Copyright	(c) Tim Docker 2014
License	BSD-style (see chart/COPYRIGHT)
Safe Haskell	None
Language	Haskell98

Graphics.Rendering.Chart.Backend

Contents

The backend Monad
Backend Operations
Backend Helpers
Text Metrics
Line Types
Fill Types
Font and Text Types

Description

This module provides the API for drawing operations abstracted to drive arbitrary Backend.

Synopsis

type BackendProgram a = Program ChartBackendInstr a
fillPath :: Path -> BackendProgram ()
strokePath :: Path -> BackendProgram ()
drawText :: Point -> String -> BackendProgram ()
textSize :: String -> BackendProgram TextSize
withTransform :: Matrix -> BackendProgram a -> BackendProgram a
withClipRegion :: Rect -> BackendProgram a -> BackendProgram a
withFontStyle :: FontStyle -> BackendProgram a -> BackendProgram a
withFillStyle :: FillStyle -> BackendProgram a -> BackendProgram a
withLineStyle :: LineStyle -> BackendProgram a -> BackendProgram a
getPointAlignFn :: BackendProgram (Point -> Point)
getCoordAlignFn :: BackendProgram (Point -> Point)
data TextSize = TextSize {
- textSizeWidth :: Double
- textSizeAscent :: Double
- textSizeDescent :: Double
- textSizeYBearing :: Double
- textSizeHeight :: Double
}
data LineCap
- = LineCapButt
- | LineCapRound
- | LineCapSquare
data LineJoin
- = LineJoinMiter
- | LineJoinRound
- | LineJoinBevel
data LineStyle = LineStyle {
- _line_width :: Double
- _line_color :: AlphaColour Double
- _line_dashes :: [Double]
- _line_cap :: LineCap
- _line_join :: LineJoin
}
line_width :: Lens' LineStyle Double
line_color :: Lens' LineStyle (AlphaColour Double)
line_dashes :: Lens' LineStyle [Double]
line_cap :: Lens' LineStyle LineCap
line_join :: Lens' LineStyle LineJoin
newtype FillStyle = FillStyleSolid {
- _fill_color :: AlphaColour Double
}
data FontWeight
- = FontWeightNormal
- | FontWeightBold
data FontSlant
- = FontSlantNormal
- | FontSlantItalic
- | FontSlantOblique
data FontStyle = FontStyle {
- _font_name :: String
- _font_size :: Double
- _font_slant :: FontSlant
- _font_weight :: FontWeight
- _font_color :: AlphaColour Double
}
data HTextAnchor
- = HTA_Left
- | HTA_Centre
- | HTA_Right
data VTextAnchor
- = VTA_Top
- | VTA_Centre
- | VTA_Bottom
- | VTA_BaseLine
font_name :: Lens' FontStyle String
font_size :: Lens' FontStyle Double
font_slant :: Lens' FontStyle FontSlant
font_weight :: Lens' FontStyle FontWeight
font_color :: Lens' FontStyle (AlphaColour Double)
type AlignmentFn = Point -> Point
data AlignmentFns
vectorAlignmentFns :: AlignmentFns
bitmapAlignmentFns :: AlignmentFns

The backend Monad

type BackendProgram a = Program ChartBackendInstr a #

A BackendProgram provides the capability to render a chart somewhere.

The coordinate system of the backend has its initial origin (0,0) in the top left corner of the drawing plane. The x-axis points towards the top right corner and the y-axis points towards the bottom left corner. The unit used by coordinates, the font size, and lengths is the always the same, but depends on the backend. All angles are measured in radians.

The line, fill and font style are set to their default values initially.

Information about the semantics of the instructions can be found in the documentation of ChartBackendInstr.

Backend Operations

fillPath :: Path -> BackendProgram () #

Fill the given path using the current FillStyle. The given path will be closed prior to filling. This function does not perform alignment operations on the path. See Path for the exact semantic of paths.

strokePath :: Path -> BackendProgram () #

Stroke the outline of the given path using the current LineStyle. This function does not perform alignment operations on the path. See Path for the exact semantic of paths.

drawText :: Point -> String -> BackendProgram () #

Draw a single-line textual label anchored by the baseline (vertical) left (horizontal) point. Uses the current FontStyle for drawing.

textSize :: String -> BackendProgram TextSize #

Calculate a TextSize object with rendering information about the given string without actually rendering it.

withTransform :: Matrix -> BackendProgram a -> BackendProgram a #

Apply the given transformation in this local environment when drawing. The given transformation is applied after the current transformation. This means both are combined.

withClipRegion :: Rect -> BackendProgram a -> BackendProgram a #

Use the given clipping rectangle when drawing in this local environment. The new clipping region is intersected with the given clip region. You cannot escape the clip!

withFontStyle :: FontStyle -> BackendProgram a -> BackendProgram a #

Use the given font style in this local environment when drawing text.

