save
및 restore
작업은 이미지가 다시 계산되는지 여부와 관련이 없습니다.
let redrawStaticLayers = do
(width, height) <- widgetGetSize window
drawWin <- widgetGetDrawWindow window
background <- createImageSurface FormatARGB32 width height
foreground <- createImageSurface FormatARGB32 width height
let clear = do
save
setOperator OperatorClear
paint
restore
renderWith background $ do
clear
drawClockBackground True width height
renderWith foreground $ do
clear
drawClockForeground True width height
writeIORef backgroundRef (Just background)
writeIORef foregroundRef (Just foreground)
onRealize window redrawStaticLayers
sizeRef <- newIORef (initialSize, initialSize)
timeoutHandlerRef <- newIORef Nothing
window `on` configureEvent $ do
(w,h) <- eventSize
liftIO $ do
size <- readIORef sizeRef
writeIORef sizeRef (w,h)
when (size /= (w,h)) $ do
background <- readIORef backgroundRef
foreground <- readIORef foregroundRef
maybe (return()) surfaceFinish background
maybe (return()) surfaceFinish foreground
writeIORef backgroundRef Nothing
writeIORef foregroundRef Nothing
timeoutHandler <- readIORef timeoutHandlerRef
maybe (return()) timeoutRemove timeoutHandler
handler <- timeoutAddFull (do
writeIORef timeoutHandlerRef Nothing
redrawStaticLayers
widgetQueueDraw window
return False
) priorityDefaultIdle 300
writeIORef timeoutHandlerRef (Just handler)
return False
window `on` exposeEvent $ do
drawWin <- eventWindow
exposeRegion <- eventRegion
liftIO $ do
(width, height) <- drawableGetSize drawWin
background <- readIORef backgroundRef
foreground <- readIORef foregroundRef
renderWithDrawable drawWin $ do
region exposeRegion
clip
save
setOperator OperatorSource
setSourceRGBA 0 0 0 0
paint
restore
case background of
Nothing -> drawClockBackground False width height
Just background -> do
setSourceSurface background 0 0
paint
drawClockHands (isJust background) width height
case foreground of
Nothing -> drawClockForeground False width height
Just foreground -> do
setSourceSurface foreground 0 0
paint
return True
: 그러나
Cairo
액션의 수행 결과를 캐시하는 방법을 보여줍니다 gtk2hs에 포함 된 데모가, 특히 라인 320-404
main
의,
cairo/demo/Clock.hs 참조