------------------+-- ** Currying in a boxed monad+ +-- | A class to curry/uncurry functions in any boxed monad. This+-- establishes an isomorphism+-- +-- > @fun ≅ args -> Boxed m res,@+-- +-- where+-- +-- > fun = a1 -> a2 -> ... -> an -> Boxed m res,+-- > args = (a1, (a2, (..., (an, ())))).+class Boxed_Curry fun args m res | fun -> args res m, args res m -> fun where+ boxed_curry :: (args -> Boxed m res) -> fun+ boxed_uncurry :: fun -> (args -> Boxed m res)++instance Boxed_Curry (Boxed m a) () m a where+ boxed_curry g = g ()+ boxed_uncurry x = const x+ +instance Boxed_Curry fun args m res => Boxed_Curry (a -> fun) (a, args) m res where+ boxed_curry g x = boxed_curry (\xs -> g (x,xs))+ boxed_uncurry f (x,xs) = boxed_uncurry (f x) xs++-- ---------------------------------------------------------------------- +-- ** Formatted printing+ +-- | Print a formatted value in the context of a boxed WriterMonad. Usage:+-- +-- wprintf "%f %f" x y :: Boxed Writer+wprintf :: (Boxed_Curry fun args m (), WriterMonad m, Curry fun' args String, PrintfType fun') => String -> fun+wprintf fmt = g where+ g = boxed_curry g'+ g' args = wPutStr (f' args)+ f' = muncurry f+ f = printf fmt++-- | In any 'WriterMonad', introduce a block in which 'wprintf' can be+-- used. This has no computational overhead, i.e., is compiled to the+-- identity operation; it exists only to please the type system,+-- due to the fancy typing of 'wprintf'.+with_printf :: (WriterMonad m) => Boxed m a -> m a+with_printf = unbox++-- ----------------------------------------------------------------------+-- ** Filters++-- $ A filter is any function from strings to strings, but it should+-- usually be lazy. Typical examples are compression, encryption,+-- ASCII armoring, character encoding, and their inverses.+-- +-- We provide a convenient operator for temporarily wrapping a filter+-- around the 'Writer' monad, as well as specific filters.++-- | Wrap a filter around a 'Writer' computation. This introduces a+-- local block within the 'Writer' monad; all text written within the+-- block is encoded through the given filter. Filters can be composed+-- and nested.+with_filter :: (WriterMonad m) => (String -> String) -> Writer a -> m a+with_filter encoding = run_writer . pair_to_writer . (\(x,y) -> (encoding x, y)) . writer_to_pair++-- | A filter for performing \"flate\" (also known as \"zlib\")+-- compression. +-- +-- Note: both the input and output strings are regarded as sequences+-- of bytes, not characters. Any characters outside the byte range are+-- truncated to 8 bits.+flate_filter :: String -> String+flate_filter = map chr . map fromIntegral . ByteString.unpack . compress . ByteString.pack . map fromIntegral . map ord++-- ----------------------------------------------------------------------+-- * Backends++-- ----------------------------------------------------------------------+-- ** Auxiliary functions++-- | Ensure that the last line of the string ends in a newline+-- character, adding one if necessary. An empty string is considered to contain zero lines, so no newline character needs to be added. +ensure_nl :: String -> String+ensure_nl "" = ""+ensure_nl s = + if last s == '\n' then s else s++"\n"++-- ----------------------------------------------------------------------+-- * ASCII output++-- | Render draw actions as ASCII.+draw_to_ascii :: Draw a -> Writer a+draw_to_ascii (Draw_Return x) = return x+draw_to_ascii (Draw_Write cmd cont) = do+ command_to_ascii cmd+ draw_to_ascii cont+draw_to_ascii (Draw_Block f) = do+ wPutStrLn "begin"+ cont <- draw_to_ascii f+ wPutStrLn "end"+ draw_to_ascii cont+ +-- | Render drawing commands as ASCII.+command_to_ascii :: DrawCommand -> Writer ()+command_to_ascii (Subroutine draw alt) =+ case custom_lookup Language_ASCII alt of+ Just out -> wPutStr (ensure_nl out)+ Nothing -> draw_to_ascii draw+command_to_ascii cmd =+ wprint cmd++-- | Render a document as ASCII.+document_to_ascii :: Document a -> Writer a+document_to_ascii (Document_Return x) = return x+document_to_ascii (Document_Page x y draw) = do+ wPutStrLn $ "startpage " ++ show x ++ " " ++ show y+ cont <- draw_to_ascii draw+ wPutStrLn "endpage"+ document_to_ascii cont+document_to_ascii (Document_Page_defer draw) = do+ wPutStrLn "startpage (atend)"+ (x, y, cont) <- draw_to_ascii draw+ wPutStrLn $ "endpage " ++ show x ++ " " ++ show y+ document_to_ascii cont+ +-- | Render a document as ASCII. This is for debugging purposes only.+-- The output is a sequence of drawing commands, rather than a+-- graphical representation.