pub/graphlib/lib/src/layout/charted/intersect/rect.dart

library graphlib.layout.charted.intersect.rect;

intersectRect(node, point) {
  var x = node.x;
  var y = node.y;

  // Rectangle intersection algorithm from:
  // http://math.stackexchange.com/questions/108113/find-edge-between-two-boxes
  var dx = point.x - x;
  var dy = point.y - y;
  var w = node.width / 2;
  var h = node.height / 2;

  var sx, sy;
  if (dy.abs() * w > dx.abs() * h) {
    // Intersection is top or bottom of rect.
    if (dy < 0) {
      h = -h;
    }
    sx = dy == 0 ? 0 : h * dx / dy;
    sy = h;
  } else {
    // Intersection is left or right of rect.
    if (dx < 0) {
      w = -w;
    }
    sx = w;
    sy = dx == 0 ? 0 : w * dy / dx;
  }

  return {"x": x + sx, "y": y + sy};
}