Copyright | (c) Tim Docker 2014 |
---|---|
License | BSD-style (see chart/COPYRIGHT) |
Safe Haskell | None |
Language | Haskell98 |
This module provides the API for drawing operations abstracted
to arbitrary ChartBackend
s.
- type ChartBackend a = Program ChartBackendInstr a
- fillPath :: Path -> ChartBackend ()
- strokePath :: Path -> ChartBackend ()
- drawText :: Point -> String -> ChartBackend ()
- textSize :: String -> ChartBackend TextSize
- withTransform :: Matrix -> ChartBackend a -> ChartBackend a
- withClipRegion :: Rect -> ChartBackend a -> ChartBackend a
- withFontStyle :: FontStyle -> ChartBackend a -> ChartBackend a
- withFillStyle :: FillStyle -> ChartBackend a -> ChartBackend a
- withLineStyle :: LineStyle -> ChartBackend a -> ChartBackend a
- getPointAlignFn :: ChartBackend (Point -> Point)
- getCoordAlignFn :: ChartBackend (Point -> Point)
- data TextSize = TextSize {}
- data LineCap
- data LineJoin
- data LineStyle = 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
- newtype FillStyle = FillStyleSolid {}
- data FontWeight
- data FontSlant
- data FontStyle = FontStyle {}
- data HTextAnchor
- data VTextAnchor
- 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 ChartBackend a = Program ChartBackendInstr a
A ChartBackend
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 -> ChartBackend ()
strokePath :: Path -> ChartBackend ()
drawText :: Point -> String -> ChartBackend ()
Draw a single-line textual label anchored by the baseline (vertical)
left (horizontal) point. Uses the current FontStyle
for drawing.
textSize :: String -> ChartBackend TextSize
Calculate a TextSize
object with rendering information
about the given string without actually rendering it.
withTransform :: Matrix -> ChartBackend a -> ChartBackend 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 -> ChartBackend a -> ChartBackend 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 -> ChartBackend a -> ChartBackend 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 -> ChartBackend a -> ChartBackend a
Use the given fill style in this local environment when filling paths.
withLineStyle :: LineStyle -> ChartBackend a -> ChartBackend a
Use the given line style in this local environment when stroking paths.
Backend Helpers
getPointAlignFn :: ChartBackend (Point -> Point)
Get the point alignment function
getCoordAlignFn :: ChartBackend (Point -> Point)
Get the coordinate alignment function
Text Metrics
data TextSize
Text metrics returned by textSize
.
TextSize | |
|
Line Types
data LineCap
The different supported line ends.
LineCapButt | Just cut the line straight. |
LineCapRound | Make a rounded line end. |
LineCapSquare | Make a square that ends the line. |
data LineJoin
The different supported ways to join line ends.
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. |
data LineStyle
Data type for the style of a line.
LineStyle | |
|
line_dashes :: Lens' LineStyle [Double]
Fill Types
newtype FillStyle
Abstract data type for a fill style.
The contained action sets the required fill style in the rendering state.
Font and Text Types
data FontWeight
The possible weights of a font.
FontWeightNormal | Normal font style without weight. |
FontWeightBold | Bold font. |
Eq FontWeight | |
Ord FontWeight | |
Show FontWeight | |
Default FontWeight | The default font weight. |
data FontSlant
The possible slants of a font.
FontSlantNormal | Normal font style without slant. |
FontSlantItalic | With a slight slant. |
FontSlantOblique | With a greater slant. |
data FontStyle
Data type for a font.
FontStyle | |
|
data HTextAnchor
Possible horizontal anchor points for text.
data VTextAnchor
Possible vertical anchor points for text.
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.