我想拍摄两张不同的图像(取自图像文件,如.png),并在不同位置多次绘制一张图像。生成的图像应显示在屏幕上或生成新的图像文件,以较容易的方式。我将通过进一步的操作来拍摄新图像并进一步绘制
是否有任何Haskell库允许我这样做?
答案 0 :(得分:1)
您可以使用JuicyPixels执行此类操作:
module Triangles where
import Codec.Picture
import LineGraphics
{-| Parameterize color smoothly as a function of angle -}
colorWheel :: Float -> Colour
colorWheel x = (r, g, b, a)
where
r = floor $ (cos x + 1) * (255 / 2)
g = floor $ (sin x + 1) * (255 / 2)
b = floor $ (cos (x+(pi/2)) + 1) * (255 / 2)
a = 255
{-| Draw a triangle centered about the point (x, y) -}
triangle :: Point -> Path
triangle (x, y) =
[ (x - k, y - k)
, (x + k, y - k)
, (x, y + k)
, (x - k, y - k)
]
where
size = 30
k = size / 2
{-|
Draw 'n' equally-spaced triangles at a radius of 'r' about a center
point, '(x, y)'.
-}
triangles :: Float -> Radius -> Vector -> Picture
triangles n r (x, y) =
[ (colorWheel theta, tri theta) | theta <- steps n ]
where
tri theta = triangle ((r * cos theta) + x, (r * sin theta) + y)
{-| Interpolate the range [0, 2pi] by 'n' steps -}
steps :: Float -> [Float]
steps n = map (\i -> i * (2*pi/n)) [0 .. n]
我们将使用此支持代码模块:
module LineGraphics (
Point, Vector, Line, Path, Picture, Colour, Radius,
black,
drawPicture,
) where
import Graphics.Rasterific hiding (Point, Vector, Line, Path, polygon)
import Graphics.Rasterific.Texture
import Codec.Picture
type Radius = Float
type Point = (Float, Float)
type Vector = (Float, Float)
type Line = (Point, Point)
type Path = [Point]
type Picture = [(Colour, Path)]
type Colour = (Int, Int, Int, Int) -- red, green, blue, opacity
black = (0, 0, 0, 255)
drawPicture :: Float -> Picture -> Image PixelRGBA8
drawPicture linewidth picture =
renderDrawing 800 800 (toColour black) $
mapM_ renderFn picture
where
renderFn (col, path) = withTexture (uniformTexture $ toColour col) (drawPath path)
drawPath points = stroke linewidth JoinRound (CapRound, CapStraight 0) $
polyline (map (\(x, y) -> V2 x y) points)
toColour (a,b,c,d) = PixelRGBA8
(fromIntegral a) (fromIntegral b) (fromIntegral c) (fromIntegral d)