我破解了它:)
小提琴(和 CSS):http: //jsfiddle.net/jhogervorst/CPA5Y/
HTML:
<div class="group">
<h1>Group 1</h1>
<ul class="parent">
<li class="droppable"><span class="draggable">Item 1</span></li>
<li class="droppable"><span class="draggable">Item 2</span></li>
<li class="droppable"></li>
</ul>
</div>
<div class="group">
<h1>Group 2</h1>
<ul class="parent">
<li class="droppable"><span class="draggable">Item 3</span></li>
<li class="droppable"></li>
<li class="droppable"><span class="draggable">Item 4</span></li>
</ul>
</div>
JavaScript:
$(".draggable").draggable({
revert: true,
revertDuration: 0
});
$(".droppable").droppable({
activeClass: "active",
hoverClass: "hover",
accept: function (draggable) {
// The droppable (li element).
var droppable = $(this);
// The droppable which contains the draggable, i.e., the parent element of the draggable (li element).
var draggablesDropable = draggable.parent();
// Is the draggable being dragged/sorted to the same group?
// => We could just sort it, because there's always enough space inside the group.
if (droppable.parent().is(draggablesDropable.parent())) {
return true;
}
// Nope, the draggable is being dragged/sorted to another group.
// => Is there an empty droppable left in the group to which the draggable is being dragged/sorted?
else if (droppable.parent().find(".draggable").size() < droppable.parent().find(".droppable").size()) {
return true;
}
// Nothing true?
return false;
},
drop: function(event, ui) {
// The droppable (li element).
var droppable = $(this);
// The draggable (span element).
var draggable = ui.draggable;
// The droppable which contains the draggable, i.e., the parent element of the draggable (li element).
var draggablesDropable = draggable.parent();
// Is the draggable being dragged to it's own droppable?
// => Abort, there's nothing to drag/sort!
if (droppable.is(draggablesDropable)) {
return;
}
// Is the draggable being dragged to an empty droppable?
else if (!droppable.find(".draggable").size()) {
// Just drop the draggable there.
droppable.append(draggable);
}
// Is the draggable being dragged/sorted to the same group?
// => We can just sort it, because there's always enough space inside the group.
else if (droppable.parent().is(draggablesDropable.parent())) {
// Is the draggable being dragged up?
if (droppable.parent().find(".droppable").index(draggablesDropable) > droppable.parent().find(".droppable").index(droppable)) {
// Add the dragged draggable's droppable before the droppable.
draggablesDropable.insertBefore(droppable);
}
// No, the draggable is being dragged down.
else {
// Add the dragged draggable's droppable after the droppable.
draggablesDropable.insertAfter(droppable);
}
}
// Nope, the draggable is being dragged/sorted to another group.
// => Is there an empty droppable left in the group to which the draggable is being dragged/sorted?
else if (droppable.parent().find(".draggable").size() < droppable.parent().find(".droppable").size()) {
// Find the first empty droppable in which the draggable is being dragged/sorted.
var emptyDroppable = $($.grep(droppable.parent().find(".droppable"), function (item) {
// Are there draggables inside this droppable?
// => Return TRUE if not.
return !$(item).find(".draggable").size();
})).first();
// Clone the dragged draggable's droppable before itself, because we need to remember it's position after moving it.
var draggablesDropableClone = draggablesDropable.clone().insertBefore(draggablesDropable);
// Is the draggable being dragged above the empty droppable?
if (droppable.parent().find(".droppable").index(emptyDroppable) > droppable.parent().find(".droppable").index(droppable)) {
// Add the dragged draggable's droppable before the droppable.
draggablesDropable.insertBefore(droppable);
}
// No, the draggable is being dragged below the empty droppable.
else {
// Add the dragged draggable's droppable after the droppable.
draggablesDropable.insertAfter(droppable);
}
// Remove the position of the dragged draggable, because there's still some css left of the dragging.
draggable.css({"top": 0, "left": 0});
// Add the first empty droppable before the cloned draggable's droppable. Remove the latter afterwards.
draggablesDropableClone.before(emptyDroppable).remove();
}
}
});