+render_ascii :: Document a -> Writer a+render_ascii = document_to_ascii++-- ----------------------------------------------------------------------+-- * PostScript output+ +-- ----------------------------------------------------------------------+-- ** Auxiliary functions++-- | Escape special characters in a string literal.+ps_escape :: String -> String+ps_escape [] = []+ps_escape ('\\' : t) = '\\' : '\\' : ps_escape t+ps_escape ('(' : t) = '\\' : '(' : ps_escape t+ps_escape (')' : t) = '\\' : ')' : ps_escape t+ps_escape (h : t) = h : ps_escape t++-- | Remove newline characters in a string.+remove_nl :: String -> String+remove_nl = map f where+ f '\n' = ' '+ f '\r' = ' '+ f x = x++-- ----------------------------------------------------------------------+-- ** The PSWriter monad++-- $ For convenience, we wrap the 'Writer' monad in a custom state monad;+-- the latter keeps track of the current document bounding box (i.e.,+-- the smallest bounding box containing all pages) and the current+-- number of pages.++-- | The type of page numbers.+type Page = Integer++-- | A state to keep track of a current bounding box and page number.+data PS_State = PS_State !X !Y !Page++-- | The initial 'PS_State'.+ps_state_empty :: PS_State+ps_state_empty = PS_State 0 0 0 ++-- | The 'PSWriter' monad. This is just a 'PS_State' wrapped around+-- the 'Writer' monad.+type PSWriter = Boxed (StateT PS_State Writer)++instance WriterMonad (StateT PS_State Writer) where+ wPutChar c = lift (wPutChar c)+ wPutStr s = lift (wPutStr s)++-- | Run function for the 'PSWriter' monad.+pswriter_run :: PSWriter a -> Writer a+pswriter_run f = evalStateT (unbox f) ps_state_empty++-- ----------------------------------------------------------------------+-- *** Access functions for the PSWriter monad++-- | Get the bounding box.+ps_get_bbox :: PSWriter (X, Y)+ps_get_bbox = do+ PS_State x y _ <- get+ return (x, y)+ +-- | Add to the bounding box.+ps_add_bbox :: X -> Y -> PSWriter ()+ps_add_bbox x y = do+ PS_State x' y' p <- get+ put (PS_State (x `max` x') (y `max` y') p)++-- | Get the page count.+ps_get_pagecount :: PSWriter Page+ps_get_pagecount = do+ PS_State _ _ p <- get+ return p+ +-- | Return the next page number.+ps_next_page :: PSWriter Page+ps_next_page = do+ PS_State x y p <- get+ put (PS_State x y (p+1))+ return (p+1)++-- ----------------------------------------------------------------------+-- ** Internal rendering to the PSWriter monad++-- | Render draw actions as PostScript.+draw_to_ps :: Draw a -> PSWriter a+draw_to_ps (Draw_Return x) = return x+draw_to_ps (Draw_Write cmd cont) = do+ command_to_ps cmd+ draw_to_ps cont+draw_to_ps (Draw_Block body) = do+ wPutStrLn "gsave"+ cont <- draw_to_ps body+ wPutStrLn "grestore"+ draw_to_ps cont+ +-- | Set the color.+color_to_ps :: Color -> PSWriter ()+color_to_ps (Color_RGB r g b) = do+ wprintf "%f %f %f setrgbcolor\n" r g b+color_to_ps (Color_Gray v) = do+ wprintf "%f setgray\n" v++-- | Set the font.+font_to_ps :: Font -> PSWriter ()+font_to_ps (Font TimesRoman pt) = do+ wprintf "/Times-Roman findfont %f scalefont setfont\n" pt+font_to_ps (Font Helvetica pt) = do+ wprintf "/Helvetica findfont %f scalefont setfont\n" pt++-- | Draw a single drawing command to PostScript.+command_to_ps :: DrawCommand -> PSWriter ()+command_to_ps (Newpath) = do+ wPutStrLn "newpath"+command_to_ps (Moveto x y) = do+ wprintf "%f %f moveto\n" x y+command_to_ps (Lineto x y) = do+ wprintf "%f %f lineto\n" x y+command_to_ps (Curveto x1 y1 x2 y2 x y) = do+ wprintf "%f %f %f %f %f %f curveto\n" x1 y1 x2 y2 x y+command_to_ps (Closepath) = do+ wPutStrLn "closepath"+command_to_ps (Stroke) = do+ wPutStrLn "stroke"+command_to_ps (Fill color) = do+ wPutStrLn "gsave" + color_to_ps color+ wPutStrLn "fill" + wPutStrLn "grestore"+ wPutStrLn "newpath"+command_to_ps (FillStroke color) = do+ wPutStrLn "gsave"+ color_to_ps color+ wPutStrLn "fill"+ wPutStrLn "grestore"+ wPutStrLn "stroke"+command_to_ps (TextBox align font color x0 y0 x1 y1 b s) = do+ wPutStrLn "gsave"+ font_to_ps font+ color_to_ps color+ wprintf "(%s) %f %f %f %f %f %f textbox\n" (ps_escape s) x0 y0 x1 y1 align yshift+ wPutStrLn "grestore"+ where+ yshift = -b * nominalsize font+command_to_ps (SetLineWidth x) = do+ wprintf "%f setlinewidth\n" x+command_to_ps (SetColor color) = do+ color_to_ps color+command_to_ps (Translate x y) = do+ wprintf "%f %f translate\n" x y+command_to_ps (Scale x y) = do+ wprintf "%f %f scale\n" x y+command_to_ps (Rotate angle) = do+ wprintf "%f rotate\n" angle+command_to_ps (Comment s) = do+ wprintf "%% %s\n" (remove_nl s)+command_to_ps (Subroutine draw alt) = + case custom_lookup Language_PS alt of+ Just out -> wprintf "%s" (ensure_nl out)+ Nothing -> draw_to_ps draw++-- | Render a document as PostScript.