bump

Do you mean the example above ?

Ok,

I just took my Notebook in the garden with me and created a Slider Example.

On my MacBookPro it is working ! but not on my PC.

Here you can try the code:

http://wensauer.info/flex/ConstantDeltaSlider/ConstantDeltaSlider.html

For some reason it is neither working at all for a HScrollBar.

Have a Nice Day

Marc

I had a slightly different problem with mouse wheel scrolling; the scroller would jump WAY too far with each click of the wheel.  I figured out a solution that I think is much simpler than trying to subclass the scrollbar or intercept mouse wheel events.  The viewport for a scroller dictates how far to scroll through the getVerticalScrollPositionDelta method in IViewport, so I extended s:Group and overrode that method to return a smaller value.  Now I just use the new group subclass as the viewport for a Scroller and set the step size to something reasonable and it works great!  This allows you to mimic the old Canvas.verticalLineScrollSize property which was very useful for solving this problem.  Here's the code, I hope this helps someone overcome the stupid scrolling in Flex4.

ControlledScrollGroup.as

package scroll
{    
    import spark.components.Group;
 
    public class ControlledScrollGroup extends Group
    {
        private var _step_size:int = 0;
        
        public function get stepSize():int
        {
            return _step_size;
        }
        
        public function set stepSize(value:int):void
        {
            _step_size = value;
        }
        
        override public function getVerticalScrollPositionDelta(navigationUnit:uint):Number
        {
            var megaValue:Number = super.getVerticalScrollPositionDelta(navigationUnit);
            
            if(megaValue == 0)
            {
                return 0;
            }
            
            var smallerValue:int =  _step_size;
            
            if(smallerValue ==0)
            {
                return megaValue;
            }
            
            if(megaValue < 0)
            {
                smallerValue = -1*smallerValue;
            }
            
            return smallerValue;
        }
        
        public function ControlledScrollGroup()
        {
            super();
        }
    }
}

usage:

<s:Scroller  height="400" width="400">
     <scroll:ControlledScrollGroup stepSize="40">
          <... content what needs scrolln' ...>
     </scroll:ControlledScrollGroup> 
</s:Scroller>

Thanks for this solution K-Spar. It works like a charm and very easy to implement

K-spar, I can't thank you enough for your solution! Works great. Boy was I pulling my hair out to solve this problem...

For others reading this, note that Flex 4 default <s:Scroller> with a child that is <s:VGroup> will jump one vertical page height when using the mouse THUMBWHEEL when you rotate the thumbwheel one click. This may be too much for some applications.

Conversely, if you use a child of <s:Group> or <s:HGroup> then the Flex 4 behaviour is to jump 1 (or maybe it's two, but it's very small) pixel with each tick (or click) of the mouse thumbwheel. This is likely too small for many applications.

K-spar's solution above allows you to adjust the scroll step size to whatever you like, without adding an event listener (event listeners may impact performance).

UPDATE:

After using this solution a while, I observed that mouse left-clicking in the scroller gutter doesn't follow the usual convention of moving the scrollbar a large jump (the scrollbar behaves as if the user had simply clicked the thumbwheel once). So, the following if-else statement restored this feature:

  if (megaValue==1 || megaValue==-1)

  return smallerValue;

  else

  return megaValue;

Then, just comment out the last return. Here's the full code for reference:

package path.for.my.package

{   

          import spark.components.Group;

          public class ControlledScrollGroup extends Group

          {

                    private var _step_size:int = 0;

                    public function get stepSize():int

                    {

                              return _step_size;

                    }

                    public function set stepSize(value:int):void

                    {

                              _step_size = value;

                    }

                    override public function getVerticalScrollPositionDelta(navigationUnit:uint):Number

                    {

                              var megaValue:Number = super.getVerticalScrollPositionDelta(navigationUnit);

                              if(megaValue == 0)

                              {

                                        return 0;

                              }

                              var smallerValue:int =  _step_size;

                              if(smallerValue ==0)

                              {

                                        return megaValue;

                              }

                              if(megaValue < 0)

                              {

                                        smallerValue = -1*smallerValue;

                              }

  if (megaValue==1 || megaValue==-1) // allows mouse left-click in gutter to jump scrollbar into new position

                                        return smallerValue;

  else

                                        return megaValue;

  //return smallerValue; // commented out

                    }

                    public function ControlledScrollGroup()

                    {

  super();

                    }

          }

}

Message was edited by: abc123456@!#

The better way is to catch FlexMouseEvent.MOUSE_WHEEL_CHANGING on VScrollBar or HScrollBar, ( addEventListener(FlexMouseEvent.MOUSE_WHEEL_CHANGING,mouseWheelChangingHandler)) or override VScrollBar.dispatchEvent to change the delta, for more control override LayoutBase.getVerticalScrollPositionDelta(navigationUnit:uint) method

Note! Remember to keep sign of delta.