Position and drag an item with a converted application

Question

Position and drag an item with a converted application

I have javascript code that works great for dragging an object ... but when I scaled the body to 0.5 ...

transform:scale(0.5);

mouse position and dragged object do not match. How can i fix this? or is it possible? ... thanks.

Here is the fiddle: http://jsfiddle.net/Xcb8d/65/

+4

javascript html css3 transform

user3204806 Apr 10 '14 at 0:45

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2 answers

cgatian · Answer 1 · 2014-04-10T02:28:18+0000

It was quite interesting and makes me rethink all the locations that I just used offsetHeight and offsetWidth, not knowing that if the conversion was applied to the element, these readonly properties in JavaScript would return incorrect.

"" - clientHeight/offsetHeight . , getBoundingClientRect(). , .

, Height , .

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CSS

html,
body {
  width:100%;
  height:100%;
}

.half-size
{
   transform:scale(0.5);
  -moz-transform:scale(0.5);
  -webkit-transform:scale(0.5);
}
.quarter-size
{
   transform:scale(0.25);
  -moz-transform:scale(0.25);
  -webkit-transform:scale(0.25);
}

#draggable-element {
  width:100px;
  height:100px;
  background-color:#666;
  color:white;
  padding:10px 12px;
  cursor:move;
  position:relative; /* important (all position that not `static`) */
  display:block;
}

JavaScript:

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

var elem_height = 0;
var elem_width = 0;

// 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;

    var boundingRectangle = selected.getBoundingClientRect();

    y_elem = (selected.offsetHeight - (boundingRectangle.bottom - boundingRectangle.top)) / 2;
    x_elem = (selected.offsetWidth - (boundingRectangle.right - boundingRectangle.left)) / 2

    half_elem_height = (boundingRectangle.bottom - boundingRectangle.top) / 2;
    half_elem_width = (boundingRectangle.right - boundingRectangle.left) /2;

    document.addEventListener('mousemove', _move_elem, false);
    document.addEventListener('mouseup', _destroy, false);    
};

// Will be called when user dragging an element
function _move_elem(e) 
{
  x_pos = e.clientX;
  y_pos = e.clientY;

  selected.style.left = ((x_pos - x_elem) - half_elem_width) + 'px';
  selected.style.top = ((y_pos - y_elem) - half_elem_height) + 'px';    
}
// Destroy the object when we are done and remove event binds
function _destroy() {
  selected = null;
  document.removeEventListener('mousemove', _move_elem);
  document.removeEventListener('mouseup', _destroy);
}

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

HTML:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body> 
<div id="draggable-element" class='half-size'>Drag me!</div>    
</body>
</html>

http://jsbin.com/moyadici/1/edit ( jsBin jsFiddle )

. , . "-". , , .

G-Cyr · Answer 2 · 2014-04-10T02:01:13+0000

, , , , ...

Firefox, pointer-events, , .

, .

scale(0.5) 100px, 50px .

- none reset . 50px, . 50px, . ( , .

, : transform-origin:top left;, .

Firefox: http://jsfiddle.net/Xcb8d/78/

Chrome: http://jsfiddle.net/Xcb8d/79/ ( )

, :)

, .

: http://css-tricks.com/get-value-of-css-rotation-through-javascript/

, , , script

. rookie: http://jsfiddle.net/Xcb8d/82/

ex:

// Will be called when user dragging an element
function _move_elem(e) {
var el = window.document.body;
var st = window.getComputedStyle(el, null);
var tr = st.getPropertyValue("transform") ;

var values = tr.split('(')[1];
    values = values.split(')')[0];
    values = values.split(',');

var a = values[0];
var b = values[1];
var c = values[2];
var d = values[3];
    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 / a) - x_elem) + 'px';
        selected.style.top = ((y_pos /  d) - y_elem) + 'px';
    }
}

Position and drag an item with a converted application

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