Flex Spark List Mouse Wheel Scroll Speed

Question

I have a component extending a Spark List, and when I scroll using the mouse wheel it scrolls too much in one go. I have tried looking for the handler that deals with mouse wheel scrolling in the List class and VerticalLayout class to override but I cannot find it.

Is there another way I'm supposed to change this, or am I missing something?

Answer 1

The "horizontalLineScrollSize" and "verticalLineScrollSize" properties determine how many pixels to scroll when the user selects the scroll bar arrows. The "verticalLineScrollSize" property also controls the amount of scrolling when using the "mouse wheel". The default value is 5 pixels. The "horizontalPageScrollSize" and "verticalPageScrollSize" properties determine how many pixels to scroll when the user selects the "scroll bar track". The default value is 20 pixels.

More details: http://livedocs.adobe.com/flex/3/html/help.html?content=containers_intro_4.html

Answer 2

The "delta" property of MouseEvent.MOUSE_WHEEL defines how many lines will be scrolled by one wheel-scrolling. You could try changing it in the MOUSE_WHEEL handler (during capture phase). For example the following code will scroll line-by-line:

        protected function init(event:FlexEvent):void
        {
            list.addEventListener(MouseEvent.MOUSE_WHEEL, list_mouseWheelHandler, true);
        }

        protected function list_mouseWheelHandler(event:MouseEvent):void
        {
            event.delta = event.delta > 0 ? 1 : -1;
        }