Allow dragging of selected items in inventory

src/Dodge/SelectionSections.hs

@@ -9,6 +9,8 @@ module Dodge.SelectionSections (
     inverseSelSecYint,
     posSelSecYint,
     inverseSelNumPos,
+    inverseSelBoundaryUp,
+    inverseSelBoundaryDown,
 ) where
 
 import Control.Monad
@@ -186,5 +188,32 @@ inverseSelNumPos ::
 inverseSelNumPos cfig ldp sss (V2 x y) =
     inverseSelSecYintXPosCheck cfig ldp x (posSelSecYint cfig ldp y) sss
 
+inverseSelBoundaryUp :: 
+    Configuration ->
+    ListDisplayParams ->
+    SelectionSections a ->
+    Point2 ->
+    Maybe (Int,Int)
+inverseSelBoundaryUp cfig ldp sss (V2 _ y)  = do
+    sel <- inverseSelSecYint (posSelSecYint cfig ldp y) sss
+    let mselup = inverseSelSecYint (posSelSecYint cfig ldp y - 1) sss
+    if Just sel == mselup
+        then return $ sel & _2 +~ 1
+        else return $ sel
+
+inverseSelBoundaryDown :: 
+    Configuration ->
+    ListDisplayParams ->
+    SelectionSections a ->
+    Point2 ->
+    Maybe (Int,Int)
+inverseSelBoundaryDown cfig ldp sss (V2 _ y)  = do
+    sel <- inverseSelSecYint (posSelSecYint cfig ldp y) sss
+    let mseldown = inverseSelSecYint (posSelSecYint cfig ldp y + 1) sss
+    if Just sel == mseldown
+        then return $ sel & _2 -~ 1
+        else return sel
+
+
 --getIthPos :: Int -> IM.IntMap (SelectionItem a) -> Int
 --getIthPos i sm = sum . fmap _siHeight . fst $ IM.split i sm