Flex 4 滚轮 [英] Flex 4 Scroller

问题描述

在我的应用程序中，我使用了 滚动器 组件.我似乎无法弄清楚应该在哪个事件上设置侦听器才能知道何时滚动内容.我在 Scroller.verticalScrollBar 属性上尝试了 Event.CHANGE 但显然当用户使用鼠标滚轮或箭头键滚动时该事件不会触发.

Within my application I'm using a Scroller component. I can't seem to figure out which event I should set up a listener on in order to know when content is scrolled. I tried Event.CHANGE on Scroller.verticalScrollBar property but apparently that event doesn't fire when the user scrolls with a mouse wheel or arrow keys.

推荐答案

您可以在 Scroller 的视口上监听 propertyChange 事件.下面是一个演示如何完成此操作的应用程序:

You can listen for the propertyChange event on the viewport of the Scroller. Here is an application that demonstrates how this might be done:

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               creationComplete="init()">
    <fx:Script>
        <![CDATA[
            import mx.events.PropertyChangeEvent;

            private function init():void {
                // spark Scroller: listen on the viewport property
                myScroller.viewport.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, handle);
            }

            /**
             * Handle scroll position changes
             */
            private function handle(e:PropertyChangeEvent):void {
                if (e.source == e.target && e.property == "verticalScrollPosition")
                    trace(e.property, "changed to", e.newValue);
                if (e.source == e.target && e.property == "horizontalScrollPosition")
                    trace(e.property, "changed to", e.newValue);
            }
        ]]>
    </fx:Script>

    <s:Scroller id="myScroller" width="100" height="100">
        <s:Group>
            <s:Button label="large content" width="300" height="300"/>
        </s:Group>
    </s:Scroller>

</s:Application>

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