Creating a multiline Spark CheckBox control in Flex 4

The following example shows how you can create a multiline Spark CheckBox control in Flex 4 by creating a custom skin and setting the maxDisplayedLines property.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see 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/2010/04/03/creating-a-multiline-spark-checkbox-control-in-flex-4/ -->
<s:Application name="Spark_CheckBox_skin_maxDisplayedLines_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <s:CheckBox id="ch"
            label="The quick brown fox jumps over the lazy dog"
            skinClass="skins.CustomCheckBoxSkin"
            width="200"
            horizontalCenter="0" verticalCenter="0" />
 
</s:Application>

And the custom Spark CheckBox skin, skins/CustomCheckBoxSkin.mxml is as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/04/03/creating-a-multiline-spark-checkbox-control-in-flex-4/ -->
<s:SparkSkin name="CustomCheckBoxSkin"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:fb="http://ns.adobe.com/flashbuilder/2009"
        alpha.disabledStates="0.5">
    <!-- states -->
    <s:states>
        <s:State name="up" />
        <s:State name="over" stateGroups="overStates" />
        <s:State name="down" stateGroups="downStates" />
        <s:State name="disabled" stateGroups="disabledStates" />
        <s:State name="upAndSelected" stateGroups="selectedStates" />
        <s:State name="overAndSelected" stateGroups="overStates, selectedStates" />
        <s:State name="downAndSelected" stateGroups="downStates, selectedStates" />
        <s:State name="disabledAndSelected" stateGroups="disabledStates, selectedStates" />
    </s:states>
 
    <fx:Metadata>
        [HostComponent("spark.components.CheckBox")]
    </fx:Metadata> 
 
    <fx:Script fb:purpose="styling">
        <![CDATA[
            /* Define the skin elements that should not be colorized. 
               For button, the graphics are colorized but the label is not. */
            static private const exclusions:Array = ["labelDisplay", "check"];
 
            override public function get colorizeExclusions():Array {
                return exclusions;
            }
 
            /* Define the symbol fill items that should be colored by the "symbolColor" style. */
            static private const symbols:Array = ["checkMarkFill"];
 
            override public function get symbolItems():Array {
                return symbols;
            }
 
            override protected function initializationComplete():void {
                useChromeColor = true;
                super.initializationComplete();
            }
        ]]>
    </fx:Script>
 
    <fx:Script>
        <![CDATA[
            private static const focusExclusions:Array = ["labelDisplay"];
 
            override public function get focusSkinExclusions():Array {
                return focusExclusions;
            }
        ]]>
    </fx:Script>
 
    <s:Group verticalCenter="0" width="13" height="13">
        <!-- drop shadow -->
        <s:Rect left="-1" top="-1" right="-1" bottom="-1">
            <s:stroke>
                <s:LinearGradientStroke rotation="90" weight="1">
                    <s:GradientEntry color="0x000000" 
                                   color.downStates="0xFFFFFF"
                                   alpha="0.011"
                                   alpha.downStates="0" />
                    <s:GradientEntry color="0x000000" 
                                   color.downStates="0xFFFFFF" 
                                   alpha="0.121"
                                   alpha.downStates="0.57" />
                </s:LinearGradientStroke>
            </s:stroke>
        </s:Rect>
 
        <!-- fill -->
        <s:Rect left="1" top="1" right="1" bottom="1">
            <s:fill>
                <s:LinearGradient rotation="90">
                    <s:GradientEntry color="0xFFFFFF" 
                                   color.overStates="0xBBBDBD" 
                                   color.downStates="0xAAAAAA" 
                                   alpha="0.85" />
                    <s:GradientEntry color="0xD8D8D8" 
                                   color.overStates="0x9FA0A1" 
                                   color.downStates="0x929496" 
                                   alpha="0.85" />
                </s:LinearGradient>
            </s:fill>
        </s:Rect>
 
        <!-- fill highlight -->
        <s:Rect left="1" right="1" top="1" height="5">
            <s:fill>
                <s:SolidColor color="0xFFFFFF" alpha="0.33" alpha.downStates="0" />
            </s:fill>
        </s:Rect>
 
        <!-- layer 6: highlight stroke (all states except down) -->
        <s:Rect left="1" right="1" top="1" bottom="1" excludeFrom="downStates">
            <s:stroke>
                <s:LinearGradientStroke rotation="90" weight="1">
                    <s:GradientEntry color="0xFFFFFF" alpha.overStates="0.33" />
                    <s:GradientEntry color="0xFFFFFF" alpha="0.12" alpha.overStates="0.0396" />
                </s:LinearGradientStroke>
            </s:stroke>
        </s:Rect>
 
        <!-- layer 6: highlight stroke (down state only) -->
        <s:Rect left="1" top="1" bottom="1" width="1" includeIn="downStates">
            <s:fill>
                <s:SolidColor color="0x000000" alpha="0.07" />
            </s:fill>
        </s:Rect>
        <s:Rect right="1" top="1" bottom="1" width="1" includeIn="downStates">
            <s:fill>
                <s:SolidColor color="0x000000" alpha="0.07" />
            </s:fill>
        </s:Rect>
        <s:Rect left="1" top="1" right="1" height="1" includeIn="downStates">
            <s:fill>
                <s:SolidColor color="0x000000" alpha="0.25" />
            </s:fill>
        </s:Rect>
        <s:Rect left="1" top="2" right="1" height="1" includeIn="downStates">
            <s:fill>
                <s:SolidColor color="0x000000" alpha="0.09" />
            </s:fill>
        </s:Rect>
 
        <!-- border - put on top of the fill so it doesn't disappear when scale is less than 1 -->
        <s:Rect left="0" top="0" right="0" bottom="0">
            <s:stroke>
                <s:LinearGradientStroke rotation="90" weight="1">
                    <s:GradientEntry color="0x000000" 
                                   alpha="0.5625"
                                   alpha.downStates="0.6375" />
                    <s:GradientEntry color="0x000000" 
                                   alpha="0.75"
                                   alpha.downStates="0.85" />
                </s:LinearGradientStroke>
            </s:stroke>
        </s:Rect>
 
        <!-- checkmark -->
        <!--- The checkmark in the box for this skin. To create a custom check mark, create a custom skin class. -->
        <s:Path id="check"
                left="2" top="0"
                includeIn="selectedStates"
                itemCreationPolicy="immediate"
                data="M 9.2 0.1 L 4.05 6.55 L 3.15 5.0 L 0.05 5.0 L 4.6 9.7 L 12.05 0.1 L 9.2 0.1">
            <s:fill>
                <s:SolidColor id="checkMarkFill"
                              color="0" alpha="0.8" />
            </s:fill>
        </s:Path>
    </s:Group>
 
    <!-- Label -->
    <s:Label id="labelDisplay"
             textAlign="start"
             verticalAlign="middle"
             maxDisplayedLines="-1"
             left="18" right="0" top="3" bottom="3"
             verticalCenter="2" />
 
</s:SparkSkin>

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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