+document_to_ps :: Custom -> Document a -> PSWriter a+document_to_ps custom document = do+ -- global header+ wPutStrLn "%!PS-Adobe-3.0"+ wPutStrLn "%%LanguageLevel: 2"+ when (creator custom /= "") $ do+ wprintf "%%%%Creator: %s\n" (creator custom)+ wPutStrLn "%%BoundingBox: (atend)"+ wPutStrLn "%%HiResBoundingBox: (atend)"+ wPutStrLn "%%Pages: (atend)"+ wPutStrLn "%%EndComments"+ wPutStrLn "%%BeginSetup"+ wprintf "%s" global_ps_defs+ when (ps_defs custom /= "") $ do+ wprintf "%s" (ensure_nl $ ps_defs custom)+ wPutStrLn "%%EndSetup"+ a <- pages_to_ps document+ (x, y) <- ps_get_bbox+ pagecount <- ps_get_pagecount+ wPutStrLn "%%Trailer"+ wprintf "%%%%BoundingBox: 0 0 %d %d\n" (int_ceiling x) (int_ceiling y)+ wprintf "%%%%HiResBoundingBox: 0 0 %f %f\n" x y+ wprintf "%%%%Pages: %d\n" pagecount+ wPutStrLn "%%EOF"+ return a++-- | Global PostScript definitions used by the rendering engine.+global_ps_defs :: String+global_ps_defs = "/textbox { /b exch def /align exch def /y1 exch def /x1 exch def /y0 exch def /x0 exch def /dx x1 x0 sub def /dy y1 y0 sub def /d dx dx mul dy dy mul add sqrt def dup stringwidth pop /w exch def /fontscale w d le {d} {w} ifelse def gsave [dx dy dy neg dx x0 y0] concat 1 fontscale div dup scale fontscale w sub align mul b moveto show grestore } bind def\n"+ +-- | Render pages as PostScript.+pages_to_ps :: Document a -> PSWriter a+pages_to_ps (Document_Return a) = return a+pages_to_ps (Document_Page x y draw) = do+ page <- ps_next_page+ ps_add_bbox x y+ wprintf "%%%%Page: %d %d\n" page page+ wprintf "%%%%PageBoundingBox: 0 0 %d %d\n" (int_ceiling x) (int_ceiling y)+ wprintf "%%%%PageHiResBoundingBox: 0 0 %f %f\n" x y+ wPutStrLn "save"+ cont <- draw_to_ps draw+ wPutStrLn "showpage"+ wPutStrLn "restore"+ pages_to_ps cont+pages_to_ps (Document_Page_defer draw) = do+ page <- ps_next_page+ wprintf "%%%%Page: %d %d\n" page page+ wPutStrLn "%%PageBoundingBox: (atend)"+ wPutStrLn "%%PageHiResBoundingBox: (atend)"+ (x, y, cont) <- draw_to_ps draw+ wPutStrLn "showpage"+ wPutStrLn "%%PageTrailer"+ wprintf "%%%%PageBoundingBox: 0 0 %d %d\n" (int_ceiling x) (int_ceiling y)+ wprintf "%%%%PageHiResBoundingBox: 0 0 %f %f\n" x y+ ps_add_bbox x y+ pages_to_ps cont++-- ----------------------------------------------------------------------+-- ** Rendering to the Writer monad++-- | Render document as PostScript. The first argument is a+-- customization data structure.+render_ps_custom :: Custom -> Document a -> Writer a+render_ps_custom custom doc = + pswriter_run (document_to_ps custom doc)++-- ----------------------------------------------------------------------+-- * EPS output++-- $ Encapsulated PostScript (EPS) output is slightly different from+-- normal PostScript output. EPS is limited to a single page, and+-- contains no \"showpage\" command. We permit the user to print a+-- single page from a multi-page document, by specifying the page+-- number.++-- | Render a document as EPS. Since EPS only permits a single page of+-- output, the 'Page' parameter is used to specify which page (of a+-- potential multi-page document) should be printed. An error will be+-- thrown if the page number was out of range.+-- +-- Note: if the return value is not used, the remaining pages are+-- lazily skipped.+document_to_eps :: Custom -> Page -> Document a -> PSWriter a+document_to_eps custom page (Document_Return a) = + error "document_to_eps: requested page does not exist"+document_to_eps custom page (Document_Page x y draw) + | page == 1 = do+ -- EPS header+ wPutStrLn "%!PS-Adobe-3.0 EPSF-3.0"+ wPutStrLn "%%LanguageLevel: 2"+ when (creator custom /= "") $ do+ wprintf "%%%%Creator: %s\n" (creator custom)+ wprintf "%%%%BoundingBox: 0 0 %d %d\n" (int_ceiling x) (int_ceiling y)+ wprintf "%%%%HiResBoundingBox: 0 0 %f %f\n" x y+ wPutStrLn "%%Pages: 1"+ wPutStrLn "%%EndComments"+ wPutStrLn "%%Page: 1 1"+ wPutStrLn "save"+ wprintf "%s" global_ps_defs+ when (ps_defs custom /= "") $ do+ wprintf "%s" (ensure_nl $ ps_defs custom)+ cont <- draw_to_ps draw+ wPutStrLn "restore"+ wPutStrLn "%%EOF"+ let a = document_skip cont+ return a+ | otherwise = do+ let cont = draw_skip draw+ document_to_eps custom (page-1) cont+document_to_eps custom page (Document_Page_defer draw) + | page == 1 = do+ -- EPS header+ wPutStrLn "%!PS-Adobe-3.0 EPSF-3.0"+ wPutStrLn "%%LanguageLevel: 2"+ when (creator custom /= "") $ do+ wprintf "%%%%Creator: %s\n" (creator custom)+ wPutStrLn "%%BoundingBox: (atend)"+ wPutStrLn "%%HiResBoundingBox: (atend)"+ wPutStrLn "%%Pages: 1"+ wPutStrLn "%%EndComments"+ wPutStrLn "%%Page: 1 1"+ wPutStrLn "save"+ wprintf "%s" global_ps_defs+ when (ps_defs custom /= "") $ do+ wprintf "%s" (ensure_nl $ ps_defs custom)+ (x, y, cont) <- draw_to_ps draw+ wPutStrLn "restore"+ wPutStrLn "%%Trailer"+ wprintf "%%%%BoundingBox: 0 0 %d %d\n" (int_ceiling x) (int_ceiling y)+ wprintf "%%%%HiResBoundingBox: 0 0 %f %f\n" x y+ wPutStrLn "%%EOF"+ let a = document_skip cont+ return a+ | otherwise = do+ let (_, _, cont) = draw_skip draw+ document_to_eps custom (page-1) cont+ +-- | Render document as EPS. The first argument is a customization+-- data structure, and the second argument is the number of the page+-- to extract from the document.