#18 Optimes rendering by caching PNGs

lib/SelectorRenderer.hs

@@ -0,0 +1,39 @@
+module SelectorRenderer
+( renderSelector
+, renderSelected
+) where
+
+import Selector
+import PNGRenderer
+
+----------------------------- Constants ------------------------------
+
+selectorFilePath :: FilePath
+selectorFilePath = "./lib/assets/selector.png"
+
+selectedFilePath :: FilePath
+selectedFilePath = "./lib/assets/selected.png"
+
+selectorRenders :: (Picture, Picture)
+selectorRenders = (
+    renderPNG selectorFilePath, 
+    renderPNG selectedFilePath
+    )
+
+----------------------------------------------------------------------
+
+-- Render the outline of the selector. The offset for every value 1 
+-- in the coordinate must be given.
+renderSelector :: Float -> Float -> Selector -> Picture
+renderSelector a b Selector{ position = (x,y) } = translate fx fy render
+    where fx     = fromIntegral x * a
+          fy     = fromIntegral y * b
+          render = fst selectorRenders
+
+-- Render the selected piece if any.
+renderSelected :: Float -> Float -> Selector -> Picture
+renderSelected a b Selector{ selected = Just (x, y) } = translate fx fy render
+    where fx     = fromIntegral x * a
+          fy     = fromIntegral y * b
+          render = snd selectorRenders
+renderSelected _ _ _                                  = blank