如何从各个角度调整大小的div？

Question

我正在创建一个可拖动且可调整大小的div。可拖动的设备正常工作。我希望div在单击位于所有角落的“调整大小”之后，可以使用移动鼠标更改宽度和高度。我想出了如何做右下角的“调整大小”，它工作正常，但我不能做左下角。有谁知道如何？

window.addEventListener('mouseup', mouseUpDragElement, false);
document.getElementById("dragdiv").addEventListener('mousedown', mouseDownDragElement, false);
document.getElementById("dragdiv").addEventListener('mousedown', mouseDownResizeElement, false);

var elementdragTop;
var elementdragLeft;

function mouseDownDragElement(e) {
  window.addEventListener("mousemove", myFunctionDragElement, true);
  elementdragTop = e.clientX - document.getElementById("dragdiv").offsetLeft;
  elementdragLeft = e.clientY - document.getElementById("dragdiv").offsetTop;
}

function mouseUpDragElement() {
  window.removeEventListener("mousemove", myFunctionDragElement, true);
}

function myFunctionDragElement(e) {

  var x = e.clientX;
  var y = e.clientY;

  document.getElementById("dragdiv").style.position = "absolute";
  document.getElementById("dragdiv").style.left = (x - elementdragTop) + 'px';
  document.getElementById("dragdiv").style.top = (y - elementdragLeft) + 'px';

}

function mouseDownResizeElement(e) {
  var resizertopleft = document.createElement("DIV");
  resizertopleft.id = "resizer-top-left";
  document.getElementById("dragdiv").appendChild(resizertopleft);

  var resizertopright = document.createElement("DIV");
  resizertopright.id = "resizer-top-right";
  document.getElementById("dragdiv").appendChild(resizertopright);

  var resizerbottomleft = document.createElement("DIV");
  resizerbottomleft.id = "resizer-bottom-left";
  resizerbottomleft.addEventListener('mousedown', mouseDownResizeElementResizerBottomLeft, false);
  document.getElementById("dragdiv").appendChild(resizerbottomleft);

  var resizerbottomright = document.createElement("DIV");
  resizerbottomright.id = "resizer-bottom-right";
  resizerbottomright.addEventListener('mousedown', mouseDownResizeElementResizerBottomRight, false);
  document.getElementById("dragdiv").appendChild(resizerbottomright);


}

function mouseUpResizeElement(e) {
  document.getElementById("resizer-top-left").remove();
}

// BUTTON BOTTOM RIGHT

function mouseDownResizeElementResizerBottomRight() {
  window.addEventListener("mousemove", mouseMoveResizeElementResizerBottomRight, true);
  document.getElementById("dragdiv").addEventListener('mouseup', mouseUpResizeElementResizerBottomRight, true);

}

function mouseMoveResizeElementResizerBottomRight(e) {
  document.getElementById("dragdiv").addEventListener('mouseup', mouseUpResizeElementResizerBottomRight, true);
  window.removeEventListener("mousemove", myFunctionDragElement, true);

  document.getElementById("dragdiv").style.width = e.pageX - document.getElementById("dragdiv").getBoundingClientRect().left + 'px';
  document.getElementById("dragdiv").style.height = e.pageY - document.getElementById("dragdiv").getBoundingClientRect().top + 'px';

}

function mouseUpResizeElementResizerBottomRight() {
  window.removeEventListener("mousemove", mouseMoveResizeElementResizerBottomRight, true);


}

// BUTTON BOTTOM LEFT ???  Here is the code that does not work

function mouseDownResizeElementResizerBottomLeft(e) {
  window.addEventListener("mousemove", mouseMoveResizeElementResizerBottomLeft, true);
  document.getElementById("dragdiv").addEventListener('mouseup', mouseUpResizeElementResizerBottomLeft, true);
  originaldivwidth = document.getElementById("dragdiv").style.width;
  originaldivleft = document.getElementById("dragdiv").getBoundingClientRect().left;
  originaldivright = document.getElementById("dragdiv").getBoundingClientRect().right;
  originalmousex = e.clientX;
}

function mouseMoveResizeElementResizerBottomLeft(e) {
  document.getElementById("dragdiv").addEventListener('mouseup', mouseUpResizeElementResizerBottomLeft, true);
  window.removeEventListener("mousemove", myFunctionDragElement, true);

  var elementoriginalwidth = document.getElementById("dragdiv").style.width;
  var elementoriginalleft = document.getElementById("dragdiv").getBoundingClientRect().left;
  var mouseX = e.clientX;



  document.getElementById("dragdiv").style.width = document.getElementById("dragdiv").style.width + (e.clientX - originalmousex) + 'px';
  document.getElementById("dragdiv").style.left = e.clientX + (e.clientX - originalmousex) + 'px';


}

function mouseUpResizeElementResizerBottomLeft() {
  window.removeEventListener("mousemove", mouseMoveResizeElementResizerBottomLeft, true);


}

#dragdiv {
  width: 100px;
  height: 100px;
  background-color: red;
  position: absolute;
  margin: 0px;
}

