Add windowOpacity

Author: dpwiz

src/SDL/Raw/Video.hs

@@ -52,6 +52,7 @@ module SDL.Raw.Video (
   getWindowID,
   getWindowMaximumSize,
   getWindowMinimumSize,
+  getWindowOpacity,
   getWindowPixelFormat,
   getWindowPosition,
   getWindowSize,
@@ -73,6 +74,7 @@ module SDL.Raw.Video (
   setWindowIcon,
   setWindowMaximumSize,
   setWindowMinimumSize,
+  setWindowOpacity,
   setWindowPosition,
   setWindowSize,
   setWindowTitle,
@@ -282,6 +284,7 @@ foreign import ccall "SDL.h SDL_GetWindowGrab" getWindowGrabFFI :: Window -> IO
 foreign import ccall "SDL.h SDL_GetWindowID" getWindowIDFFI :: Window -> IO Word32
 foreign import ccall "SDL.h SDL_GetWindowMaximumSize" getWindowMaximumSizeFFI :: Window -> Ptr CInt -> Ptr CInt -> IO ()
 foreign import ccall "SDL.h SDL_GetWindowMinimumSize" getWindowMinimumSizeFFI :: Window -> Ptr CInt -> Ptr CInt -> IO ()
+foreign import ccall "SDL.h SDL_GetWindowOpacity" getWindowOpacityFFI :: Window -> Ptr CFloat -> IO ()
 foreign import ccall "SDL.h SDL_GetWindowPixelFormat" getWindowPixelFormatFFI :: Window -> IO Word32
 foreign import ccall "SDL.h SDL_GetWindowPosition" getWindowPositionFFI :: Window -> Ptr CInt -> Ptr CInt -> IO ()
 foreign import ccall "SDL.h SDL_GetWindowSize" getWindowSizeFFI :: Window -> Ptr CInt -> Ptr CInt -> IO ()
@@ -303,6 +306,7 @@ foreign import ccall "SDL.h SDL_SetWindowGrab" setWindowGrabFFI :: Window -> Boo
 foreign import ccall "SDL.h SDL_SetWindowIcon" setWindowIconFFI :: Window -> Ptr Surface -> IO ()
 foreign import ccall "SDL.h SDL_SetWindowMaximumSize" setWindowMaximumSizeFFI :: Window -> CInt -> CInt -> IO ()
 foreign import ccall "SDL.h SDL_SetWindowMinimumSize" setWindowMinimumSizeFFI :: Window -> CInt -> CInt -> IO ()
+foreign import ccall "SDL.h SDL_SetWindowOpacity" setWindowOpacityFFI :: Window -> CFloat -> IO ()
 foreign import ccall "SDL.h SDL_SetWindowPosition" setWindowPositionFFI :: Window -> CInt -> CInt -> IO ()
 foreign import ccall "SDL.h SDL_SetWindowSize" setWindowSizeFFI :: Window -> CInt -> CInt -> IO ()
 foreign import ccall "SDL.h SDL_SetWindowTitle" setWindowTitleFFI :: Window -> CString -> IO ()
@@ -643,6 +647,10 @@ getWindowMinimumSize :: MonadIO m => Window -> Ptr CInt -> Ptr CInt -> m ()
 getWindowMinimumSize v1 v2 v3 = liftIO $ getWindowMinimumSizeFFI v1 v2 v3
 {-# INLINE getWindowMinimumSize #-}
 
+getWindowOpacity :: MonadIO m => Window -> Ptr CFloat -> m ()
+getWindowOpacity v1 v2 = liftIO $ getWindowOpacityFFI v1 v2
+{-# INLINE getWindowOpacity #-}
+
 getWindowPixelFormat :: MonadIO m => Window -> m Word32
 getWindowPixelFormat v1 = liftIO $ getWindowPixelFormatFFI v1
 {-# INLINE getWindowPixelFormat #-}
@@ -727,6 +735,10 @@ setWindowMinimumSize :: MonadIO m => Window -> CInt -> CInt -> m ()
 setWindowMinimumSize v1 v2 v3 = liftIO $ setWindowMinimumSizeFFI v1 v2 v3
 {-# INLINE setWindowMinimumSize #-}
 
+setWindowOpacity :: MonadIO m => Window -> CFloat -> m ()
+setWindowOpacity v1 v2 = liftIO $ setWindowOpacityFFI v1 v2
+{-# INLINE setWindowOpacity #-}
+
 setWindowPosition :: MonadIO m => Window -> CInt -> CInt -> m ()
 setWindowPosition v1 v2 v3 = liftIO $ setWindowPositionFFI v1 v2 v3
 {-# INLINE setWindowPosition #-}

src/SDL/Video.hs

@@ -25,6 +25,7 @@ module SDL.Video
   -- * Window Attributes
   , windowMinimumSize
   , windowMaximumSize
+  , windowOpacity
   , windowSize
   , windowBordered
   , windowBrightness
@@ -611,6 +612,22 @@ windowMinimumSize (Window win) = makeStateVar getWindowMinimumSize setWindowMini
       Raw.getWindowMinimumSize win wptr hptr
       V2 <$> peek wptr <*> peek hptr
 
+-- | Get or set the opacity of a window.
+--
+-- This 'StateVar' can be modified using '$=' and the current value retrieved with 'get'.
+--
+-- See @<https://wiki.libsdl.org/SDL_SetWindowOpacity SDL_SetWindowOpacity>@ and @<https://wiki.libsdl.org/SDL_GetWindowOpacity SDL_GetWindowOpacity>@ for C documentation.
+windowOpacity :: Window -> StateVar CFloat
+windowOpacity (Window win) = makeStateVar getWindowOpacity setWindowOpacity
+  where
+  setWindowOpacity opacity = Raw.setWindowOpacity win opacity
+
+  getWindowOpacity =
+    liftIO $
+    alloca $ \optr -> do
+      Raw.getWindowOpacity win optr
+      peek optr
+
 createRenderer :: MonadIO m => Window -> CInt -> RendererConfig -> m Renderer
 createRenderer (Window w) driver config =
   liftIO . fmap Renderer $