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{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE RecordWildCards #-}
{-# OPTIONS_HADDOCK hide #-}
-- | Helper functions for rendering bitmaps
module Graphics.Gloss.Internals.Rendering.Bitmap
( Rectangle(..)
, BitmapData(..)
, BitmapFormat(..), PixelFormat(..), RowOrder(..)
, bitmapPath
, freeBitmapData)
where
import Data.Data
import Foreign
-- | Represents a rectangular section in a bitmap
data Rectangle
= Rectangle
{ rectPos :: (Int, Int) -- ^ x- and y-pos in the bitmap in pixels
, rectSize :: (Int, Int) -- ^ width/height of the area in pixelsi
}
deriving (Show, Read, Eq, Ord, Data, Typeable)
-- | Abstract 32-bit RGBA bitmap data.
data BitmapData
= BitmapData
{ bitmapDataLength :: Int -- length (in bytes)
, bitmapFormat :: BitmapFormat
, bitmapSize :: (Int, Int) -- ^ width, height in pixels
, bitmapCacheMe :: Bool
, bitmapPointer :: (ForeignPtr Word8) }
deriving (Eq, Data, Typeable)
-- | Description of how the bitmap is layed out in memory.
--
-- * Prior version of Gloss assumed `BitmapFormat BottomToTop PxABGR`
--
data BitmapFormat
= BitmapFormat
{ rowOrder :: RowOrder
, pixelFormat :: PixelFormat }
deriving (Eq, Data, Typeable, Show, Ord)
-- | Order of rows in an image are either:
--
-- * `TopToBottom` - the top row, followed by the next-lower row and so on.
-- * `BottomToTop` - the bottom row followed by the next-higher row and so on.
--
data RowOrder
= TopToBottom
| BottomToTop
deriving (Eq, Data, Typeable, Show, Ord, Enum, Bounded)
-- | Pixel formats describe the order of the color channels in memory.
data PixelFormat
= PxRGBA | PxABGR
deriving (Eq, Data, Typeable, Show, Ord, Enum, Bounded)
instance Show BitmapData where
show _ = "BitmapData"
-- | Generates the point path to display the bitmap centred
bitmapPath :: Float -> Float -> [(Float, Float)]
bitmapPath width height
= [(-width', -height'), (width', -height'), (width', height'), (-width', height')]
where width' = width / 2
height' = height / 2
-- | Frees the allocated memory given to OpenGL to avoid a memory leak
freeBitmapData :: Ptr Word8 -> IO ()
freeBitmapData p = free p
{-# INLINE freeBitmapData #-}
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