+render_eps_custom :: Custom -> Page -> Document a -> Writer a+render_eps_custom custom page doc = + pswriter_run (document_to_eps custom page doc)++-- ----------------------------------------------------------------------+-- * PDF output++-- ----------------------------------------------------------------------+-- ** Auxiliary functions++-- | Escape special characters in a string literal.+pdf_escape :: String -> String+pdf_escape [] = []+pdf_escape ('\\' : t) = '\\' : '\\' : pdf_escape t+pdf_escape ('(' : t) = '\\' : '(' : pdf_escape t+pdf_escape (')' : t) = '\\' : ')' : pdf_escape t+pdf_escape (h : t) = h : pdf_escape t++-- ----------------------------------------------------------------------+-- ** The PDF state++-- $ Creating PDF files requires some state: we need to keep track of+-- the current file position, page numbering, and object numbering. ++-- | A position in a file. The first byte is 0.+type Filepos = Integer++-- | A PDF object reference.+type Object = Integer++-- | A state to keep track of PDF document structure: current+-- character count, current TOC, current page, etc.+data PDF_State = PDF_State {+ pdf_filepos :: !Filepos, -- ^ Current position in file.+ pdf_obj :: !Object, -- ^ Object count.+ pdf_xref :: !(Map Object Filepos), -- ^ Cross-reference table.+ pdf_page :: !Page, -- ^ Next available page number.+ pdf_pagetable :: !(Map Page Object), -- ^ Page table.+ pdf_font :: !Integer, -- ^ Next available font number.+ pdf_fonttable :: !(Map String String) -- ^ Font table mapping each font's PostScript name to a local name.+ }+ +-- | The initial 'PDF_State'.+pdf_state_empty :: PDF_State+pdf_state_empty = PDF_State {+ pdf_filepos = 0,+ pdf_obj = 0,+ pdf_xref = Map.empty,+ pdf_page = 0,+ pdf_pagetable = Map.empty,+ pdf_font = 0,+ pdf_fonttable = Map.empty+ }++-- ----------------------------------------------------------------------+-- ** The PDFWriter monad++-- | The 'RawPDFWriter' monad is just a 'PDF_State' wrapped around+-- the 'Writer' monad. Its 'wPutChar' and 'wPutStr' methods+-- automatically keep track of the file position.+type RawPDFWriter = StateT PDF_State Writer++instance WriterMonad RawPDFWriter where+ wPutChar c = do+ lift (wPutChar c)+ pdf_inc_filepos 1+ wPutStr s = do + lift (wPutStr s)+ pdf_inc_filepos (toInteger $ length s)++-- | Boxed version of the 'RawPDFWriter' monad.+type PDFWriter = Boxed RawPDFWriter+ +-- | Run function for the 'PDFWriter' monad.+pdfwriter_run :: PDFWriter a -> Writer a+pdfwriter_run f = do+ evalStateT (unbox f) pdf_state_empty++-- ----------------------------------------------------------------------+-- *** Access functions for the PDFWriter monad++-- | Get the file position.+pdf_get_filepos :: PDFWriter Filepos+pdf_get_filepos = do+ s <- get+ return $ pdf_filepos s++-- | Add to the file position.+pdf_inc_filepos :: Integer -> RawPDFWriter ()+pdf_inc_filepos n = do+ s <- get+ let p = pdf_filepos s+ put s { pdf_filepos = p+n }++-- | Get the number of allocated objects. Note that objects are+-- allocated as 1, 2, ..., /n/; this function returns /n/.+pdf_get_objcount :: PDFWriter Object+pdf_get_objcount = do+ s <- get+ return $ pdf_obj s+ +-- | Allocate an unused object identifier.+pdf_next_object :: PDFWriter Object+pdf_next_object = do+ s <- get+ let o = pdf_obj s+ put s { pdf_obj = o+1 } + return $ o+1+ +-- | Add a cross reference to the cross reference table.+pdf_add_xref :: Object -> Filepos -> PDFWriter ()+pdf_add_xref obj pos = do+ s <- get+ let xref = pdf_xref s+ put s { pdf_xref = Map.insert obj pos xref }++-- | Retrieve the cross reference table.+pdf_get_xref :: PDFWriter (Map Object Filepos)+pdf_get_xref = do+ s <- get+ return $ pdf_xref s++-- | Get the page count.+pdf_get_pagecount :: PDFWriter Page+pdf_get_pagecount = do+ s <- get+ return $ pdf_page s+ +-- | Return the next page number.+pdf_next_page :: PDFWriter Page+pdf_next_page = do+ s <- get+ let p = pdf_page s+ put s { pdf_page = p+1 }+ return $ p+1++-- | Add a page to the page table.