Setting text selection on a TextArea control in Flex

The following example shows how you can set the selected text in a Flex TextArea control by using the setSelection() method.

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/04/25/setting-text-selection-on-a-textarea-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.core.IUITextField;
            import mx.events.SliderEvent;
            import mx.controls.sliderClasses.Slider;

            private function slider_change(evt:SliderEvent):void {
                var value1:int = Slider(evt.currentTarget).values[0];
                var value2:int = Slider(evt.currentTarget).values[1];
                var min:int = Math.min(value1, value2);
                var max:int = Math.max(value1, value2);
                textArea.setSelection(min, max);
            }

            private function init():void {
                var tf:IUITextField = textArea.mx_internal::getTextField();
                tf.alwaysShowSelection = true;
                textArea.verticalScrollPosition = 0;
            }
        ]]>
    </mx:Script>

    <mx:String id="lorem" source="lorem.html" />

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="setSelection():">
                <mx:HSlider id="slider"
                        minimum="0"
                        maximum="{textArea.htmlText.length}"
                        thumbCount="2"
                        liveDragging="true"
                        allowThumbOverlap="true"
                        snapInterval="1"
                        dataTipPrecision="0"
                        change="slider_change(event);" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:TextArea id="textArea"
            htmlText="{lorem}"
            textAlign="justify"
            condenseWhite="true"
            width="100%"
            height="100%"
            creationComplete="init();" />

</mx:Application>

View source is enabled in the following example.

You can also set the selected text in a TextArea control by setting the selectionBeginIndex and selectionEndIndex properties, as seen in the following example:

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/04/25/setting-text-selection-on-a-textarea-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.core.IUITextField;
            import mx.events.SliderEvent;
            import mx.controls.sliderClasses.Slider;

            private function slider_change(evt:SliderEvent):void {
                textArea.selectionBeginIndex = beginSlider.value;
                textArea.selectionEndIndex = endSlider.value;

                textArea.validateNow();
                beginLabel.text = textArea.selectionBeginIndex.toString();
                endLabel.text = textArea.selectionEndIndex.toString();
            }

            private function init():void {
                var tf:IUITextField = textArea.mx_internal::getTextField();
                tf.alwaysShowSelection = true;
                textArea.verticalScrollPosition = 0;
            }
        ]]>
    </mx:Script>

    <mx:String id="lorem" source="lorem.html" />

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="selectionBeginIndex:"
                    direction="horizontal">
                <mx:HSlider id="beginSlider"
                        minimum="0"
                        maximum="{textArea.htmlText.length}"
                        value="0"
                        liveDragging="true"
                        change="slider_change(event);" />
                <mx:Label id="beginLabel" />
            </mx:FormItem>
            <mx:FormItem label="selectionEndIndex:"
                    direction="horizontal">
                <mx:HSlider id="endSlider"
                        minimum="0"
                        maximum="{textArea.htmlText.length}"
                        value="0"
                        snapInterval="1"
                        liveDragging="true"
                        change="slider_change(event);" />
                <mx:Label id="endLabel" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:TextArea id="textArea"
            htmlText="{lorem}"
            textAlign="justify"
            condenseWhite="true"
            width="100%"
            height="100%"
            creationComplete="init();" />

</mx:Application>

View source is enabled in the following example.

5 thoughts on “Setting text selection on a TextArea control in Flex

  1. Thanks for sharing this sample, that was helpful

    2 notes regarding this sample:

    1) Sample code will work only for Adobe Flex SDK 3 and higher, because it uses interface mx.core.IUITextField that had appeared only from Adobe Flex SDK 3

    2) Why we have to set explicitly tf.alwaysShowSelection = true in order to make method public method of textArea “setSelection” working, why tf.alwaysShowSelection property is not set to TRUE inside mx:TextArea code?

  2. Is there any way to set styles on the selection? E.G., can you set the backgroundColor, backgroundAlpha, etc.?

  3. Pete Moss,

    I don’t believe you can in Flex 3.x, but Flex Gumbo/Flash Player 10 will offer greater control over text selection colors.

    Peter

  4. Consistently the clearest and most useful Flex blog in town. Every time I google a Flex problem I have my fingers crossed that this blog will come up in the search results. Thanks for all your efforts. :-)

    rob

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