fix bugs with generating export strings from quad tree (have to add 1 to ex and ey indiscriminately, except if we are not in the canvas width/height dimensions)

fcore/quad-tree.sml

@@ -534,14 +534,15 @@ struct
     in "endYToNdc (yOffset, " ^ startY ^ ", " ^ endY ^ ", scale, halfHeight)"
     end
 
-  fun toExportStringFolder ({x, ex, y, ey, data = {r, g, b, a}}, acc) =
+  fun toExportStringFolder (maxWidth, maxHeight) ({x, ex, y, ey, data = {r, g, b, a}}, acc) =
     let
-      val ey = if ey = y then y + 1 else ey
+      val ex = if ex < maxWidth then ex + 1 else ex
+      val ey = if ey < maxHeight then ey + 1 else ey
 
       val x = makeXString x
       val y = makeYString y
       val ex = makeEndXString (x, ex)
-      val ey = makeYString ey
+      val ey = makeEndYString (y, ey)
       val r = colToRealString r
       val g = colToRealString g
       val b = colToRealString b
@@ -589,7 +590,8 @@ struct
       val qtree = buildTree (0, 0, size, squares)
       val bintree = merge (qtree, squares)
 
-      val coords = BinTree.foldr (toExportStringFolder, bintree, [])
+      val f = toExportStringFolder (canvasWidth, canvasHeight)
+      val coords = BinTree.foldr (f, bintree, [])
       val coords = String.concatWith ",\n" coords
     in
       String.concat
@@ -630,10 +632,10 @@ struct
   fun mapGrid grid =
     Vector.map (fn yAxis => Vector.map (fn item => mapItem item) yAxis) grid
 
-  fun toCollisionStringFolder scale ({x, ex, y, ey, data = _}, acc) =
+  fun toCollisionStringFolder (scale, maxWidth, maxHeight) ({x, ex, y, ey, data = _}, acc) =
     let
-      val ex = ex + 1
-      val ey = if y = ey then ey + 1 else ey
+      val ex = if ex < maxWidth then ex + 1 else ex
+      val ey = if ey < maxHeight then ey + 1 else ey
 
       val width = ex - x
       val width = if width = 0 then width + 1 else width
@@ -662,11 +664,12 @@ struct
 
   fun toCollisionString (squares, canvasWidth, canvasHeight, scale) =
     let
+      val scale = if scale = 0 then 1 else scale
       val size = Int.max (canvasWidth, canvasHeight)
       val qtree = buildTree (0, 0, size, squares)
       val bintree = merge (qtree, squares)
 
-      val f = toCollisionStringFolder scale
+      val f = toCollisionStringFolder (scale, canvasWidth, canvasHeight)
       val collisions = BinTree.foldr (f, bintree, [])
       val collisions = String.concatWith ",\n" collisions
     in