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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              html, body
  height: 100%
  
svg
  border: 1px solid black
  background: white
  
            
          
!
            
              class Rectangle {
  constructor(x, y, width, height) {
    this.x = x;
    this.y = y;
    this.width = width;
    this.height = height;
  }

  get right() {
    return this.x + this.width;
  }

  get top() {
    return this.y + this.height;
  }

  get bottom() {
    return this.y;
  }

  get left() {
    return this.x;
  }

  get midPoint() {
    return {
      x: this.x + this.width / 2,
      y: this.y + this.height / 2
    };
  }

  overlaps(rect) {
    return (
      this.left < rect.right &&
      this.right > rect.left &&
      this.top > rect.bottom &&
      this.bottom < rect.top
    );
  }

  containsRectangle(rect) {
    return (
      this.left <= rect.left &&
      this.right >= rect.right &&
      this.top >= rect.top &&
      this.bottom <= rect.bottom
    );
  }

  containsPoint(x, y) {
    return !(
      x < this.left ||
      y > this.top ||
      x > this.right ||
      y < this.bottom
    );
  }
}

class LinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.count = 0;
  }

  get length() {
    return this.count;
  }

  clear() {
    this.count = 0;
    this.head = null;
    this.tail = null;
  }

  add(data) {
    const node = {
      data: data,
      next: null
    };

    if (this.count === 0) {
      this.tail = node;
    } else {
      this.head.next = node;
    }
    this.head = node;
    this.count++;
  }
  
  // todo: just redirect the list
  addAll(list) {
    let curNode = list.tail;
    while (curnode != null) {
      this.add(curNode.data);
      curNode = curNode.next;
    }
  }
  
  get(target) {
    let curNode = this.tail;
    for (let i = 0; i < target; i++) {
      curNode = curNode.next;
    }
    return curNode.data;
  }

  remove(target) {
    this.count--;
    let prevNode = null;
    let deletedNode = this.tail;
    
    if (target === 0) {
      deletedNode = this.tail;
      this.tail = this.tail.next || null;
    } else {    
      for (let i = 0; i < target; i++) {
        prevNode = deletedNode;
        deletedNode = deletedNode.next;
      } 

      if (target === this.count) {
          this.head = prevNode;
      }
    }
  
    if (this.count === 0) {
      this.tail = null;
      this.head = null;
    }

    
    return deletedNode.data;
  }
}

class QuadTree {
  constructor(level, bounds) {
    this.level = level;
    this.bounds = bounds;
    this.maxLevels = 5;
    this.maxObjects = 5;
    this.objects = new LinkedList();
    this.nodes = new Array(4).fill(null);
  }

  insert(rect) {
    if (this.nodes[0] !== null) {
      let index = this._getQuadrantIndex(rect);
      console.log('placed into: ', index)
      if (index != -1) {
        this.nodes[index].insert(rect);
      }
    }

    this.objects.add(rect);

    if (this.objects.length > this.maxObjects && this.level < this.maxLevels) {
      if (this.nodes[0] === null) {
        this.split();
        console.log('split')
      }
      
      let i = 0;
      while (i < this.objects.length) {
        let index = this._getQuadrantIndex(this.objects.get(i));
        if (index != -1) {
          console.log('placed into: ', index)
          this.nodes[index].insert(this.objects.remove(i));
        } else {
          i++;
        }
      }
    }
  }
  
  retreive(objectList, rect) {
    let index = getIndex(rect);
    if (index != -1 && nodes[0] != null) {
      nodes[index].retrieve(objects, rect);
    }
    
    objectList.addAll(this.objects);
    
    return objectList;
  }

  split() {
    const quadrant = this._getQuadrants();    
    const level = this.level;
    this.nodes[0] = new QuadTree(level + 1, quadrant.bottomRight);
    this.nodes[1] = new QuadTree(level + 1, quadrant.bottomLeft);
    this.nodes[2] = new QuadTree(level + 1, quadrant.topLeft);
    this.nodes[3] = new QuadTree(level + 1, quadrant.topRight);
  }

  clear() {
    this.objects.clear();

    for (let i = 0; i < nodes.length; i++) {
      if (nodes[i] != null) {
        nodes[i].clear();
        nodes[i] = null;
      }
    }
  }

