Dragging an NSImageView

I have an NSImageView that I need to drag it around. I know to use the mouseDragged: method in the NSImageView subclass. I looked in the Apple Documentation and I didn't see a property or method for getting the NSImageView's position. How can I use the mouseDragged: method so the user can drag the NSImageView only horizontally and vertically. The movement will also need to be animated.
Thanks!

 

I figured out how to move it around, but I don't know how to only allow horizontal and vertical movement (No moving it in circles and diagonal movement).
Please Help
Thanks

 

I just want to limit the movement to up/down and side-to-side.
I am using this to allow the dragging movement:

Code:

- (void)mouseDown:(NSEvent *)theEvent
{
	    lastDragLocation = [theEvent locationInWindow]; 
}

-(void)mouseDragged:(NSEvent *)theEvent{


    NSPoint newDragLocation = [theEvent locationInWindow];
    NSPoint origin = [self frame].origin;
    origin.x += (-lastDragLocation.x + newDragLocation.x);
    origin.y += (-lastDragLocation.y + newDragLocation.y);
    [self setFrameOrigin:origin];
    lastDragLocation = newDragLocation;

}

How could I modify this to only allow left/right and up/down movement?