How to determine mouse position outside stage, and center the cursor?

Question

I was wondering if it is possible to have my flash game determine the position of the mouse, even when the cursor is not inside the stage.

My movie clip should move horizontally between x = 100 and 500, using mouseX for movement:

private var previousX : int;
private var mc : MovieClip;
//...
private function update(e:Event = null):void
{
    var deltaX : int = (mouseX - previousX) / 2;
    mc.x = Math.min(Math.max(mc.x + deltaX, 100), 500);
    previousX = mouseX;
}

The above code works fine, as long as the cursor is above my flash game. When the cursor is outside the stage, mouseX stops updating. I realise that mouseX is probably not what I'm looking for, so I was wondering if there was any other way of finding the cursors position.

I hoped there was a way to set the mouse position directly, so I could center it after every update, so it would almost never be able to leave the frame in the first place. Is that possible?

Answer 1

There is only one way to determine it, for which you will need to make the behavior from mouse-move to click-and-drag. When mouse is clicked over the stage, and then moved outside, it's position (x,y) can be determined. Otherwise, i think it's not possible. I had a similar situation, where ultimately, we were forced to make the game full-screen.

Here is how to test it :

import flash.events.Event;

//CLICK AND DRAG ( DON'T DO A MOUSE UP )
stage.addEventListener(MouseEvent.MOUSE_MOVE,mv)

function mv(e:Event )
{
    trace(mouseX,mouseY);
}

Answer 2

You can't confine the system cursor to a region with Flash. What you can do is hide the system mouse-cursor using Mouse.hide() (only works when the cursor is over your game-area), then use a custom cursor instead. There's also an event called Event.MOUSE_LEAVE which will fire whenever the mouse leaves the stage area. You can't tell where the mouse will be on screen, but at least you know that it's no longer inside your game-area. Eg.

stage.addEventListener(Event.MOUSE_LEAVE, handleMouseLeave);

Here's a tutorial that explains the above in more detail.