  _getQuadrants() {
    if (this.quadrants) {
      return this.quadrants;
    }

    const { x, y, width, height } = this.bounds;
    const { x: midX, y: midY } = this.bounds.midPoint;

    this.quadrants = {
      bottomRight: new Rectangle(midX, y, width/2, height/2),
      bottomLeft: new Rectangle(x, y,  width/2, height/2),
      topLeft: new Rectangle(x, midY,  width/2, height/2),
      topRight: new Rectangle(midX, midY, width/2, height/2),
    };

    return this.quadrants;
  }

  // Gets the quadrant index of the given rectangle, or in otherwords figures out if one of hte quadrants can completly contain the given rectangles
  _getQuadrantIndex(rect) {
    const quadrant = this._getQuadrants();
    if (quadrant.bottomRight.containsRectangle(rect)) {
      return 0;
    }
    if (quadrant.bottomLeft.containsRectangle(rect)) {
      return 1;
    }
    if (quadrant.topLeft.containsRectangle(rect)) {
      return 2;
    }
    if (quadrant.topRight.containsRectangle(rect)) {
      return 3;
    }
    return -1;
  }
}


const SvgRectangleComponent = props => {
  return <rect {...props}  />;
} 

const QuadTreeComponent = ({ width, height, quadtree }) => {
  let ck = 0;
  let cb = 1000;
  let nodes = [quadtree];
  let components = [];

  while (nodes.length > 0) {
    let curTree = nodes.shift();
    for (let i = 0; i < curTree.objects.length; i++) {
      let curObject = curTree.objects.get(i)
      components.push(
              <SvgRectangleComponent key={cb++} 
          x={curObject.x} 
          y={curObject.y} 
          width={curObject.width} 
          height={curObject.height} 
          style={{ fill: "rgb(0,0,200)", fillOpacity: "0.7" }}
          />)
    }
    if (curTree.nodes[0] === null) {
      
      let curBounds = curTree.bounds;      
      components.push(
        <SvgRectangleComponent key={ck++} 
          x={curBounds.x} 
          y={curBounds.y} 
          width={curBounds.width} 
          height={curBounds.height} 
          style={{ strokeWidth:"3", stroke:"rgb(255,0,0)", fill: "ffffff", fillOpacity: "0" }}
          />
      );
    } else {
      nodes = [...nodes, ...curTree.nodes];
    }
  }

  return (
    <svg width={width} height={height}>
      {components}
    </svg>
  );
};

function getRandomInt(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min)) + min; //The maximum is exclusive and the minimum is inclusive
}

function weightedRand2(spec) {
  var i, sum=0, r=Math.random();
  for (i in spec) {
    sum += spec[i];
    if (r <= sum) return i;
  }
}
  
class App extends React.Component {
  constructor(props) {
    super(props);
    this.bounds = new Rectangle(props.x,props.y,props.width,props.height);
    this.quadtree = new QuadTree(0,this.bounds);
    for (let i = 0; i < 125; i++) {
      // let x = getRandomInt(1, props.width - 10);
      let y = getRandomInt(1, props.height - 10);
      let x = getRandomInt(1,props.width / weightedRand2({3:0.5, 2:0.3, 1:0.2}));
      // let y = props.height / weightedRand2({1:0.7, 2:0.2, 3:0.1});
      this.quadtree.insert(new Rectangle(x, y, getRandomInt(5,20), getRandomInt(5,20)));
    }
  }

  render() {
    return (
      <div>
        <QuadTreeComponent {...this.props} quadtree={this.quadtree} />
      </div>
    );
  }
}

ReactDOM.render(<App x={0} y={0} width={600} height={600} />, document.getElementById("app"));

            
          
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