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问题:

I have two elements:

1. A parent of fixed height, overflow:hidden

2. Its child, of larger fixed height.

<style type="text/css">
    .myList {list-style:none; margin:0px; padding:1px;}
    .myList li{ height:50px;  margin:4px; padding:2px;}
    .dragPanel {height:230px; border:solid; overflow:hidden;}
</style>

<div class="dragPanel">
    <ul class="myList">
        <li>1</li>
        <li>2</li>
        ...   ....
        <li>8</li>
        <li>9</li>
    </ul>
</div>

I want to be able to drag the list up and down within the parent div. I am using the jquery ui draggable plugin to achieve verticle dragging, but I am unsure how to constrain the list within the parent div.

<script type="text/javascript" src="http://jqueryui.com/latest/jquery-1.3.2.js"></script>
<script type="text/javascript" src="http://jqueryui.com/latest/ui/ui.core.js"></script>
<script type="text/javascript" src="http://jqueryui.com/latest/ui/ui.draggable.js"></script>

<script type="text/javascript">
    $(document).ready(function() {
        $('.dragPanel').addClass("hover");
        $('.myList').draggable({ axis: 'y' });
    });
</script>

How would I go about setting verticle upper and lower limits for the posistion of the list?

回答1:

Use the containment option:

$('.myList').draggable({
    axis: 'y',
    containment: 'parent'
});

回答2:

I had the same problems and the answers didn't help me. Some javascript later I think the following is a better solution.

(Anybody knows how to turn this into a jQuery plugin?)

<!DOCTYPE html>
<html>
<head>
    <title>Draggable limited to the container</title>
    <style type="text/css">
    #container {
        cursor: move;
        overflow: hidden;
        width: 300px;
        height: 300px;
        border: 1px solid black;
    }
    </style>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/jquery-ui.min.js"></script>
    <script type="text/javascript">
    $(function() {
        $.globalVars = {
            originalTop: 0,
            originalLeft: 0,
            maxHeight: $("#draggable").height() - $("#container").height(),
            maxWidth: $("#draggable").width() - $("#container").width()
        };
        $("#draggable").draggable({
            start: function(event, ui) {
                if (ui.position != undefined) {
                    $.globalVars.originalTop = ui.position.top;
                    $.globalVars.originalLeft = ui.position.left;
                }
            },
            drag: function(event, ui) {
                var newTop = ui.position.top;
                var newLeft = ui.position.left;
                if (ui.position.top < 0 && ui.position.top * -1 > $.globalVars.maxHeight) {
                    newTop = $.globalVars.maxHeight * -1;
                }
                if (ui.position.top > 0) {
                    newTop = 0;
                }
                if (ui.position.left < 0 && ui.position.left * -1 > $.globalVars.maxWidth) {
                    newLeft = $.globalVars.maxWidth * -1;
                }
                if (ui.position.left > 0) {
                    newLeft = 0;
                }
                ui.position.top = newTop;
                ui.position.left = newLeft;
            }
        });
    });
    </script>
</head>
<body>
    <div id="container">
        <img id="draggable" src="avatar.jpg" />
    </div>
</body>
</html>

回答3:

Ok,

Here is the route I have gone down...

When the page is loaded, I add a container div around the draggable list. I set it's height to twice that of the list, then position it up the page a little:

<script type="text/javascript">
  $(document).ready(function() {
      CreateContainerDiv();
      $('.dragPanel').addClass("hover");
      $('.myList').draggable({ axis: 'y', containment: 'parent' });
  });

    function CreateContainerDiv() {
        var dragPanel = $('.dragPanel');
        var dragTarget = $('.myList');

        // add the container panel
        var newPanelHeight = dragTarget.outerHeight() * 2 - dragPanel.outerHeight();
        dragTarget.wrap(document.createElement("div"));

        // set its height and put it in the right place
        dragTarget.parent().css("height", newPanelHeight);
        dragTarget.parent().css("position", "relative");
        var newPanelPosition = ((dragTarget.outerHeight() * -1) / 2);
        dragTarget.parent().css("top", newPanelPosition);         
    }
</script>

The list is then contained to this new element.

This appears to do the job, but the positioning is all a little shakey if the list has any padding / margin applied. Any thoughts on that would be appreicated!

------Edit ---------

Ok, I think I have solved the placement issue. I have turned this into a plugin so other people don't have to spend time creating this functionality.

jQuery Drag-gable List at Github

回答4:

You don't have to drag anything for that kind of structure. What you need is to set up the parent div with overflow-x:hidden; and overflow-y:scroll;. That way, its content will be scrollable.

If you want to hide the scrollbar, just put this property: .dragPanel::-webkit-scrollbar{width:0 !important} and that's it! I don't really know why you were thinking of dragging elements instead of just scrolling the content (which is the correct way to carry out this kind of "problems"). Anyways, I hope it helps anybody who needs to fit the same necesity. Greetings!