Merge pull request #307 from phsmenon/fix-cache-clickables

Include clickable elements in the rendering cache.

src/Brick/Types/Internal.hs

@@ -249,7 +249,7 @@ data RenderState n =
     RS { viewportMap :: !(M.Map n Viewport)
        , rsScrollRequests :: ![(n, ScrollRequest)]
        , observedNames :: !(S.Set n)
-       , renderCache :: !(M.Map n (Result n))
+       , renderCache :: !(M.Map n ([n], Result n))
        , clickableNames :: ![n]
        } deriving (Read, Show, Generic, NFData)
 

src/Brick/Widgets/Core.hs

@@ -962,24 +962,40 @@ vRelease p =
 -- use the rendered version from the cache. If not, render the specified
 -- widget and update the cache with the result.
 --
+-- To ensure that mouse events are emitted correctly for cached widgets, 
+-- in addition to the rendered widget, we also cache (the names of) 
+-- any clickable extents that were rendered and restore that when utilizing
+-- the cache.
+--
 -- See also 'invalidateCacheEntry'.
 cached :: (Ord n) => n -> Widget n -> Widget n
 cached n w =
     Widget (hSize w) (vSize w) $ do
         result <- cacheLookup n
         case result of
-            Just prevResult -> return prevResult
+            Just (clickables, prevResult) -> do
+                clickableNamesL %= (clickables ++)
+                return prevResult
             Nothing  -> do
                 wResult <- render w
-                cacheUpdate n wResult
+                clickables <- renderedClickables wResult
+                cacheUpdate n (clickables, wResult)
                 return wResult
+    where
+        -- Given the rendered result of a Widget, collect the list of "clickable" names
+        -- from the extents that were in the result.
+        renderedClickables :: (Ord n) => Result n -> RenderM n [n]
+        renderedClickables renderResult = do
+            allClickables <- use clickableNamesL
+            return [extentName e | e <- renderResult^.extentsL, extentName e `elem` allClickables]
 
-cacheLookup :: (Ord n) => n -> RenderM n (Maybe (Result n))
+
+cacheLookup :: (Ord n) => n -> RenderM n (Maybe ([n], Result n))
 cacheLookup n = do
     cache <- lift $ gets (^.renderCacheL)
     return $ M.lookup n cache
 
-cacheUpdate :: (Ord n) => n -> Result n -> RenderM n ()
+cacheUpdate :: (Ord n) => n -> ([n], Result n) -> RenderM n ()
 cacheUpdate n r = lift $ modify (& renderCacheL %~ M.insert n r)
 
 -- | Render the specified widget in a named viewport with the