[Gtk2hs-commit] (main branch): Add pixbufRenderThresholdAlpha

[Axel S. <si...@co...>]

diffing dir...
Sat Feb 20 13:13:59 EST 2010  ar...@rp...
  * Add pixbufRenderThresholdAlpha
  Ignore-this: f7c25ecfc1aba9f8437d7b49bda903be
    {
    hunk ./gtk/Graphics/UI/Gtk/Gdk/Pixbuf.chs 113
    -  pixbufGetFromDrawable
    +  pixbufGetFromDrawable,
    +
    +  pixbufRenderThresholdAlpha,
    +  pixbufRenderPixmapAndMaskForColormap
    hunk ./gtk/Graphics/UI/Gtk/Gdk/Pixbuf.chs 130
    +import Graphics.UI.Gtk.Gdk.Pixmap (Bitmap, Pixmap)
    hunk ./gtk/Graphics/UI/Gtk/Gdk/Pixbuf.chs 717
    +
    +
    +
    +-- | Takes the opacity values in a rectangular portion of a pixbuf and
    +-- thresholds them to produce a bi-level alpha mask that can be used
    +-- as a clipping mask for a drawable.
    +pixbufRenderThresholdAlpha ::
    +    Pixbuf -- ^ A pixbuf.
    + -> Bitmap -- ^ Bitmap where the bilevel mask will be painted to.
    + -> Int  -- ^ Source X coordinate.
    + -> Int  -- ^ source Y coordinate.
    + -> Int -- ^ Destination X coordinate.
    + -> Int -- ^ Destination Y coordinate.
    + -> Int -- ^ Width of region to threshold, or -1 to use pixbuf width
    + -> Int -- ^ Height of region to threshold, or -1 to use pixbuf height
    + -> Int -- ^ Opacity values below this will be painted as zero; all other values will be painted as one.
    + -> IO ()
    +pixbufRenderThresholdAlpha src dest srcX srcY destX destY w h at =
    +  withForeignPtr (unPixmap dest) $ \destPtr ->
    +  {#call unsafe pixbuf_render_threshold_alpha#} src
    +                                                (castPtr destPtr)
    +                                                (fromIntegral srcX)
    +                                                (fromIntegral srcY)
    +                                                (fromIntegral destX)
    +                                                (fromIntegral destY)
    +                                                (fromIntegral w)
    +                                                (fromIntegral h)
    +                                                (fromIntegral at)
    +
    +
    +
    +
    +
    +-- | Creates a pixmap and a mask bitmap which are returned and renders
    +-- a pixbuf and its corresponding thresholded alpha mask to them. This
    +-- is merely a convenience function; applications that need to render
    +-- pixbufs with dither offsets or to given drawables should use
    +-- 'Graphics.UI.Gtk.Gdk.Drawable.drawPixbuf', and
    +-- 'pixbufRenderThresholdAlpha'.
    +--
    +-- The pixmap that is created uses the 'Colormap' specified by
    +-- colormap. This colormap must match the colormap of the window where
    +-- the pixmap will eventually be used or an error will result.
    +--
    +-- If the pixbuf does not have an alpha channel, then the returned
    +-- mask will be @Nothing@.
    +--
    +pixbufRenderPixmapAndMaskForColormap ::
    +    Pixbuf                    -- ^ A pixbuf.
    + -> Colormap                  -- ^ A Colormap
    + -> Int                       -- ^ Threshold value for opacity values
    + -> IO (Pixmap, Maybe Bitmap) -- ^ (Created pixmap, created mask)
    +pixbufRenderPixmapAndMaskForColormap pixbuf colormap threshold =
    +  alloca $ \pmRetPtr ->
    +    alloca $ \bmRetPtr -> do
    +      {#call unsafe pixbuf_render_pixmap_and_mask_for_colormap#} pixbuf
    +                                                                 colormap
    +                                                                 (castPtr pmRetPtr) -- seems to reject Pixmap**, so cast
    +                                                                 (castPtr bmRetPtr)
    +                                                                 (fromIntegral threshold)
    +      pm <- constructNewGObject mkPixmap (peek pmRetPtr :: IO (Ptr Pixmap))
    +      bm <- maybeNull (constructNewGObject mkPixmap) (peek bmRetPtr :: IO (Ptr Bitmap))
    +      return (pm, bm)
    +
    +
    }