Safe Haskell	None
Language	Haskell98

Graphics.GD.ByteString.Lazy

Contents

Types
Creating and copying images
Memory management
Loading images
- JPEG
- PNG
- GIF
Saving images
- JPEG
- PNG
- GIF
Getting image information
Querying
Manipulating images
Drawing
Text
Colors

Synopsis

Types

data Image #

type Size = (Int, Int) #

type Point = (Int, Int) #

type Color = CInt #

Creating and copying images

newImage :: Size -> IO Image #

Create a new empty image.

copyImage :: Image -> IO Image #

Make a copy of an image.

copyRegion #

Arguments

:: Point	Source upper left-hand corner
-> Size	Size of copied region
-> Image	Source image
-> Point	Destination upper left-hand corner
-> Image	Destination image
-> IO ()

Copy a region of one image into another

copyRegionScaled #

Arguments

:: Point	Source upper left-hand corner
-> Size	Size of source region
-> Image	Source image
-> Point	Destination upper left-hand corner
-> Size	Size of destination region
-> Image	Destination image
-> IO ()

Copy a region of one image into another, rescaling the region

Memory management

withImage #

Arguments

:: IO Image	Image creation action.
-> (Image -> IO b)	Some operation on the image. The result should not reference the `Image`.
-> IO b

Creates an image, performs an operation on the image, and frees it. This function allows block scoped management of Image objects. If you are handling large images, the delay before the finalizer which frees the image runs may cause significant temporary extra memory use. Use this function to force the image to be freed as soons as you are done with it. Note that it is unsafe to hold on to the Image after the function is done.

Loading images

JPEG

loadJpegFile :: FilePath -> IO Image #

Load a JPEG image from a file.

loadJpegData #

Arguments

:: Int	Buffer size.
-> Ptr a	Buffer with image data.
-> IO Image

Load a JPEG image from a buffer.

loadJpegByteString :: ByteString -> IO Image #

Load a JPEG image from a ByteString

PNG

loadPngFile :: FilePath -> IO Image #

Load a PNG image from a file.

loadPngData #

Arguments

:: Int	Buffer size.
-> Ptr a	Buffer with image data.
-> IO Image

Load a PNG image from a buffer.

loadPngByteString :: ByteString -> IO Image #

Load a PNG image from a ByteString

GIF

loadGifFile :: FilePath -> IO Image #

Load a GIF image from a file.

loadGifData #

Arguments

:: Int	Buffer size.
-> Ptr a	Buffer with image data.
-> IO Image

Load a GIF image from a buffer.

loadGifByteString :: ByteString -> IO Image #

Load a GIF image from a ByteString

Saving images

JPEG

saveJpegFile #

Arguments

:: Int	quality: 0-95, or negative for default quality.
-> FilePath
-> Image
-> IO ()

Save an image as a JPEG file.

saveJpegByteString :: Int -> Image -> IO ByteString #

Write a JPEG format ByteString of an image.

PNG

savePngFile :: FilePath -> Image -> IO () #

Save an image as a PNG file.

savePngByteString :: Image -> IO ByteString #

Write a PNG format ByteString of an image.

GIF

saveGifFile :: FilePath -> Image -> IO () #

Save an image as a GIF file.

saveGifByteString :: Image -> IO ByteString #

Write a GIF format ByteString of an image.

Getting image information

imageSize #

Arguments

:: Image
-> IO (Int, Int)	(width, height)

Get the size of an image.

Querying

getPixel :: (Int, Int) -> Image -> IO Color #

Retrieves the color index or the color values of a particular pixel.

Manipulating images

resizeImage #

Arguments

:: Int	width in pixels of output image
-> Int	height in pixels of output image
-> Image
-> IO Image

Resize an image to a give size.

rotateImage #

Arguments

:: Int	1 for 90 degrees counter-clockwise, 2 for 180 degrees, etc.
-> Image
-> IO Image

Rotate an image by a multiple of 90 degrees counter-clockwise.

Drawing

fillImage :: Color -> Image -> IO () #

Fill the entire image with the given color.

drawFilledRectangle #

Arguments

:: Point	Upper left corner
-> Point	Lower right corner
-> Color
-> Image
-> IO ()

drawFilledEllipse #

Arguments

:: Point	Center
-> Size	Width and height
-> Color
-> Image
-> IO ()

drawLine #

Arguments

:: Point	Start
-> Point	End
-> Color
-> Image
-> IO ()

drawArc #

Arguments

:: Point	Center
-> Size	Width and height
-> Int	Starting position (degrees)
-> Int	Ending position (degrees)
-> Color
-> Image
-> IO ()

antiAliased :: (Color -> Image -> IO a) -> Color -> Image -> IO a #

Use anti-aliasing when performing the given drawing function. This can cause a segault with some gd versions.

setPixel :: Point -> Color -> Image -> IO () #

Text

useFontConfig :: Bool -> IO Bool #

Globally switch from using font file names to fontconfig paths | for fonts in drawString (and measureString).

drawString #

Arguments

:: ByteString	Font name
-> Double	Font point size
-> Double	Angle in counterclockwise radians
-> Point	Origin
-> ByteString	Text, including HTML entities
-> Color
-> Image
-> IO (Point, Point, Point, Point)	Bounding box of the drawn text

Draw a string using the FreeType 2.x library

measureString #

Arguments

:: ByteString	Font name
-> Double	Font point size
-> Double	Angle in counterclockwise radians
-> Point	Origin
-> ByteString	Text, including HTML entities
-> Color
-> IO (Point, Point, Point, Point)	Bounding box of the drawn text

Measure a string using the FreeType 2.x library. This computes the bounding box but does not actually draw the string to any image.

drawStringCircle #

Arguments

:: Point	Center of text path circle
-> Double	Outer radius of text
-> Double	Fraction of radius occupied by text
-> Double	Portion of circle arc filled by text
-> ByteString	Font name
-> Double	Font size hint
-> ByteString	Text to write on the top of the circle
-> ByteString	Text to write on the bottom of the circle
-> Color	Text color
-> Image
-> IO ()

Draw strings around the top and bottom of a torus

Colors

rgb #

Arguments

:: Int	Red (0-255)
-> Int	Green (0-255)
-> Int	Blue (0-255)
-> Color

rgba #

Arguments

:: Int	Red (0-255)
-> Int	Green (0-255)
-> Int	Blue (0-255)
-> Int	Alpha (0-127), 0 is opaque, 127 is transparent
-> Color

toRGBA :: Color -> (Int, Int, Int, Int) #