ImageNav.chs

{-# LANGUAGE CPP #-}
-- -*-haskell-*-
--  GIMP Toolkit (GTK) Widget ImageNav
--
--  Author : Andy Stewart
--
--  Created: 19 Aug 2010
--
--  Copyright (C) 2010 Andy Stewart
--
--  This library is free software; you can redistribute it and/or
--  modify it under the terms of the GNU Lesser General Public
--  License as published by the Free Software Foundation; either
--  version 2.1 of the License, or (at your option) any later version.
--
--  This library is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
--  Lesser General Public License for more details.
--
-- |
-- Maintainer  : gtk2hs-users@lists.sourceforge.net
-- Stability   : provisional
-- Portability : portable (depends on GHC)
--
module Graphics.UI.Gtk.ImageView.ImageNav (
-- * Details
-- | 'ImageNav' is a popup window that shows a downscaled preview of the pixbuf that 'ImageView' is
-- showing. The user can drag around a rectangle which indicates the current view of the image.
-- 
-- This class is used by 'ImageScrollWin' itself. It is probably not very useful for clients of this
-- library.
-- 
-- 'ImageNav' has the same keybindings that 'ImageView' has. All keypresses that it receives are
-- passed along to the view.

-- * Types
   ImageNav,
   ImageNavClass,

-- * Methods
   imageNavNew,
   imageNavGetPixbuf,
   imageNavGrab,
   imageNavRelease,
   imageNavShowAndGrab,
) where

import Control.Monad	(liftM)
import Data.Maybe    (fromMaybe)

import Graphics.UI.Gtk.Abstract.Object	(makeNewObject)
import Graphics.UI.Gtk.ImageView.Enums
import System.Glib.Attributes
import System.Glib.FFI
import System.Glib.UTFString

{#import Graphics.UI.Gtk.ImageView.Signals#}
{#import Graphics.UI.Gtk.ImageView.Types#}
{#import System.Glib.Properties#}

{# context lib="gtk" prefix="gtk" #}

-- | Creates a new 'ImageNav' for showing thumbnails of the view.
imageNavNew :: ImageViewClass view => view -> IO ImageNav
imageNavNew view = 
  makeNewObject mkImageNav $
  liftM (castPtr :: Ptr Widget -> Ptr ImageNav) $
  {# call unsafe gtk_image_nav_new #}
    (toImageView view)

-- | Returns the downscaled pixbuf of the views pixbuf that this 'ImageNav' shows, or 'Nothing' if that
-- pixbuf has not been created yet.
imageNavGetPixbuf :: ImageNavClass nav => nav
                  -> IO (Maybe Pixbuf) -- ^ returns the pixbuf in the navigation area this image navigator shows, or 'Nothing' if none exist.
imageNavGetPixbuf nav = 
  maybeNull (wrapNewGObject mkPixbuf) $
  {#call gtk_image_nav_get_pixbuf #}
    (toImageNav nav)

-- |
imageNavGrab :: ImageNavClass nav => nav -> IO ()
imageNavGrab nav =
  {#call gtk_image_nav_grab #}
    (toImageNav nav)

-- |
imageNavRelease :: ImageNavClass nav => nav -> IO ()
imageNavRelease nav =
  {#call gtk_image_nav_release #}
    (toImageNav nav)

-- | Show the 'ImageNav' centered around the point (@centerX@, @centerY@) and grab mouse and keyboard
-- events. The grab continues until a button release event is received which causes the widget to hide.
imageNavShowAndGrab :: ImageNavClass nav => nav 
                    -> Int -- ^ @centerX@ x coordinate of center position 
                    -> Int -- ^ @centerY@ y coordinate of center position 
                    -> IO ()
imageNavShowAndGrab nav centerX centerY =
  {#call gtk_image_nav_show_and_grab #}
    (toImageNav nav)
    (fromIntegral centerX)
    (fromIntegral centerY)