jquery ui sortables connect lists: copy items - jquery-ui

Question

I have two lists, I want both of them to be sortable and want to be able to copy (drag) items from list1 to list2 and vice versa.
http://jqueryui.com/demos/sortable/#connect-lists
Is what I want, but the items are moved, not copied.
I did a few experiments with draggables and droppables, but I can't get to to work keeping them sortable. For example: http://jsfiddle.net/tunafish/dvXmf/

Answer 1

OK here is my app; two lists of images, sortable and you can copy over from the connected list.
If an item already exists in the target it's disabled.
Hopefully useful to someone...
JSFiffle here: http://jsfiddle.net/tunafish/VBG5V/
CSS:
.page { width: 410px; padding: 20px; margin: 0 auto; background: darkgray; }
.album { list-style: none; overflow: hidden;
width: 410px; margin: 0; padding: 0; padding-top: 5px;
background: gray;
}
.listing { margin-bottom: 10px; }
.album li { float: left; outline: none;
width: 120px; height: 80px; margin: 0 0 5px 5px; padding: 5px;
background: #222222;
}
li.placeholder { background: lightgray; }
JS:
$("ul, li").disableSelection();
$(".album, .favorites").sortable({
connectWith: ".album, .favorites",
placeholder: "placeholder",
forcePlaceholderSize: true,
revert: 300,
helper: "clone",
stop: uiStop,
receive: uiReceive,
over: uiOver
});
$(".album li").mousedown(mStart);
var iSender, iTarget, iIndex, iId, iSrc, iCopy;
var overCount = 0;
/* everything starts here */
function mStart() {
// remove any remaining .copy classes
$(iSender + " li").removeClass("copy");
// set vars
if ($(this).parent().hasClass("listing")) { iSender = ".listing"; iTarget = ".favorites"; }
else { iSender = ".favorites"; iTarget = ".listing"; }
iIndex = $(this).index();
iId = $(this).attr("id");
iSrc = $(this).find("img").attr("src");
iCopy = $(iTarget + " li img[src*='" + iSrc + "']").length > 0; // boolean, true if there is allready a copy in the target list
// disable target if item is allready in there
if (iCopy) { $(iTarget).css("opacity","0.5").sortable("disable"); }
}
/* when sorting has stopped */
function uiStop(event, ui) {
// enable target
$(iTarget).css("opacity","1.0").sortable("enable");
// reset item vars
iSender = iTarget = iIndex = iId = iSrc = iCopy = undefined;
overCount = 0;
// reinit mousedown, live() did not work to disable
$(".album li").mousedown(mStart);
}
/* rolling over the receiver - over, out, over etc. */
function uiOver(event, ui) {
// only if item in not allready in the target
if (!iCopy) {
// counter for over/out (numbers even/uneven)
overCount++;
// if even [over], clone to original index in sender, show and fadein (sortables hides it)
if (overCount%2) {
if (iIndex == 0) { ui.item.clone().addClass("copy").attr("id", iId).prependTo(iSender).fadeIn("slow"); }
else { ui.item.clone().addClass("copy").attr("id", iId).insertAfter(iSender + " li:eq(" + iIndex + ")").fadeIn("slow"); }
}
// else uneven [out], remove copies
else { $(iSender + " li.copy").remove(); }
}
// else whoooooo
}
/* list transfers, fix ID's here */
function uiReceive(event, ui) {
(iTarget == ".favorites") ? liPrefix = "fli-" : liPrefix = "lli-";
// set ID with index for each matched element
$(iTarget + " li").each(function(index) {
$(this).attr("id", liPrefix + (index + 1)); // id's start from 1
});
}
HTML:
<div class="page">
<div class="container">
<h2>Photo Album</h2>
<ul class="listing album">
<li id="li-1"><img src="tn/001.jpg" /></li>
<li id="li-2"><img src="tn/002.jpg" /></li>
<li id="li-3"><img src="tn/003.jpg" /></li>
<li id="li-4"><img src="tn/004.jpg" /></li>
<li id="li-5"><img src="tn/005.jpg" /></li>
</ul>
</div>
<div style="clear:both;"></div>
<div class="container">
<h2>Favorites</h2>
<ul class="favorites album">
<li id="fli-1"><img src="tn/001.jpg" /></li>
<li id="fli-2"><img src="tn/002.jpg" /></li>
<li id="fli-3"><img src="tn/010.jpg" /></li>
</ul>
</div>
</div>

Answer 2

I have to say that FFish's answer to this has been incredibly helpful to me.
I'd make one suggestion; if the lists are being constantly changed the mousedown event seem to be called numerous times because of the re-registering of the event on all the child objects. It might be a bit of a kludge, but I've added an unbind first to ensure the mousedown event is only called once.
$(".album li").mousedown(mStart);
to
$(".album li").unbind('mousedown', mStart).mousedown(mStart);