renderQt.sml

fun translate(Rect(l1, t1, r1, b1), Rect(l2, t2, r2, b2)) =
    Rect(abs(l1 - l2), abs(t1 - t2), abs(r1 - r2), abs(b1 - b2))

fun calculateRelativePosition(rt as Rect(l, t, r, b), offset) =
    let
        val width = r - l
        val height = t - b
        val Rect(x, y, _, _) = translate(rt, offset)
        val cx1 = Int.toString(width div 2 + x)
        val cx2 = Int.toString(height + y)
        val cy1 = Int.toString(height div 2 + y)
        val cy2 = Int.toString(width + x)
        val x = Int.toString(x)
        val y = Int.toString(y)
        val width = Int.toString(width)
        val height = Int.toString(height)
    in
        (x, y, width, height, cx1, cx2, cy1, cy2)
    end


fun renderRectangle(rt, offset, color) =
    let
        val (x, y, width, height, _, _, _, _) = calculateRelativePosition(rt, offset)
    in
        "<rect x='" ^ x ^ "' y='" ^ y ^ "' width='" ^ width ^ "' height='" ^ height ^ "' style='stroke-width: 1px; fill: none; stroke: " ^ color ^ ";'/>"
    end

fun renderRectangles([], offset) = ""
  | renderRectangles(first::rest, offset) = 
        renderRectangle(first, offset, "blue") ^ renderRectangles(rest, offset)


fun render'(EmptyQuadTree, _) = ""
  | render'(qt as Qt(e as Rect(l, t, r, b), h, v, q1, q2, q3, q4), offset) =
    let
        val (x, y, _, _, cx1, cx2, cy1, cy2) = calculateRelativePosition(e, offset)
    in
        renderRectangle(e, offset, "black")
        ^ "<line x1='" ^ cx1 ^ "' y1='" ^ y ^ "' x2='" ^ cx1 ^ "' y2='" ^ cx2 ^ "' style='stroke-width: 1px; stroke: black;'/>"
        ^ "<line x1='" ^ x ^ "' y1='" ^ cy1 ^ "' x2='" ^ cy2 ^ "' y2='" ^ cy1 ^ "' style='stroke-width: 1px; stroke: black;'/>"
        ^ renderRectangles(v, offset)
        ^ renderRectangles(h, offset)
        ^ render'(q1, offset)
        ^ render'(q2, offset)
        ^ render'(q3, offset)
        ^ render'(q4, offset)
    end

(*  render(qt)
    TYPE: quadtree -> string
    EXAMPLE: 
        val xxx = emptyQtree(Rect(~100, 100, 100, ~100));
        val xxx = insert(xxx, Rect(10, ~10, 30, ~25));

        render(xxx);

        val xxx2 = emptyQtree(Rect(~1000, 1000, 1000, ~1000));
        val xxx2 = insert(xxx2, Rect(10, ~10, 30, ~25));
        val xxx2 = insert(xxx2, Rect(~90, ~30, ~10, ~400));
        val xxx2 = insert(xxx2, Rect(100, 250, 300, 10));

        render(xxx2);
*)
fun render(qt as Qt(Rect(l, t, r, b), _, _, _, _, _, _)) =
    let
        val width = Int.toString(r - l)
        val height = Int.toString(t - b)
        val offset = Rect(l, t, 0, 0)
    in
            "<svg xmlns='http://www.w3.org/2000/svg' width='" ^ width ^ "' height='" ^ height ^ "'>"
        ^       render'(qt, offset)
        ^   "</svg>"
    end

(*  renderToFile(qt, name)
    TYPE: quadtree * string -> unit
    EXAMPLE: 
        val xxx = emptyQtree(Rect(~100, 100, 100, ~100));
        val xxx = insert(xxx, Rect(10, ~10, 30, ~25));

        renderToFile(xxx, "test.svg");

        val xxx2 = emptyQtree(Rect(~1000, 1000, 1000, ~1000));
        val xxx2 = insert(xxx2, Rect(10, ~10, 30, ~25));
        val xxx2 = insert(xxx2, Rect(~90, ~30, ~10, ~400));
        val xxx2 = insert(xxx2, Rect(100, 250, 300, 10));

        renderToFile(xxx2, "test2.svg");
*)
fun renderToFile(qt, name) =
    let
        val h = TextIO.openOut name
    in
        TextIO.outputSubstr(h, Substring.full(render(qt)));
        TextIO.flushOut(h)
    end
;