用四叉树对图像分类，获取tag和key

function getMid(num) {
  if(num%2===0){
    return num/2
  }else{
    return (num+1)/2
  }

}
function getFourTree(rect,[x1,y1,x2,y2],deep) {
  if(deep===3){
    let num=0
    for(let y=y1;y<y2;y++){
      for(let x=x1;x<x2;x++){
        num+=rect.data[y*rect.width+x]
      }
    }
    return num;
  }
  if(x2-x1===1&&y2-y1===1){
    return {
      val:rect.data[y1*rect.width+x1]
    }
  }

  const mx=getMid(x1+x2)
  const my=getMid(y1+y2)
  const tree={
    val:0,
    child:[]
  }
  if(mx-x1>0&&my-y1>0){
    tree.child[0]=getFourTree(rect,[x1,y1,mx,my],deep+1)
    if(deep===2){
      tree.val+=tree.child[0];
    }else{
      tree.val+=tree.child[0].val;
    }

  }
  if(x2-mx>0&&my-y1>0){
    tree.child[1]=getFourTree(rect,[mx,y1,x2,my],deep+1)
    if(deep===2){
      tree.val+=tree.child[1];
    }else{
      tree.val+=tree.child[1].val;
    }
  }
  if(mx-x1>0&&y2-my>0){
    tree.child[2]=getFourTree(rect,[x1,my,mx,y2],deep+1)
    if(deep===2){
      tree.val+=tree.child[2];
    }else{
      tree.val+=tree.child[2].val;
    }
  }
  if(x2-mx>0&&y2-my>0){
    tree.child[3]=getFourTree(rect,[mx,my,x2,y2],deep+1)
    if(deep===2){
      tree.val+=tree.child[3];
    }else{
      tree.val+=tree.child[3].val;
    }
  }

  return tree
}
function getTagAndKey(rect1) {
  const tree=getFourTree(rect1,[0,0,rect1.width,rect1.height],0);
  console.log(tree)
  let tagArr=[];
  let keyArr=[];
  tree.child.forEach(function (child) {
    child.child.forEach(function (child2) {
      tagArr.push(child2.val * 4 >= child.val ? 1 : 0);
      child2.child.forEach(function (val) {
        keyArr.push(val * 4 >= child2.val ? 1 : 0);
      })
    })
  })
  return [tagArr.join(‘‘),keyArr.join(‘‘)]
}