finished coding merging functionality

fcore/quad-tree.sml

@@ -320,13 +320,12 @@ struct
 
   local
     fun loop (x, y, ex, ey, grid) =
-      if x > 0 then
+      if x < 0 then
-        if quadHasSameColour (x, y, ex, ey, grid) then
-          loop (x - 1, y, x, ey, grid)
-        else
-          ex
-      else
         0
+      else if quadHasSameColour (x, y, ex, ey, grid) then
+        loop (x - 1, y, x, ey, grid)
+      else
+        ex
   in
     fun getLeftmostX ({x, y, ex, ey, data}, grid) =
       loop (x - 1, y, x, ey, grid)
@@ -348,7 +347,7 @@ struct
 
   local
     fun loop (x, y, ex, ey, grid) =
-      if y = 0 orelse ey = 0 then
+      if y < 0 then
         0
       else if quadHasSameColour (x, y, ex, ey, grid) then
         loop (x, y - 1, ex, y, grid)
@@ -356,7 +355,7 @@ struct
         ey
   in
     fun getTopmostY ({x, y, ex, ey, data}, grid) =
-      if y <= 0 orelse ey <= 0 then
+      if y < 0 orelse ey <= 0 then
         0
       else if quadHasSameColour (x, y, ex, ey, grid) then
         loop (x, y - 1, ex, y, grid)
@@ -465,13 +464,14 @@ struct
   end
 
   fun merge (tree, grid) =
-    let val tree = mergeVertical (tree, grid)
+    let
-    in toBintree tree
+      val tree = mergeVertical (tree, grid)
+      val tree = mergeHorizontal (tree, grid)
+    in
+      toBintree tree
     end
 
-  (* temporarily shadow previous "toTriangles" function. 
+  fun toTrianglesMerged
-   * When this is done being implemented, rename to "toTrianglesCompressed" *)
-  fun toTriangles
     ( windowWidth
     , windowHeight
     , squares
@@ -483,17 +483,8 @@ struct
     ) =
     let
       val qtree = buildTree (0, 0, size, squares)
-      val bintree = toBintree qtree
       val bintree = merge (qtree, squares)
 
-      val list = BinTree.toList bintree
-      val length = List.length list
-      val _ = print ("length = " ^ Int.toString length ^ "\n")
-
-      val _ = print "start fold\n"
-      val _ = List.foldl (fn (item, _) => printItem item) () list
-      val _ = print "finish fold\n"
-
       val f = folder
         ( windowWidth
         , windowHeight