| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Codec.Picture.Png
Contents
Description
Module used for loading & writing 'Portable Network Graphics' (PNG) files.
A high level API is provided. It loads and saves images for you while hiding all the details about PNG chunks.
Basic functions for PNG handling are decodePng, encodePng
and encodePalettedPng. Convenience functions are provided
for direct file handling and using DynamicImages.
The loader has been validated against the pngsuite (http:/www.libpng.orgpubpngpngsuite.html)
- class PngSavable a where
- encodePng :: Image a -> ByteString
- encodePngWithMetadata :: Metadatas -> Image a -> ByteString
- decodePng :: ByteString -> Either String DynamicImage
- decodePngWithMetadata :: ByteString -> Either String (DynamicImage, Metadatas)
- writePng :: PngSavable pixel => FilePath -> Image pixel -> IO ()
- encodeDynamicPng :: DynamicImage -> Either String ByteString
- encodePalettedPng :: Palette -> Image Pixel8 -> Either String ByteString
- encodePalettedPngWithMetadata :: Metadatas -> Palette -> Image Pixel8 -> Either String ByteString
- writeDynamicPng :: FilePath -> DynamicImage -> IO (Either String Bool)
High level functions
class PngSavable a where
Encode an image into a png if possible.
Minimal complete definition
Methods
encodePng :: Image a -> ByteString
Transform an image into a png encoded bytestring, ready to be written as a file.
encodePngWithMetadata :: Metadatas -> Image a -> ByteString
Encode a png using some metadatas. The following metadata keys will
be stored in a tEXt field :
TitleDescriptionAuthorCopyrightSoftwareCommentDisclaimerSourceWarningUnknownusing the key present in the constructor.
the followings metadata will bes tored in the gAMA chunk.
The followings metadata will be stored in a pHYs chunk
decodePng :: ByteString -> Either String DynamicImage
Transform a raw png image to an image, without modifying the underlying pixel type. If the image is greyscale and < 8 bits, a transformation to RGBA8 is performed. This should change in the future. The resulting image let you manage the pixel types.
This function can output the following pixel types:
- PixelY8
- PixelY16
- PixelYA8
- PixelYA16
- PixelRGB8
- PixelRGB16
- PixelRGBA8
- PixelRGBA16
decodePngWithMetadata :: ByteString -> Either String (DynamicImage, Metadatas)
Same as decodePng but also extract meta datas present
in the files.
writePng :: PngSavable pixel => FilePath -> Image pixel -> IO ()
Helper function to directly write an image as a png on disk.
encodeDynamicPng :: DynamicImage -> Either String ByteString
Encode a dynamic image in bmp if possible, supported pixel type are :
- Y8
- Y16
- YA8
- YA16
- RGB8
- RGB16
- RGBA8
- RGBA16
encodePalettedPng :: Palette -> Image Pixel8 -> Either String ByteString
Encode a paletted image as a color indexed 8-bit PNG. the palette must have between 1 and 256 values in it.
encodePalettedPngWithMetadata :: Metadatas -> Palette -> Image Pixel8 -> Either String ByteString
Equivalent to encodePalettedPng but allow writing of metadatas.
writeDynamicPng :: FilePath -> DynamicImage -> IO (Either String Bool)
Write a dynamic image in a .png image file if possible. The same restriction as encodeDynamicPng apply.