101 lines
2.8 KiB
Standard ML
101 lines
2.8 KiB
Standard ML
structure LayerTree =
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struct
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type square = {r: int, g: int, b: int, a: int}
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type grid = square vector vector
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datatype tree =
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NODE of {key: int, value: grid, left: tree, right: tree}
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| LEAF
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val emptyPixel = {r = 0, g = 0, b = 0, a = 0}
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val emptyTree = LEAF
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fun isBlank ({a, ...}: square) = a = 0
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fun insert (newKey, newValue, tree) =
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case tree of
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LEAF => NODE {key = newKey, value = newValue, left = LEAF, right = LEAF}
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| NODE {key, value, left, right} =>
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if newKey < key then
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let val left = insert (newKey, newValue, left)
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in NODE {key = key, value = value, left = left, right = right}
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end
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else if newKey > key then
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let val right = insert (newKey, newValue, right)
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in NODE {key = key, value = value, left = left, right = right}
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end
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else
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NODE {key = key, value = newValue, left = left, right = right}
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fun get (searchKey, tree) =
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case tree of
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LEAF => NONE
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| NODE {key, value, left, right} =>
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if searchKey < key then get (searchKey, left)
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else if searchKey > key then get (searchKey, right)
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else SOME value
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fun foldl (f, tree, acc) =
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case tree of
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LEAF => acc
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| NODE {value, left, right, ...} =>
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let
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val acc = foldl (f, left, acc)
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val acc = f (value, acc)
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in
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foldl (f, right, acc)
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end
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fun map (f, tree) =
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case tree of
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LEAF => LEAF
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| NODE {key, value, left, right} =>
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let
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val left = map (f, left)
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val right = map (f, right)
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val newValue = f value
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in
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NODE {key = key, value = value, left = left, right = right}
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end
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(* copies non-blank pixels in value vector into acc *)
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fun helpFlatten (value, acc) =
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Vector.mapi
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(fn (xIdx, valueYAxis) =>
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Vector.mapi
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(fn (yIdx, valuePixel) =>
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if isBlank valuePixel then
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let val accYAxis = Vector.sub (acc, xIdx)
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in Vector.sub (accYAxis, yIdx)
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end
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else
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valuePixel) valueYAxis) value
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fun makeEmptyGrid maxSide =
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Vector.tabulate (maxSide, fn _ =>
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Vector.tabulate (maxSide, fn _ => emptyPixel))
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fun flatten (maxSide, tree) =
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foldl (helpFlatten, tree, makeEmptyGrid maxSide)
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fun helpChangeGridSize maxSide squares =
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Vector.tabulate (maxSide, fn i =>
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if i < Vector.length squares then
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let
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val yAxis = Vector.sub (squares, i)
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in
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Vector.tabulate (maxSide, fn ii =>
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if ii < Vector.length yAxis then Vector.sub (yAxis, ii)
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else emptyPixel)
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end
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else
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Vector.tabulate (maxSide, fn _ => emptyPixel))
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fun changeGridSize (maxSide, tree) =
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let val f = helpChangeGridSize maxSide
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in map (f, tree)
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end
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end
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