+pdf_add_pagetable :: Page -> Object -> PDFWriter ()+pdf_add_pagetable page obj = do+ s <- get+ let pagetable = pdf_pagetable s+ put s { pdf_pagetable = Map.insert page obj pagetable }++-- | Retrieve the page table.+pdf_get_pagetable :: PDFWriter (Map Page Object)+pdf_get_pagetable = do+ s <- get+ return $ pdf_pagetable s++-- | Look up the local font identifier for a font.+pdf_find_font :: String -> PDFWriter String +pdf_find_font font = do+ s <- get+ let t = pdf_fonttable s+ case Map.lookup font t of+ Nothing -> do+ let f = pdf_font s+ let fontname = "F" ++ show f+ put s { pdf_font = f+1, pdf_fonttable = Map.insert font fontname t }+ return fontname+ Just fontname -> return fontname+ +-- | Retrieve the font table.+pdf_get_fonttable :: PDFWriter (Map String String)+pdf_get_fonttable = do+ s <- get+ return $ pdf_fonttable s++-- | Clear the font table.+pdf_clear_fonttable :: PDFWriter ()+pdf_clear_fonttable = do+ s <- get+ put s { pdf_font = 0, pdf_fonttable = Map.empty }++-- ----------------------------------------------------------------------+-- *** Filters+ +-- | A version of 'with_filter' tailored to the 'PDFWriter' monad.+-- +-- This allows certain global state updates within the local block.+-- Specifically, updates to everything except the file position are+-- propagated from the inner to the outer block. The outer block's+-- file position is updated to reflect the encoded content's+-- length. From the inner block's point of view, the file position+-- starts from 0.+with_filter_pdf :: (String -> String) -> PDFWriter a -> PDFWriter a+with_filter_pdf encoding body = do+ s <- get+ let s' = s { pdf_filepos = 0 } -- pass everything except filepos to the body+ (a, s'') <- with_filter encoding $ do+ runStateT (unbox body) s'+ pos <- pdf_get_filepos+ put s'' { pdf_filepos = pos } -- pass everything except filepos from the body+ return a++-- ----------------------------------------------------------------------+-- *** Higher access functions++-- | Define an indirect PDF object with the given object id, which+-- must have previously been uniquely obtained with 'pdf_next_object'.+-- +-- This can be used to define objects with forward references: first+-- obtain an object id, then create references to the object, and+-- finally define the object.+-- +-- It should be used like this:+-- +-- > obj <- pdf_next_object+-- > ...+-- > pdf_deferred_object obj $ do+-- > <<object definition>>+pdf_deferred_object :: Object -> PDFWriter a -> PDFWriter a+pdf_deferred_object obj body = do+ pos <- pdf_get_filepos+ pdf_add_xref obj pos+ wprintf "%d 0 obj\n" obj+ a <- body+ wprintf "endobj\n"+ return a++-- | Define an indirect PDF object with a newly generated object id.+-- Return the object id. This essentially combines 'pdf_next_object'+-- and 'pdf_deferred_object' into a single function, and should be+-- used like this:+-- +-- > obj <- pdf_define_object $ do+-- > <<object definition>>+pdf_define_object :: PDFWriter a -> PDFWriter Object+pdf_define_object body = do+ obj <- pdf_next_object+ pdf_deferred_object obj body+ return obj++-- | Define a PDF stream object with the given object id, which must+-- have previously been uniquely obtained with 'pdf_next_object'. It+-- should be used like this:+-- +-- > obj <- pdf_next_object+-- > ...+-- > pdf_deferred_stream obj $ do+-- > <<stream contents>>+pdf_deferred_stream :: Object -> PDFWriter a -> PDFWriter a+pdf_deferred_stream obj body = do+ length_obj <- pdf_next_object+ (a, len) <- pdf_deferred_object obj $ do+ wprintf "<</Length %s>>\n" (objref length_obj)+ wPutStr "stream\n"+ x0 <- pdf_get_filepos+ a <- body+ x1 <- pdf_get_filepos+ wPutStr "\n"+ wPutStr "endstream\n"+ return (a, x1-x0)+ pdf_deferred_object length_obj $ do+ wprintf "%d\n" len+ return a++-- | Define a PDF stream object with a newly generated object+-- id. Return the object id. This should be used like this:+-- +-- > obj <- pdf_define_stream $ do+-- > <<stream contents>>+pdf_define_stream :: PDFWriter a -> PDFWriter Object +pdf_define_stream body = do+ obj <- pdf_next_object+ pdf_deferred_stream obj body+ return obj++-- | Define a compressed PDF stream object with the given object id,+-- which must have previously been uniquely obtained with+-- 'pdf_next_object'. It should be used like this:+-- +-- > obj <- pdf_next_object+-- > ...+-- > pdf_deferred_flate_stream obj $ do+-- > <<stream contents>>+pdf_deferred_flate_stream :: Object -> PDFWriter a -> PDFWriter a+pdf_deferred_flate_stream obj body = do+ length_obj <- pdf_next_object+ (a, len) <- pdf_deferred_object obj $ do+ wprintf "<</Length %s/Filter/FlateDecode>>\n" (objref length_obj)+ wPutStr "stream\n"+ x0 <- pdf_get_filepos+ a <- with_filter_pdf flate_filter body+ x1 <- pdf_get_filepos+ wPutStr "\n"+ wPutStr "endstream\n"+ return (a, x1-x0)+ pdf_deferred_object length_obj $ do+ wprintf "%d\n" len+ return a++-- | Create a direct object from a reference to an indirect object.