#resizer-top-left {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: white;
  border: 3px solid #4286f4;
  position: absolute;
  left: -5px;
  top: -5px;
  cursor: nwse-resize;
}

#resizer-top-right {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: white;
  border: 3px solid #4286f4;
  position: absolute;
  right: -5px;
  top: -5px;
  cursor: nesw-resize;
}

#resizer-bottom-left {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: white;
  border: 3px solid #4286f4;
  position: absolute;
  left: -5px;
  bottom: -5px;
  cursor: nesw-resize;
}

#resizer-bottom-right {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: white;
  border: 3px solid #4286f4;
  position: absolute;
  right: -5px;
  bottom: -5px;
  cursor: nwse-resize;
}

<div id="container">
  <div id="dragdiv"></div>
</div>

Answer 1

HTML

<div class='resizable'>
  <div class='resizers'>
    <div class='resizer top-left'></div>
    <div class='resizer top-right'></div>
    <div class='resizer bottom-left'></div>
    <div class='resizer bottom-right'></div>
  </div>
</div>

CSS

body,
html {
  background: black;
}
.resizable {
  background: white;
  width: 100px;
  height: 100px;
  position: absolute;
  top: 100px;
  left: 100px;
}

.resizable .resizers{
  width: 100%;
  height: 100%;
  border: 3px solid #4286f4;
  box-sizing: border-box;
}

.resizable .resizers .resizer{
  width: 10px;
  height: 10px;
  border-radius: 50%; /*magic to turn square into circle*/
  background: white;
  border: 3px solid #4286f4;
  position: absolute;
}

.resizable .resizers .resizer.top-left {
  left: -5px;
  top: -5px;
  cursor: nwse-resize; /*resizer cursor*/
}
.resizable .resizers .resizer.top-right {
  right: -5px;
  top: -5px;
  cursor: nesw-resize;
}
.resizable .resizers .resizer.bottom-left {
  left: -5px;
  bottom: -5px;
  cursor: nesw-resize;
}
.resizable .resizers .resizer.bottom-right {
  right: -5px;
  bottom: -5px;
  cursor: nwse-resize;
}

JS

function makeResizableDiv(div) {
  const element = document.querySelector(div);
  const resizers = document.querySelectorAll(div + ' .resizer')
  const minimum_size = 20;
  let original_width = 0;
  let original_height = 0;
  let original_x = 0;
  let original_y = 0;
  let original_mouse_x = 0;
  let original_mouse_y = 0;
  for (let i = 0;i < resizers.length; i++) {
    const currentResizer = resizers[i];
    currentResizer.addEventListener('mousedown', function(e) {
      e.preventDefault()
      original_width = parseFloat(getComputedStyle(element, null).getPropertyValue('width').replace('px', ''));
      original_height = parseFloat(getComputedStyle(element, null).getPropertyValue('height').replace('px', ''));
      original_x = element.getBoundingClientRect().left;
      original_y = element.getBoundingClientRect().top;
      original_mouse_x = e.pageX;
      original_mouse_y = e.pageY;
      window.addEventListener('mousemove', resize)
      window.addEventListener('mouseup', stopResize)
    })

    function resize(e) {
      if (currentResizer.classList.contains('bottom-right')) {
        const width = original_width + (e.pageX - original_mouse_x);
        const height = original_height + (e.pageY - original_mouse_y)
        if (width > minimum_size) {
          element.style.width = width + 'px'
        }
        if (height > minimum_size) {
          element.style.height = height + 'px'
        }
      }
      else if (currentResizer.classList.contains('bottom-left')) {
        const height = original_height + (e.pageY - original_mouse_y)
        const width = original_width - (e.pageX - original_mouse_x)
        if (height > minimum_size) {
          element.style.height = height + 'px'
        }
        if (width > minimum_size) {
          element.style.width = width + 'px'
          element.style.left = original_x + (e.pageX - original_mouse_x) + 'px'
        }
      }
      else if (currentResizer.classList.contains('top-right')) {
        const width = original_width + (e.pageX - original_mouse_x)
        const height = original_height - (e.pageY - original_mouse_y)
        if (width > minimum_size) {
          element.style.width = width + 'px'
        }
        if (height > minimum_size) {
          element.style.height = height + 'px'
          element.style.top = original_y + (e.pageY - original_mouse_y) + 'px'
        }
      }
      else {
        const width = original_width - (e.pageX - original_mouse_x)
        const height = original_height - (e.pageY - original_mouse_y)
        if (width > minimum_size) {
          element.style.width = width + 'px'
          element.style.left = original_x + (e.pageX - original_mouse_x) + 'px'
        }
        if (height > minimum_size) {
          element.style.height = height + 'px'
          element.style.top = original_y + (e.pageY - original_mouse_y) + 'px'
        }
      }
    }

    function stopResize() {
      window.removeEventListener('mousemove', resize)
    }
  }
}

makeResizableDiv('.resizable')

来源：https://codepen.io/ZeroX-DG/pen/vjdoYe