grouping draggable objects with jquery-ui draggable

Question

Hello,

I want to use jquery draggable/droppable to let the user select a group of objects (each one has a checkbox in the corner) and then drag all the selected objects as a group...

I can't figure out for the life of me how to do it haha.

Here is what I'm thinking will lead to a usable solution, on each draggable object, use the start() event and somehow grab all the other selected objects and add them to the selection

I was also considering just making the dragged object look like a group of objects (they're images, so a pile of photos maybe) for performance reasons. I think using the draggable functionality might fall over if you drag several dozen objects at once, does that sound like a better idea?

Answer 1

Performance Idea:

Make an invisible 'group object'. When the items are checked, make them children of the group object, when unselected, set them back as children of the document body, or static parent or whatever. You'll have to translate the objects' position to make sure they don't jump around, also attach/detach your mouse event handlers to the children of the group as you add/remove them.

When you get a mouse down/up event on any of the children, what you'll move is actually that group object.

This should make it simpler overall.

Answer 2

This the exact thing I'm trying to do. So far I've not been successful, but I've found this guy done it in a very complicated way. you could check it out maybe you could do somthing with that.

This should be a feature in draggable. I hope they implement it sooner than later

Answer 3

You could use the draggable's helper option to drag groups of items.

For example, if your draggables have checkboxes, you can return the selected items from the helper function like so:

$('#dragSource li').draggable({
  helper: function(){
    var selected = $('#dragSource input:checked').parents('li');
    if (selected.length === 0) {
      selected = $(this);
    }
    var container = $('<div/>').attr('id', 'draggingContainer');
    container.append(selected.clone());
    return container; 
  }
});

Demo

I've setup a demo with draggable images with checkboxes and somewhat fluid layout:

http://jsbin.com/awagi

Note: I've only tested it in Firefox; I suspect IE won't like some of the CSS.

Answer 4

What I've done for this is created a function that you give the slave / master elements to, which creates a bind() function for the master (I'm only allowing a drag from the master in this case, you can work around this I'm sure), which makes the slave follow it around using standard jQuery css.

    function overlap(slave,master) {
        $('a#groupTheseBlocks').click(function(){
            master.bind('drag', groupBlocks);
            slave.draggable('disable');

            // remember where the slave is in relation to the master
            sLeftRef = (slave.offset().left - master.offset().left);
            sTopRef = (slave.offset().top - master.offset().top);
        });


        function groupBlocks() {
            var left = master.offset().left;
            var top = master.offset().top;

            slave.draggable('disable');
            slave.css('left', (left + sLeftRef) + 'px');
            slave.css('top', (top + sTopRef) + 'px');

        } 
    }

I guess I'll post more to this once I have a working example. As it stands this is working for me. What is missing is a way to call overlap(slave, master) with the elements you want to group together. I'm doing this in a really specific way. You can clever a way to do it, I'm sure.