Flex Examples » getElementIndex() http://blog.flexexamples.com Just a bunch of Adobe Flex Examples Wed, 26 Jan 2011 18:09:51 +0000 en hourly 1 Auto scrolling the contents of a VGroup container in Flex 4 http://blog.flexexamples.com/2009/11/02/auto-scrolling-the-contents-of-a-vgroup-container-in-flex-4/ http://blog.flexexamples.com/2009/11/02/auto-scrolling-the-contents-of-a-vgroup-container-in-flex-4/#comments Mon, 02 Nov 2009 23:50:34 +0000 Peter deHaan http://blog.flexexamples.com/?p=2136 The following example shows how you can tab through a series of Spark TextInput controls in Flex 4 and auto-scroll the VGroup container so that the currently focused text field has focus by using the fractionOfElementInView() method, getScrollPositionDeltaToElement() method, and verticalScrollPosition property.

Full code after the jump.

And a big thanks to The following example shows how you can tab through a series of Spark TextInput controls in Flex 4 and auto-scroll the VGroup container so that the currently focused text field has focus by using the fractionOfElementInView() method, getScrollPositionDeltaToElement() method, and verticalScrollPosition property.

Full code after the jump.

And a big thanks to Hans Muller for explaining this all to me.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/11/02/auto-scrolling-the-contents-of-a-vgroup-container-in-flex-4/ -->
<s:Application name="Spark_VerticalLayout_getScrollPositionDeltaToElement_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark">
 
    <fx:Script>
        <![CDATA[
            import mx.core.IVisualElement;
            import spark.layouts.VerticalLayout;
 
            protected function textinput_focusInHandler(evt:FocusEvent):void {
                var idx:int = vg.getElementIndex(evt.currentTarget as IVisualElement);
                var lay:VerticalLayout = vg.layout as VerticalLayout;
                if (lay.fractionOfElementInView(idx) < 1) {
                    lay.verticalScrollPosition += lay.getScrollPositionDeltaToElement(idx).y;
                }
            }
        ]]>
    </fx:Script>
 
    <s:Scroller id="scrllr"
            focusEnabled="false"
            hasFocusableChildren="true"
            height="100"
            horizontalCenter="0" verticalCenter="0">
        <s:VGroup id="vg"
                paddingLeft="10" paddingRight="10" paddingTop="10" paddingBottom="10">
            <s:TextInput text="One" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Two" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Three" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Four" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Five" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Six" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Seven" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Eight" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Nine" focusIn="textinput_focusInHandler(event);" />
        </s:VGroup>
    </s:Scroller>
 
</s:Application>

If you wanted to add a little scrolling animation (’cause who DOESN’T love animation!?), you could use an Animate with a SimpleMotionPath, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/11/02/auto-scrolling-the-contents-of-a-vgroup-container-in-flex-4/ -->
<s:Application name="Spark_VerticalLayout_getScrollPositionDeltaToElement_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark">
 
    <fx:Script>
        <![CDATA[
            import mx.core.IVisualElement;
            import spark.layouts.VerticalLayout;
 
            protected function textinput_focusInHandler(evt:FocusEvent):void {
                var idx:int = vg.getElementIndex(evt.currentTarget as IVisualElement);
                var lay:VerticalLayout = vg.layout as VerticalLayout;
                if (lay.fractionOfElementInView(idx) < 1) {
                    pth.valueBy = lay.getScrollPositionDeltaToElement(idx).y;
                    anim.play([lay]);
                }
            }
        ]]>
    </fx:Script>
 
    <fx:Declarations>
        <s:Animate id="anim" duration="500">
            <s:motionPaths>
                <s:SimpleMotionPath id="pth" property="verticalScrollPosition" />
            </s:motionPaths>
        </s:Animate>
    </fx:Declarations>
 
    <s:Scroller id="scrllr"
            focusEnabled="false"
            hasFocusableChildren="true"
            height="100"
            horizontalCenter="0" verticalCenter="0">
        <s:VGroup id="vg"
                paddingLeft="10" paddingRight="10" paddingTop="10" paddingBottom="10">
            <s:TextInput text="One" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Two" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Three" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Four" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Five" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Six" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Seven" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Eight" focusIn="textinput_focusInHandler(event);" />
            <s:TextInput text="Nine" focusIn="textinput_focusInHandler(event);" />
        </s:VGroup>
    </s:Scroller>
 
</s:Application>

This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.

 
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