Scroll to the right and center on the player

Question

I'm making a platform game. My game level is very large and I'd like to make the gameLevel scroll when the player is walking.
So far it's scrolling, but the scrolling speed is not fast enough and when the player is walking to the right, he goes out of the screen.
Do you know how I can speed up the scrolling in order to prevent the character to exceed the middle of the screen ?
Here's my code for the scrolling screen :
public function scrollWithHero() {
   var stagePosition:Number = gamelevel.x+hero.mc.x;
   var rightEdge:Number = 400-edgeDistance;
   var leftEdge:Number = edgeDistance;
   if (stagePosition > rightEdge) {
  gamelevel.x -= (stagePosition-rightEdge);
   if (gamelevel.x < -(gamelevel.width-stage.stageWidth)) gamelevel.x = -(gamelevel.width-stage.stageWidth);
   if (stagePosition < leftEdge) {
  gamelevel.x += (leftEdge-stagePosition);
   if (gamelevel.x > 0) gamelevel.x = 0;
I could put something like this
if (hero.mc.x > 300){
//What should I put here ?
(x=300 is the position of my player when he is in the center of the screen)
Thank you for your help

Answer 1

it looks like you want easing so scrolling slows as stagePosition nears an edge.  if so, you can use:
var speed:Number = something between 0 and 1 (closer to 1 is slower, closer to 0 is faster)
gamelevel.x = speed*gamelevel.x+(1-speed)*an edge;