+objref :: Object -> String+objref n = + show n ++ " 0 R"++-- | Write one line in the cross reference table. This must be exactly+-- 20 characters long, including the terminating newline.+wprintf_xref_entry :: Filepos -> Integer -> Char -> PDFWriter ()+wprintf_xref_entry pos gen c =+ wprintf "%010u %05u %c \n" pos gen c++-- | Format the cross reference table. Return the file position of the+-- cross reference table.+wprintf_xref :: PDFWriter Filepos+wprintf_xref = do+ xref <- pdf_get_xref+ n <- pdf_get_objcount+ pos <- pdf_get_filepos+ wprintf "xref\n"+ wprintf "0 %d\n" (n+1)+ wprintf_xref_entry 0 65535 'f'+ sequence_ [ case Map.lookup obj xref of + Nothing -> wprintf_xref_entry 0 0 'f' + Just p -> wprintf_xref_entry p 0 'n' | obj <- [1..n] ]+ return pos++-- ----------------------------------------------------------------------+-- ** Internal rendering to the PDFWriter monad++-- | Set the fill color.+fillcolor_to_pdf :: Color -> PDFWriter ()+fillcolor_to_pdf (Color_RGB r g b) = do+ wprintf "%f %f %f rg\n" r g b+fillcolor_to_pdf (Color_Gray v) = do+ wprintf "%f g\n" v++-- | Set the stroke color.+strokecolor_to_pdf :: Color -> PDFWriter ()+strokecolor_to_pdf (Color_RGB r g b) = do+ wprintf "%f %f %f RG\n" r g b+strokecolor_to_pdf (Color_Gray v) = do+ wprintf "%f G\n" v++-- | Set the font.+font_to_pdf :: Font -> PDFWriter ()+font_to_pdf (Font TimesRoman pt) = do+ fn <- pdf_find_font "Times-Roman"+ wprintf "/%s %f Tf\n" fn pt+font_to_pdf (Font Helvetica pt) = do+ fn <- pdf_find_font "Helvetica"+ wprintf "/%s %f Tf\n" fn pt++-- | Render a drawing command to PDF.+command_to_pdf :: DrawCommand -> PDFWriter ()+command_to_pdf (Newpath) = do+ wPutStr "n\n"+command_to_pdf (Moveto x y) = do+ wprintf "%f %f m\n" x y+command_to_pdf (Lineto x y) = do+ wprintf "%f %f l\n" x y+command_to_pdf (Curveto x1 y1 x2 y2 x y) = do+ wprintf "%f %f %f %f %f %f c\n" x1 y1 x2 y2 x y+command_to_pdf (Closepath) = do+ wPutStr "h\n"+command_to_pdf (Stroke) = do+ wPutStr "S\n"+command_to_pdf (Fill color) = do+ fillcolor_to_pdf color+ wPutStr "f\n"+command_to_pdf (FillStroke color) = do+ fillcolor_to_pdf color+ wPutStr "B\n"+command_to_pdf (TextBox align font color x0 y0 x1 y1 b s) = do+ let w = text_width font s+ dx = x1 - x0+ dy = y1 - y0+ d = sqrt (dx*dx + dy*dy)+ f = max w d+ dxf = if f > 0 then dx/f else 1+ dyf = if f > 0 then dy/f else 1+ xshift = (f-w) * align+ yshift = -b * nominalsize font+ wPutStr "BT\n"+ font_to_pdf font+ wprintf "%f %f %f %f %f %f Tm\n" dxf dyf (-dyf) dxf (x0 + xshift*dxf - yshift*dyf) (y0 + xshift*dyf + yshift*dxf)+ fillcolor_to_pdf color+ wprintf "(%s) Tj\n" (pdf_escape s)+ wPutStr "ET\n"+command_to_pdf (SetLineWidth x) = do+ wprintf "%f w\n" x+command_to_pdf (SetColor color) = do+ strokecolor_to_pdf color+command_to_pdf (Translate x y) = do+ wprintf "1 0 0 1 %f %f cm\n" x y+command_to_pdf (Scale x y) = do+ wprintf "%f 0 0 %f 0 0 cm\n" x y+command_to_pdf (Rotate angle) = do+ wprintf "%f %f %f %f 0 0 cm\n" c s (-s) c where+ c = cos (pi/180 * angle)+ s = sin (pi/180 * angle)+command_to_pdf (Comment s) = do+ wprintf "%% %s\n" (remove_nl s)+command_to_pdf (Subroutine draw alt) = do+ case custom_lookup Language_PDF alt of+ Just out -> wprintf "%s" (ensure_nl out)+ Nothing -> draw_to_pdf draw++-- | Render a draw action to PDF.+draw_to_pdf :: Draw a -> PDFWriter a+draw_to_pdf (Draw_Return x) = return x+draw_to_pdf (Draw_Write cmd cont) = do+ command_to_pdf cmd+ draw_to_pdf cont+draw_to_pdf (Draw_Block body) = do+ wprintf "q\n"+ cont <- draw_to_pdf body+ wprintf "Q\n"+ draw_to_pdf cont++-- | Render pages as PDF. The first argument is a reference to the+-- document's page tree node. +-- +-- Note: Acrobat reader cannot handle pages whose bounding box width+-- or height exceed 200 inches (14400 points). Therefore, we+-- automatically scale pages to be no greater than 199 inches.