好吧，让它起作用。我想我可以解决所有问题了：

最终的jQuery有界限

$(document).ready(function(){
    var $bg = $('.bg-img'),
        elbounds = {
            w: parseInt($bg.width()),
            h: parseInt($bg.height())
        },
        bounds = {w: 2350 - elbounds.w, h: 1750 - elbounds.h},
        origin = {x: 0, y: 0},
        start = {x: 0, y: 0},
        movecontinue = false;

    function move (e){
        var inbounds = {x: false, y: false},
            offset = {
                x: start.x - (origin.x - e.clientX),
                y: start.y - (origin.y - e.clientY)
            };

        inbounds.x = offset.x < 0 && (offset.x * -1) < bounds.w;
        inbounds.y = offset.y < 0 && (offset.y * -1) < bounds.h;

        if (movecontinue && inbounds.x && inbounds.y) {
            start.x = offset.x;
            start.y = offset.y;

            $(this).css('background-position', start.x + 'px ' + start.y + 'px');
        }

        origin.x = e.clientX;
        origin.y = e.clientY;

        e.stopPropagation();
        return false;
    }

    function handle (e){
        movecontinue = false;
        $bg.unbind('mousemove', move);

        if (e.type == 'mousedown') {
            origin.x = e.clientX;
            origin.y = e.clientY;
            movecontinue = true;
            $bg.bind('mousemove', move);
        } else {
            $(document.body).focus();
        }

        e.stopPropagation();
        return false;
    }

    function reset (){
        start = {x: 0, y: 0};
        $(this).css('backgroundPosition', '0 0');
    }

    $bg.bind('mousedown mouseup mouseleave', handle);
    $bg.bind('dblclick', reset);
});

原始答案

HTML

<div class="bg-img"></div>

CSS

div.bg-img {
    background-image: url(http://upload.wikimedia.org/wikipedia/commons/9/91/Flexopecten_ponticus_2008_G1.jpg);
    background-position: 0 0;
    background-repeat: no-repeat;
    background-color: blue;
    border: 1px solid #aaa;
    width: 250px;
    height: 250px;
    margin: 25px auto;
}

jQuery

$(document).ready(function(){
    var $bg = $('.bg-img'),
        origin = {x: 0, y: 0},
        start = {x: 0, y: 0},
        movecontinue = false;

    function move (e){
        var moveby = {
            x: origin.x - e.clientX,
            y: origin.y - e.clientY
        };

        if (movecontinue === true) {
            start.x = start.x - moveby.x;
            start.y = start.y - moveby.y;

            $(this).css('background-position', start.x + 'px ' + start.y + 'px');
        }

        origin.x = e.clientX;
        origin.y = e.clientY;

        e.stopPropagation();
        return false;
    }

    function handle (e){
        movecontinue = false;
        $bg.unbind('mousemove', move);

        if (e.type == 'mousedown') {
            origin.x = e.clientX;
            origin.y = e.clientY;
            movecontinue = true;
            $bg.bind('mousemove', move);
        } else {
            $(document.body).focus();
        }

        e.stopPropagation();
        return false;
    }

    function reset (){
        start = {x: 0, y: 0};
        $(this).css('backgroundPosition', '0 0');
    }

    $bg.bind('mousedown mouseup mouseleave', handle);
    $bg.bind('dblclick', reset);
});