An implementing backend is expected to guarentee to support the following font families: serif, sans-serif and monospace;

If the backend is not able to find or load a given font it is required to fall back to a custom fail-safe font and use it instead.

withFillStyle :: FillStyle -> BackendProgram a -> BackendProgram a #

Use the given fill style in this local environment when filling paths.

withLineStyle :: LineStyle -> BackendProgram a -> BackendProgram a #

Use the given line style in this local environment when stroking paths.

Backend Helpers

getPointAlignFn :: BackendProgram (Point -> Point) #

Get the point alignment function

getCoordAlignFn :: BackendProgram (Point -> Point) #

Get the coordinate alignment function

Text Metrics

data TextSize #

Text metrics returned by textSize.

Constructors

TextSize
Fields textSizeWidth :: Double The total width of the text. textSizeAscent :: Double The ascent or space above the baseline. textSizeDescent :: Double The decent or space below the baseline. textSizeYBearing :: Double The Y bearing. textSizeHeight :: Double The total height of the text.

Instances

Eq TextSize #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: TextSize -> TextSize -> Bool # (/=) :: TextSize -> TextSize -> Bool #
Show TextSize #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> TextSize -> ShowS # show :: TextSize -> String # showList :: [TextSize] -> ShowS #

Line Types

data LineCap #

The different supported line ends.

Constructors

LineCapButt	Just cut the line straight.
LineCapRound	Make a rounded line end.
LineCapSquare	Make a square that ends the line.

Instances

Eq LineCap #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: LineCap -> LineCap -> Bool # (/=) :: LineCap -> LineCap -> Bool #
Ord LineCap #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: LineCap -> LineCap -> Ordering # (<) :: LineCap -> LineCap -> Bool # (<=) :: LineCap -> LineCap -> Bool # (>) :: LineCap -> LineCap -> Bool # (>=) :: LineCap -> LineCap -> Bool # max :: LineCap -> LineCap -> LineCap # min :: LineCap -> LineCap -> LineCap #
Show LineCap #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> LineCap -> ShowS # show :: LineCap -> String # showList :: [LineCap] -> ShowS #

data LineJoin #

The different supported ways to join line ends.

Constructors

LineJoinMiter	Extends the outline until they meet each other.
LineJoinRound	Draw a circle fragment to connet line end.
LineJoinBevel	Like miter, but cuts it off if a certain threshold is exceeded.

Instances

Eq LineJoin #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: LineJoin -> LineJoin -> Bool # (/=) :: LineJoin -> LineJoin -> Bool #
Ord LineJoin #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: LineJoin -> LineJoin -> Ordering # (<) :: LineJoin -> LineJoin -> Bool # (<=) :: LineJoin -> LineJoin -> Bool # (>) :: LineJoin -> LineJoin -> Bool # (>=) :: LineJoin -> LineJoin -> Bool # max :: LineJoin -> LineJoin -> LineJoin # min :: LineJoin -> LineJoin -> LineJoin #
Show LineJoin #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> LineJoin -> ShowS # show :: LineJoin -> String # showList :: [LineJoin] -> ShowS #

data LineStyle #

Data type for the style of a line.

Constructors

LineStyle
Fields _line_width :: Double The thickness of a line in device units. _line_color :: AlphaColour Double The color of a line. _line_dashes :: [Double] The dash pattern. Every value at a even index gives a dash width and every value at a odd index gives a gap width in device units. _line_cap :: LineCap How to end a line. _line_join :: LineJoin How to connect two lines.

Instances

Eq LineStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: LineStyle -> LineStyle -> Bool # (/=) :: LineStyle -> LineStyle -> Bool #
Show LineStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> LineStyle -> ShowS # show :: LineStyle -> String # showList :: [LineStyle] -> ShowS #
Default LineStyle #	The default line style.
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods def :: LineStyle #

line_width :: Lens' LineStyle Double #

line_color :: Lens' LineStyle (AlphaColour Double) #

line_dashes :: Lens' LineStyle [Double] #

line_cap :: Lens' LineStyle LineCap #

line_join :: Lens' LineStyle LineJoin #

Fill Types

newtype FillStyle #

Abstract data type for a fill style.

The contained action sets the required fill style in the rendering state.

Constructors

FillStyleSolid
Fields _fill_color :: AlphaColour Double

Instances

Eq FillStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: FillStyle -> FillStyle -> Bool # (/=) :: FillStyle -> FillStyle -> Bool #
Show FillStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> FillStyle -> ShowS # show :: FillStyle -> String # showList :: [FillStyle] -> ShowS #
Default FillStyle #	The default fill style.
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods def :: FillStyle #

Font and Text Types

data FontWeight #

The possible weights of a font.

Constructors

FontWeightNormal	Normal font style without weight.
FontWeightBold	Bold font.