+pages_to_pdf :: Object -> Document a -> PDFWriter a+pages_to_pdf pagetree_obj (Document_Return a) = return a+pages_to_pdf pagetree_obj (Document_Page x y draw) = do+ let sc = 14328 / maximum [x, y, 14328]+ page <- pdf_next_page+ wprintf "%% Page %d\n" page+ pdf_clear_fonttable+ contents_obj <- pdf_next_object+ cont <- pdf_deferred_flate_stream contents_obj $ do+ when (sc /= 1.0) $ do+ draw_to_pdf $ do+ scale sc sc+ draw_to_pdf draw+ fonttable_obj <- pdf_define_object $ do+ fonttable <- pdf_get_fonttable+ wprintf "<<\n"+ sequence_ [ wprintf "/%s<</Type/Font/Subtype/Type1/BaseFont/%s>>\n" x f | (f,x) <- Map.toList fonttable ]+ wprintf ">>\n"+ page_obj <- pdf_define_object $ do+ wprintf "<</Type/Page/Parent %s/Resources<</ProcSet[/PDF]/Font %s>>/MediaBox[0 0 %f %f]/Contents %s>>\n" (objref pagetree_obj) (objref fonttable_obj) (x*sc) (y*sc) (objref contents_obj)+ pdf_add_pagetable page page_obj+ pages_to_pdf pagetree_obj cont+pages_to_pdf pagetree_obj (Document_Page_defer draw) = do+ page <- pdf_next_page+ wprintf "%% Page %d\n" page+ pdf_clear_fonttable+ contents_obj <- pdf_next_object+ (x, y, cont) <- pdf_deferred_stream contents_obj $ do+ draw_to_pdf draw+ fonttable_obj <- pdf_define_object $ do+ fonttable <- pdf_get_fonttable+ wprintf "<<\n"+ sequence_ [ wprintf "/%s<</Type/Font/Subtype/Type1/BaseFont/%s>>\n" x f | (f,x) <- Map.toList fonttable ]+ wprintf ">>\n"+ let sc = 14328 / maximum [x, y, 14328]+ scaled_contents_obj <- + if sc == 1.0 then do+ return contents_obj+ else do+ scale_obj <- pdf_define_stream $ do+ draw_to_pdf $ do+ scale sc sc+ obj <- pdf_define_object $ do+ wprintf "[%s %s]\n" (objref scale_obj) (objref contents_obj)+ return obj+ page_obj <- pdf_define_object $ do+ wprintf "<</Type/Page/Parent %s/Resources<</ProcSet[/PDF]/Font %s>>/MediaBox[0 0 %f %f]/Contents %s>>\n" (objref pagetree_obj) (objref fonttable_obj) (x*sc) (y*sc) (objref scaled_contents_obj)+ pdf_add_pagetable page page_obj+ pages_to_pdf pagetree_obj cont+ +-- | Render a document as PDF.+document_to_pdf :: Custom -> Document a -> PDFWriter a+document_to_pdf custom document = do+ -- global header+ wprintf "%%PDF-1.3\n"+ info_obj <- pdf_define_object $ do+ if (creator custom /= "") + then wprintf "<</Creator(%s)>>\n" (pdf_escape $ creator custom)+ else wprintf "<<>>\n"+ pagetree_obj <- pdf_next_object+ catalog_obj <- pdf_define_object $ do+ wprintf "<</Type/Catalog/Pages %s>>\n" (objref pagetree_obj)+ a <- pages_to_pdf pagetree_obj document+ pages <- pdf_get_pagecount+ pagetable <- pdf_get_pagetable+ pdf_deferred_object pagetree_obj $ do+ wprintf "<</Type/Pages/Count %d/Kids[\n" pages+ sequence_ [ wprintf "%s\n" (objref o) | o <- Map.elems pagetable ]+ wprintf "]>>\n"+ xref_pos <- wprintf_xref+ wprintf "trailer\n"+ objcount <- pdf_get_objcount+ wprintf "<</Size %d/Root %s/Info %s>>\n" objcount (objref catalog_obj) (objref info_obj)+ wprintf "startxref\n"+ wprintf "%d\n" xref_pos+ wprintf "%%%%EOF\n"+ return a++-- ----------------------------------------------------------------------+-- ** Rendering to the Writer monad++-- | Render document as PDF. The first argument is a+-- customization data structure.+render_pdf_custom :: Custom -> Document a -> Writer a+render_pdf_custom custom doc = pdfwriter_run (document_to_pdf custom doc)++-- ----------------------------------------------------------------------+-- * Generic output functions++-- $BACKENDS +-- +-- The following commands can be used to render documents to various+-- available formats. The available formats are PostScript, PDF, EPS,+-- and an ASCII-based debugging format. Output can be written to+-- standard output, to a file, or to a string.+ +-- | Available graphics formats for rendering.+data RenderFormat = + Format_PS -- ^ PostScript.+ | Format_PDF -- ^ Portable Document Format.+ | Format_EPS Integer -- ^ Encapsulated PostScript. The integer+ -- argument specifies which single page to+ -- extract from the document.+ | Format_Debug -- ^ An ASCII-based debugging format.+ deriving Show++-- | Does the format require raw binary output?+is_binary_format :: RenderFormat -> Bool+is_binary_format Format_PS = False+is_binary_format Format_PDF = True+is_binary_format (Format_EPS page) = False+is_binary_format Format_Debug = False++-- ----------------------------------------------------------------------+-- ** Rendering with custom format++-- $CUSTOMRENDER+-- +-- The following are versions of the generic rendering functions that+-- also take a customization data structure as an additional+-- parameter.++-- | Render a document to the 'Writer' monad, using the given output+-- format and customization data structure.+render_custom :: RenderFormat -> Custom -> Document a -> Writer a+render_custom Format_PS = render_ps_custom+render_custom Format_PDF = render_pdf_custom+render_custom (Format_EPS page) = (\c -> render_eps_custom c page)+render_custom Format_Debug = \c -> render_ascii++-- | Render a document to a file, using the given output format and+-- customization data structure.+render_custom_file :: Handle -> RenderFormat -> Custom -> Document a -> IO a+render_custom_file h format custom d = do+ when (is_binary_format format) $ do+ hSetBinaryMode h True+ writer_to_file h (render_custom format custom d)++-- | Render a document to standard output, using the given output+-- format and customization data structure.