Mousedown on body and drag the page up or down, like on a pdf

Question

How would I make it so I can mousedown on the body on my page, then drag the page up or down, like you can in a PDF?

Basically I want to be able to drag the whole page u

Answer 1

Quick fix for the scrollbar problem: use $(document.body) instead of $(document).

Still, the animation behave strangely sometimes, especially with repetitive scrolls. (eg. scrolling up and the following animation scrolls down).

Since the OP asked for a PDF viewer-like scrolling (and not an iPhone-like scrolling) that don't involve any kind of animation, I guess we could put Sohnee's code on a diet and write this:

    var gesturesY = 0;
    var startPosition = 0;
    var isMouseDown = false;

    $(document.body).mousemove( function (e) {
        gesturesY = parseInt(e.pageY, 10);
        if (isMouseDown) {
            window.scrollBy(0, startPosition - gesturesY);
            return false;
        }
    });

    $(document.body).mousedown( function() {
        startPosition = gesturesY;
        isMouseDown = true;
    });

    $(document.body).mouseup( function() {
        isMouseDown = false;
        return false;
    });