FRP.Helm.Graphics

Contains all the data structures and functions for composing and rendering graphics.

Types

data Element

A data structure describing something that can be rendered to the screen. Elements are the most important structure in Helm. Games essentially feed the engine a stream of elements which are then rendered directly to the screen. The usual way to render art in a Helm game is to call off to the collage function, which essentially renders a collection of forms together.

Constructors

CollageElement Int Int [Form]

ImageElement (Int, Int) Int Int FilePath Bool

TextElement Text

Instances

Eq Element

Show Element

data Text

A data structure describing a piece of formatted text.

Constructors

Text

Fields

textUTF8 :: String

textColor :: Color

fontTypeface :: String

fontSize :: Double

fontWeight :: FontWeight

fontSlant :: FontSlant

Instances

Eq Text

Show Text

data Form

A data structure describing a form. A form is essentially a notion of a transformed graphic, whether it be an element or shape. See FormStyle for an insight into what sort of graphics can be wrapped in a form.

Constructors

Form

Fields

theta :: Double

scalar :: Double

x :: Double

y :: Double

style :: FormStyle

Instances

Eq Form

Show Form

data FormStyle

A data structure describing a few ways that graphics that can be wrapped in a form and hence transformed.

Constructors

PathForm LineStyle Path

ShapeForm (Either LineStyle FillStyle) Shape

ElementForm Element

GroupForm Matrix [Form]

Instances

Eq FormStyle

Show FormStyle

data FillStyle

A data structure describing how a shape or path looks when filled.

Constructors

Solid Color

Texture String

Gradient Gradient

Instances

Eq FillStyle

Show FillStyle

data LineCap

A data structure describing the shape of the ends of a line.

Constructors

Flat

Round

Padded

Instances

Enum LineCap

Eq LineCap

Ord LineCap

Show LineCap

data LineJoin

A data structure describing the shape of the join of a line, i.e. where separate line segments join. The Sharp variant takes an argument to limit the length of the join.

Constructors

Smooth

Sharp Double

Clipped

Instances

Eq LineJoin

Show LineJoin

data LineStyle

A data structure describing how a shape or path looks when stroked.

Constructors

LineStyle

Fields

color :: Color

width :: Double

cap :: LineCap

join :: LineJoin

dashing :: [Double]

dashOffset :: Double

Instances

Eq LineStyle

Show LineStyle

type Path = [(Double, Double)]

A data type made up a collection of points that form a path when joined.

data Shape

A data structure describing a some sort of graphically representable object, such as a polygon formed from a set of points or a rectangle.

Constructors

PolygonShape Path

RectangleShape (Double, Double)

ArcShape (Double, Double) Double Double Double (Double, Double)

Instances

Eq Shape

Show Shape

Elements

image :: Int -> Int -> FilePath -> Element

Create an element from an image with a given width, height and image file path. If the image dimensions are not the same as given, then it will stretch/shrink to fit. Only PNG files are supported currently.

fittedImage :: Int -> Int -> FilePath -> Element

Create an element from an image with a given width, height and image file path. If the image dimensions are not the same as given, then it will only use the relevant pixels (i.e. cut out the given dimensions instead of scaling). If the given dimensions are bigger than the actual image, than irrelevant pixels are ignored.

croppedImage :: (Int, Int) -> Int -> Int -> FilePath -> Element

Create an element from an image by cropping it with a certain position, width, height and image file path. This can be used to divide a single image up into smaller ones.

collage :: Int -> Int -> [Form] -> Element

Create an element from a collection of forms, with width and height arguments. Can be used to directly render a collection of forms.

 collage 800 600 [move (100, 100) $ filled red $ square 100,
                  move (100, 100) $ outlined (solid white) $ circle 50]

Styles & Forms

defaultLine :: LineStyle

Creates the default line style. By default, the line is black with a width of 1, flat caps and regular sharp joints.

solid :: Color -> LineStyle

Create a solid line style with a color.

dashed :: Color -> LineStyle

Create a dashed line style with a color.

dotted :: Color -> LineStyle

Create a dotted line style with a color.

filled :: Color -> Shape -> Form

Creates a form from a shape by filling it with a specific color.

textured :: String -> Shape -> Form

Creates a form from a shape with a tiled texture and image file path.

gradient :: Gradient -> Shape -> Form

Creates a form from a shape filled with a gradient.

outlined :: LineStyle -> Shape -> Form

Creates a form from a shape by outlining it with a specific line style.

traced :: LineStyle -> Path -> Form

Creates a form from a path by tracing it with a specific line style.

sprite :: Int -> Int -> (Int, Int) -> FilePath -> Form

Creates a form from a image file path with additional position, width and height arguments. Allows you to splice smaller parts from a single image.

toForm :: Element -> Form

Creates a form from an element.

Grouping

group :: [Form] -> Form

Groups a collection of forms into a single one.

groupTransform :: Matrix -> [Form] -> Form

Groups a collection of forms into a single one, also applying a matrix transformation.

Transforming

rotate :: Double -> Form -> Form

Rotates a form by an amount (in radians).

scale :: Double -> Form -> Form

Scales a form by an amount, e.g. scaling by 2.0 will double the size.

move :: (Double, Double) -> Form -> Form

Moves a form relative to its current position.

moveX :: Double -> Form -> Form

Moves a form's x-coordinate relative to its current position.

moveY :: Double -> Form -> Form

Moves a form's y-coordinate relative to its current position.

Paths

path :: [(Double, Double)] -> Path

Creates a path for a collection of points.

segment :: (Double, Double) -> (Double, Double) -> Path

Creates a path from a line segment, i.e. a start and end point.

Shapes

polygon :: Path -> Shape

Creates a shape from a path (a set of points).

rect :: Double -> Double -> Shape

Creates a rectangular shape with a width and height.

square :: Double -> Shape

Creates a square shape with a side length.

oval :: Double -> Double -> Shape

Creates an oval shape with a width and height.

circle :: Double -> Shape

Creates a circle shape with a radius.

ngon :: Int -> Double -> Shape

Creates a generic n-sided polygon (e.g. octagon, pentagon, etc) with an amount of sides and radius.