分别拖动每个元素

Question

我在像Win7 Sidebar这样的javascript中制作小工具系统，但我只能使用一个元素。如果我使用两个，所有元素可以具有相同的位置或不起作用。我需要可以使用多个元素并分别拖动每个元素（每个元素都有他的特定位置）。

我只有一个元素。如何将其与多个一起使用？

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var selected = null, // Object of the element to be moved
    x_pos = 0, y_pos = 0, // Stores x & y coordinates of the mouse pointer
    x_elem = 0, y_elem = 0; // Stores top, left values (edge) of the element

// Will be called when user starts dragging an element
function _drag_init(elem) {
    // Store the object of the element which needs to be moved
    selected = elem;
    x_elem = x_pos - selected.offsetLeft;
    y_elem = y_pos - selected.offsetTop;
}

// Will be called when user dragging an element
function _move_elem(e) {
    x_pos = document.all ? window.event.clientX : e.pageX;
    y_pos = document.all ? window.event.clientY : e.pageY;
    if (selected !== null) {
        selected.style.left = (x_pos - x_elem) + 'px';
        selected.style.top = (y_pos - y_elem) + 'px';
    }
}

// Destroy the object when we are done
function _destroy() {
    selected = null;
}

// Bind the functions...
document.getElementById('draggable-element').onmousedown = function () {
    _drag_init(this);
    return false;
};

document.onmousemove = _move_elem;
document.onmouseup = _destroy;

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body {padding:10px}

#draggable-element {
  width:125px;
  height:125px;
  background-color:#666;
  color:white;
  padding:10px 12px;
  cursor:move;
  position:relative; /* important (all position that's not `static`) */
}

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<div id="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>

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fiddle

Answer 1

有两点需要注意：

1. 如果您想对多个元素执行某些操作，则需要使用class或tag s。
2. 在_drag_init()功能中，您将x_elem和y_elem设置为x_pos和y_pos，这些更改在您_move_elem()功能中。因此它将当前定位添加到元素偏移量中。所以只需摆脱selected.Offset

但是，您还需要解决其他一些计算问题

var selected = null, // Object of the element to be moved
    x_pos = 0, y_pos = 0, // Stores x & y coordinates of the mouse pointer
    x_elem = 0, y_elem = 0; // Stores top, left values (edge) of the element

// Will be called when user starts dragging an element
function _drag_init(elem) {
    // Store the object of the element which needs to be moved
    selected = elem;
    x_elem = x_pos ;
    y_elem = y_pos;
}

// Will be called when user dragging an element
function _move_elem(e) {
    x_pos = document.all ? window.event.clientX : e.pageX;
    y_pos = document.all ? window.event.clientY : e.pageY;
    if (selected !== null) {
        selected.style.left = (x_pos - x_elem) + 'px';
        selected.style.top = (y_pos - y_elem) + 'px';
    }
}

// Destroy the object when we are done
function _destroy() {
    selected = null;
}

// Bind the functions...
var draggables = document.getElementsByClassName('draggable-element');
for(var i = 0; i < draggables.length; i++){
  draggables[i].onmousedown = function () {
      _drag_init(this);
      return false;
  };
}

document.onmousemove = _move_elem;
document.onmouseup = _destroy;

body {padding:10px}

.draggable-element {
  width:125px;
  height:125px;
  background-color:#666;
  color:white;
  padding:10px 12px;
  cursor:move;
  position:relative; /* important (all position that's not `static`) */
}

<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>
<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>
<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>
<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>
<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>
<div class="draggable-element">Gadget!<div style="width:20px;height:100%;background:#000;position:absolute;top:0;right:-25px"></div></div>