+render_custom_stdout :: RenderFormat -> Custom -> Document a -> IO a+render_custom_stdout = render_custom_file stdout++-- | Render a document to a string, using the given output format and+-- customization data structure.+render_custom_string :: RenderFormat -> Custom -> Document a -> String+render_custom_string format custom d =+ writer_to_string (render_custom format custom d) ++-- ----------------------------------------------------------------------+-- ** Rendering without custom format++-- | Render a document to the 'Writer' monad, using the given output format.+render :: RenderFormat -> Document a -> Writer a+render format doc = render_custom format custom doc++-- | Render a document to a file, using the given output format.+render_file :: Handle -> RenderFormat -> Document a -> IO a+render_file h format doc = render_custom_file h format custom doc++-- | Render a document to standard output, using the given output format.+render_stdout :: RenderFormat -> Document a -> IO a+render_stdout = render_file stdout++-- | Render a document to a string, using the given output format.+render_string :: RenderFormat -> Document a -> String+render_string format doc = render_custom_string format custom doc
+ LICENSE view
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+ Setup.hs view
@@ -0,0 +1,2 @@+import Distribution.Superdoc+main = superdocMain
+ easyrender.cabal view
@@ -0,0 +1,87 @@+-- The name of the package.+name: easyrender++-- The package version. See the Haskell package versioning policy (PVP) +-- for standards guiding when and how versions should be incremented.+-- http://www.haskell.org/haskellwiki/Package_versioning_policy+-- PVP summary: +-+------- breaking API changes+-- | | +----- non-breaking API additions+-- | | | +--- code changes with no API change+version: 0.1.0.0++-- A short (one-line) description of the package.+synopsis: User-friendly creation of EPS, PostScript, and PDF files++-- A longer description of the package.+description: ++ This module provides efficient functions for rendering vector+ graphics to a number of formats, including EPS, PostScript, and+ PDF. It provides an abstraction for multi-page documents, as well+ as a set of graphics primitives for page descriptions. + .+ The graphics model is similar to that of the PostScript and PDF+ languages, but we only implement a subset of their functionality.+ Care has been taken that graphics rendering is done efficiently and+ as lazily as possible; documents are rendered \"on the fly\",+ without the need to store the whole document in memory.+ .+ The provided document description model consists of two separate+ layers of abstraction:+ .+ * /drawing/ is concerned with placing marks on a fixed surface, and+ takes place in the 'Draw' monad;+ .+ * /document structure/ is concerned with a sequence of pages, their+ bounding boxes, and other meta-data. It takes place in the+ 'Document' monad.+ .+ In principle, the functionality provided by EasyRender is similar to+ a subset of Cairo; however, EasyRender is lightweight and at least+ an order of magnitude faster.++-- URL for the project homepage or repository.+homepage: http://www.mathstat.dal.ca/~selinger/easyrender/++-- The license under which the package is released.+license: GPL-3++-- The file containing the license text.+license-file: LICENSE++-- The package author(s).+author: Peter Selinger++-- An email address to which users can send suggestions, bug reports, and +-- patches.+maintainer: selinger@mathstat.dal.ca++-- A copyright notice.+copyright: Copyright (c) 2012-2013 Peter Selinger++-- A classification category for future use by the package catalogue+-- Hackage. These categories have not yet been specified, but the+-- upper levels of the module hierarchy make a good start.+category: Graphics++-- The type of build used by this package.+build-type: Custom++-- Constraint on the version of Cabal needed to build this package.+cabal-version: >=1.8++-- A list of additional files to be included in source distributions+-- built with setup sdist.+extra-source-files:+ images/*.png ChangeLog++library+ -- Modules exported by the library.+ exposed-modules: Graphics.EasyRender, Graphics.EasyRender.Auxiliary, Graphics.EasyRender.Internal+ + -- Modules included in this library but not exported.+ -- other-modules: + + -- Other library packages from which modules are imported.+ build-depends: base ==4.6.*, zlib ==0.5.*, mtl ==2.1.*, bytestring ==0.10.*, containers ==0.5.*, superdoc ==0.1.*+
+ images/textbox.png view
binary file changed (absent → 9043 bytes)