fix loading to use and return layer tree

fcore/normal-mode.sml

@@ -134,36 +134,25 @@ struct
 
   fun realToInt x = Real32.toInt IEEEReal.TO_NEAREST x
 
-  fun changePixel (model: app_type, hIdx, vIdx, pixel) =
+  fun getDrawMessage (model: app_type) =
     let
       val
-        { windowWidth
+        { canvasWidth
+        , canvasHeight
+        , layerTree
+        , windowWidth
         , windowHeight
         , xClickPoints
         , yClickPoints
-        , canvasWidth
-        , canvasHeight
-        , layer
-        , layerTree
-        , r
-        , g
-        , b
-        , a
+        , arrowX
+        , arrowY
         , ...
         } = model
 
       val maxSide = Int.max (canvasWidth, canvasHeight)
-
-      val xpos = Vector.sub (xClickPoints, hIdx)
-      val ypos = Vector.sub (yClickPoints, vIdx)
-
-      val layerTree = LayerTree.addPixel
-        (layer, hIdx, vIdx, maxSide, pixel, layerTree)
-      val model = AppWith.layerTree (model, layerTree, hIdx, vIdx)
-
       val squares = LayerTree.flatten (maxSide, layerTree)
 
-      val dotVec = getDotVecFromIndices (model, hIdx, vIdx)
+      val dotVec = getDotVecFromIndices (model, arrowX, arrowY)
 
       val squares = CollisionTree.toTriangles
         ( windowWidth
@@ -180,6 +169,19 @@ struct
       (model, [DRAW drawMsg])
     end
 
+  fun changePixel (model: app_type, hIdx, vIdx, pixel) =
+    let
+      val {canvasWidth, canvasHeight, layer, layerTree, ...} = model
+
+      val maxSide = Int.max (canvasWidth, canvasHeight)
+
+      val layerTree = LayerTree.addPixel
+        (layer, hIdx, vIdx, maxSide, pixel, layerTree)
+      val model = AppWith.layerTree (model, layerTree, hIdx, vIdx)
+    in
+      getDrawMessage model
+    end
+
   fun addPixel (model: app_type, hIdx, vIdx) =
     let
       val {r, g, b, a, ...} = model
@@ -332,8 +334,13 @@ struct
       updateCanvas (model, canvasWidth, canvasHeight)
     end
 
-  fun useSquares (model, squares, canvasWidth, canvasHeight) =
-    raise Fail "todo: reimplement"
+  fun useLayers (model, layerTree, canvasWidth, canvasHeight) =
+    let
+      val model =
+        AppWith.layerTree (model, layerTree, canvasWidth, canvasHeight)
+    in
+      getDrawMessage model
+    end
 
   fun enterBrowseMode model =
     let
@@ -382,8 +389,8 @@ struct
     | KEY_CTRL_L => CommonUpdate.getLoadSquaresMsg model
     | KEY_CTRL_E => CommonUpdate.getExportSquaresMsg model
     | KEY_CTRL_C => CommonUpdate.getCollisionMsg model
-    | USE_SQUARES {squares, canvasWidth, canvasHeight} =>
-        useSquares (model, squares, canvasWidth, canvasHeight)
+    | USE_LAYERS {tree, canvasWidth, canvasHeight} =>
+        useLayers (model, tree, canvasWidth, canvasHeight)
     | SQUARES_LOAD_ERROR => CommonUpdate.squaresLoadError model
     | KEY_CTRL_O => enterBrowseMode model
     | ARROW_UP => moveArrowUp model