SDL.Compositor

This module provides the means for declarative image generation using sdl2 primitives as a basis. Atomical operations for image composition are rotation, translation, mirroring, color modulation, changing blend modes and primitive drawing.

This packages aims to provide a basic interface via type classes. This means that you could write your own implementation but still use eventual utility functions provided by this package. The authors decided to split the functionality into several typeclasses to allow partial implementations while preserving type safety.

Interface

class Compositor c where

A Compositor is a thing that can overlap, rotate and mirror objects.

Methods

overC :: c -> c -> c infixr 5

overC x y positions x over y. The meaning of this depends on the context. For Textures and drawings this means that x should be drawn after y was drawn.

rotateC :: Double -> c -> c

flipC :: V2 Bool -> c -> c

This function takes a 'V2 Bool' that represents mirroring action. The first component of the vector represents mirroring along the y-axis (horizontally) and the second component represents mirroring along the x-axis (vertically).

Instances

Compositor (CompositingNode a)

Compositor (c a) => Compositor (ResIndependent c a)

class Blender b where

This class modells a graphics object that supports switching of BlendMode.

Methods

blendMode :: BlendMode -> b -> b

This method sets the BlendMode of an object. If the object has children, their BlendMode property will be preserved.

Instances

Blender (CompositingNode a)

Blender (c a) => Blender (ResIndependent c a)

class Manipulator m where

This class models a graphics object that supports color modulation.

Methods

modulateAlphaM :: Int -> m -> m

Modulate the alpha channel of picture. This behavior stacks multiplicatively.

modulateRedM :: Int -> m -> m

Modulate the red channel of picture. This behavior stacks multiplicatively.

modulateGreenM :: Int -> m -> m

Modulate the green channel of picture. This behavior stacks multiplicatively.

modulateBlueM :: Int -> m -> m

Modulate the blue channel of picture. This behavior stacks multiplicatively.

Instances

Manipulator (CompositingNode a)

Manipulator (c a) => Manipulator (ResIndependent c a)

class Drawer d where

Methods

rectangleC :: V2 Int -> Color -> d

lineC :: V2 Int -> Color -> d

filledRectangleC :: V2 Int -> Color -> d

Instances

Drawer (CompositingNode a)

class AbsoluteSize c where

Methods

translateA :: V2 Int -> c a -> c a

sizedA :: V2 Int -> a -> c a

Instances

AbsoluteSize CompositingNode

class Texture tex where

Minimal complete definition

textureAlphaMod, textureColorMod, textureBlendMode, textureWidth, textureHeight, destroyTexture

Methods

textureAlphaMod :: tex -> StateVar Word8

textureColorMod :: tex -> StateVar (V3 Word8)

textureBlendMode :: tex -> StateVar BlendMode

textureWidth :: tex -> IO Int

textureHeight :: tex -> IO Int

textureDims :: tex -> IO (V2 Int)

destroyTexture :: tex -> IO ()

Instances

Texture Texture

class Renderer rend where

Methods

rendererDrawColor :: rend -> StateVar (V4 Word8)

clear :: rend -> IO ()

present :: rend -> IO ()

drawRect :: rend -> Maybe (Rectangle Int) -> IO ()

drawLine :: rend -> Point V2 Int -> Point V2 Int -> IO ()

Instances

Renderer Renderer

class Renderable rend tex where

This class modells that something can be rendered to another thing.

Methods

copyEx

Arguments

:: rend

rendering context

-> tex

texture

-> Maybe (Rectangle Int)

source rectangle

-> Maybe (Rectangle Int)

destination rectangle

-> Double

rotation

-> Maybe (Point V2 Int)

rotation center

-> V2 Bool

flipping

-> IO ()

createTexture :: rend -> PixelFormat -> TextureAccess -> V2 Int -> IO tex

rendererRenderTarget :: rend -> StateVar (Maybe tex)

Instances

Renderable Renderer Texture

Utility

withZIndex :: (Compositor c, Monoid c) => [(Int, c)] -> c

Arrange all given compositions in one composition.

This function takes a list of pairs where the first element of the pair is the z-index and the second element is the composition. Elements of with a higher z-index will be rendered "in front of" elements with lower indices. If elements have the same index then the element that comes first in the list will be drawn over all the later ones.

This method can only arrange compositions that are in the "the same list of arguments". That means that

withZIndex [(1,a),(2,b)] `overC` withZIndex [(3,c)]

will always result in b being rendered "in front of" a and c, no matter how large the z-index of c is.

Implementation

data CompositingNode a

A compositing node represents a compound graphical resource.

Instances

AbsoluteSize CompositingNode

Eq a => Eq (CompositingNode a)

Show a => Show (CompositingNode a)

Monoid (CompositingNode a)

mempty represents no painting at all. Also

mappend a b == overC a b

Manipulator (CompositingNode a)

Drawer (CompositingNode a)

Blender (CompositingNode a)

Compositor (CompositingNode a)

runRenderer :: forall tex rend. (Texture tex, Renderer rend, Renderable rend tex) => rend -> CompositingNode tex -> IO ()

Render a composed image.

Colors

data Color

Represents the value of color.

rgba :: Word8 -> Word8 -> Word8 -> Word8 -> Color

construct a color value from red green blue and alpha values.