Instances

Eq FontWeight #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: FontWeight -> FontWeight -> Bool # (/=) :: FontWeight -> FontWeight -> Bool #
Ord FontWeight #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: FontWeight -> FontWeight -> Ordering # (<) :: FontWeight -> FontWeight -> Bool # (<=) :: FontWeight -> FontWeight -> Bool # (>) :: FontWeight -> FontWeight -> Bool # (>=) :: FontWeight -> FontWeight -> Bool # max :: FontWeight -> FontWeight -> FontWeight # min :: FontWeight -> FontWeight -> FontWeight #
Show FontWeight #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> FontWeight -> ShowS # show :: FontWeight -> String # showList :: [FontWeight] -> ShowS #
Default FontWeight #	The default font weight.
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods def :: FontWeight #

data FontSlant #

The possible slants of a font.

Constructors

FontSlantNormal	Normal font style without slant.
FontSlantItalic	With a slight slant.
FontSlantOblique	With a greater slant.

Instances

Eq FontSlant #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: FontSlant -> FontSlant -> Bool # (/=) :: FontSlant -> FontSlant -> Bool #
Ord FontSlant #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: FontSlant -> FontSlant -> Ordering # (<) :: FontSlant -> FontSlant -> Bool # (<=) :: FontSlant -> FontSlant -> Bool # (>) :: FontSlant -> FontSlant -> Bool # (>=) :: FontSlant -> FontSlant -> Bool # max :: FontSlant -> FontSlant -> FontSlant # min :: FontSlant -> FontSlant -> FontSlant #
Show FontSlant #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> FontSlant -> ShowS # show :: FontSlant -> String # showList :: [FontSlant] -> ShowS #
Default FontSlant #	The default font slant.
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods def :: FontSlant #

data FontStyle #

Data type for a font.

Constructors

FontStyle
Fields _font_name :: String The font family or font face to use. _font_size :: Double The height of the rendered font in device coordinates. _font_slant :: FontSlant The slant to render with. _font_weight :: FontWeight The weight to render with. _font_color :: AlphaColour Double The color to render text with.

Instances

Eq FontStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: FontStyle -> FontStyle -> Bool # (/=) :: FontStyle -> FontStyle -> Bool #
Show FontStyle #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> FontStyle -> ShowS # show :: FontStyle -> String # showList :: [FontStyle] -> ShowS #
Default FontStyle #	The default font style.
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods def :: FontStyle #

data HTextAnchor #

Possible horizontal anchor points for text.

Constructors

HTA_Left
HTA_Centre
HTA_Right

Instances

Eq HTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: HTextAnchor -> HTextAnchor -> Bool # (/=) :: HTextAnchor -> HTextAnchor -> Bool #
Ord HTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: HTextAnchor -> HTextAnchor -> Ordering # (<) :: HTextAnchor -> HTextAnchor -> Bool # (<=) :: HTextAnchor -> HTextAnchor -> Bool # (>) :: HTextAnchor -> HTextAnchor -> Bool # (>=) :: HTextAnchor -> HTextAnchor -> Bool # max :: HTextAnchor -> HTextAnchor -> HTextAnchor # min :: HTextAnchor -> HTextAnchor -> HTextAnchor #
Show HTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> HTextAnchor -> ShowS # show :: HTextAnchor -> String # showList :: [HTextAnchor] -> ShowS #

data VTextAnchor #

Possible vertical anchor points for text.

Constructors

VTA_Top
VTA_Centre
VTA_Bottom
VTA_BaseLine

Instances

Eq VTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods (==) :: VTextAnchor -> VTextAnchor -> Bool # (/=) :: VTextAnchor -> VTextAnchor -> Bool #
Ord VTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods compare :: VTextAnchor -> VTextAnchor -> Ordering # (<) :: VTextAnchor -> VTextAnchor -> Bool # (<=) :: VTextAnchor -> VTextAnchor -> Bool # (>) :: VTextAnchor -> VTextAnchor -> Bool # (>=) :: VTextAnchor -> VTextAnchor -> Bool # max :: VTextAnchor -> VTextAnchor -> VTextAnchor # min :: VTextAnchor -> VTextAnchor -> VTextAnchor #
Show VTextAnchor #
Instance details Defined in Graphics.Rendering.Chart.Backend.Types Methods showsPrec :: Int -> VTextAnchor -> ShowS # show :: VTextAnchor -> String # showList :: [VTextAnchor] -> ShowS #

font_name :: Lens' FontStyle String #

font_size :: Lens' FontStyle Double #

font_slant :: Lens' FontStyle FontSlant #

font_weight :: Lens' FontStyle FontWeight #

font_color :: Lens' FontStyle (AlphaColour Double) #

type AlignmentFn = Point -> Point #

A function to align points for a certain rendering device.

data AlignmentFns #

Holds the point and coordinate alignment function.

vectorAlignmentFns :: AlignmentFns #

Alignment to render on vector based graphics.

bitmapAlignmentFns :: AlignmentFns #

Alignment to render on raster based graphics.