Tag Scrollbar

Flex 3: disable scrollbar in a List

De List control in Flex 3 beschikt over de mogelijkheid de scrollbar te beïnvloeden. Dit is echter beperkt tot horizontalScrollPolicy & verticalScrollPolicy. Met deze twee property’s kan je bepalen of je de scrollBar al dan niet toont.

Maar ik wou – bij het aanpassen van een item uit de list – niet dat de scrollBar zou verdwijnen, maar disabled zou worden. Dit resultaat heb ik bereikt door gebruik te maken van volgende methode:

var lSubtitles:CustomList = new CustomList();
lSubtitles.enableScrollBar(false);
// Invalidate the CustomList so the applications knows
// he needs to refresh the list
lSubtitles.invalidateList();

De klasse:

package classes.views.subtitles.list
{
import flash.events.Event;
import flash.events.MouseEvent;

import mx.controls.List;
import mx.controls.scrollClasses.ScrollBar;

// This custom list is programmed to be able to disable
// the scrollbar which is by default impossible.
// This is a useful addition to the current
// functionality of ScrollPolicy OFF|ON|AUTO
// (which hides/shows the scrollbar)
public class CustomList extends List
{
 private var _bEnabledScrollBar:Boolean = true;

// Constructor
public function CustomList()
{
 super();
}

// Function to set whether the scrollbar should
// be put enabled or disabled
public function enableScrollBar(bValue:Boolean):void
{
  _bEnabledScrollBar = bValue;
  if(!bValue)
  {
   // This is the event which is triggered when a
   // user scrolls with his mouse wheel.
   // Check if this object has such an event listener
   if(super.hasEventListener(MouseEvent.MOUSE_WHEEL))
   {
    // This is the protected event handler which
    // resides inside the ListBase
    super.removeEventListener(MouseEvent.MOUSE_WHEEL,
    mouseWheelHandler);
   }
  }
  else
  {
   // This is the event which is triggered when a user
   // scrolls with his mouse wheel. Make sure this
   // doesn't has such an event listener
   if(!super.hasEventListener(MouseEvent.MOUSE_WHEEL))
   {
    // This is the protected event handler which
    // resides inside the ListBase
    super.addEventListener(MouseEvent.MOUSE_WHEEL,
    mouseWheelHandler);
   }
  }
}

// The configure scrollbar method manages
// the functionality of the scrollbars this method
// get's called when the invalidateDisplayList is called
protected override function configureScrollBars():void
{
 // If the _bDisabledScrollBar boolean is set to true;
 // the scrollbar should be disabled!
 if(!_bEnabledScrollBar)
 {
  // Loop trough the children of the list and
  // find the scrollbar
  for(var t:int = 0; t < this.numChildren; t++)
  {
   if(this.getChildAt(t) is ScrollBar)
   {
    var sb:ScrollBar = this.getChildAt(t) as ScrollBar;
    sb.enabled = false;
    sb.mouseEnabled = false;
    this.mouseEnabled = false;
   }
  }
 }
 // Else just use the default behavior of the list
 else
 {
     super.configureScrollBars();
 }
}
}
}

Een screenshot van het resultaat:

example