Tue Oct 30 11:38:25 PDT 2007 ag...@im...
* Add support for getting the stride and image data of an image surface
This wraps the cairo functions:
cairo_image_surface_get_stride
cairo_image_surface_get_data
Note that these functions were introduced in cairo 1.2, and so this sets a new
high bar for gtk2hs cairo.
hunk ./cairo/Graphics/Rendering/Cairo/Internal/Surfaces/Image.chs 26
+{#fun image_surface_get_stride as imageSurfaceGetStride { withSurface* `Surface' } -> `Int'#}
+{#fun image_surface_get_data as imageSurfaceGetData { withSurface* `Surface' } -> `(Ptr CUChar)' id#}
hunk ./cairo/Graphics/Rendering/Cairo.hs.pp 172
+ , imageSurfaceGetStride
+ , imageSurfaceGetData
hunk ./cairo/Graphics/Rendering/Cairo.hs.pp 242
+import Foreign.Ptr (castPtr)
+import qualified Data.ByteString as BS
hunk ./cairo/Graphics/Rendering/Cairo.hs.pp 1526
--- [_$_]
+--
hunk ./cairo/Graphics/Rendering/Cairo.hs.pp 1552
+-- | Get the number of bytes from the start of one row to the start of the
+-- next. If the image data contains no padding, then this is equal to
+-- the pixel depth * the width.
+imageSurfaceGetStride :: Surface -> Render Int
+imageSurfaceGetStride = liftIO . Internal.imageSurfaceGetStride
+
+-- | Return a ByteString of the image data for a surface. In order to remain
+-- safe the returned ByteString is a copy of the data. This is a little
+-- slower than returning a pointer into the image surface object itself, but
+-- much safer
+imageSurfaceGetData :: Surface -> IO BS.ByteString
+imageSurfaceGetData a = do
+ height <- Internal.imageSurfaceGetHeight a
+ stride <- Internal.imageSurfaceGetStride a
+ ptr <- Internal.imageSurfaceGetData a
+ BS.copyCStringLen (castPtr ptr, height * stride)
+
|
