Flex 4 Spark component Panel - Hide Title Bar - apache-flex

Question

I have used Spark panel to display the object inside a container. The panel and the inside elements are created dynamically. (using ActionScript). I need to remove the title bar of the panel in actionscript. When I tried to remove that, I am unable to hide the same.
Tried below ways.
Used style (classname) and set headerheight = 0.
Override the panel component and used the property this.titleBar.visible = false.
But not able to hide the titlebar.
I have used Panel spark component and Flash Builder 4.5 for development.
If there is any other way to achieve this, please let me know.

Answer 1

Your best bet is to create a custom skin and move the title bar pieces from the skin. It was very quick to put together a sample.
This is your custom skin; created as a copy of the PanelSkin with visual elements commented out.
<?xml version="1.0" encoding="utf-8"?>
<!--
ADOBE SYSTEMS INCORPORATED
Copyright 2008 Adobe Systems Incorporated
All Rights Reserved.
NOTICE: Adobe permits you to use, modify, and distribute this file
in accordance with the terms of the license agreement accompanying it.
-->
<!--- The default skin class for a Spark Panel container.
#see spark.components.Panel
#langversion 3.0
#playerversion Flash 10
#playerversion AIR 1.5
#productversion Flex 4
-->
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:fb="http://ns.adobe.com/flashbuilder/2009" blendMode="normal" mouseEnabled="false"
minWidth="131" minHeight="127" alpha.disabled="0.5" alpha.disabledWithControlBar="0.5">
<fx:Metadata>
<![CDATA[
/**
* #copy spark.skins.spark.ApplicationSkin#hostComponent
*/
[HostComponent("spark.components.Panel")]
]]>
</fx:Metadata>
<fx:Script fb:purpose="styling">
<![CDATA[
import mx.core.FlexVersion;
/* Define the skin elements that should not be colorized.
For panel, border and title background are skinned, but the content area, background, border, and title text are not. */
static private const exclusions:Array = ["background", "titleDisplay", "contentGroup", "controlBarGroup", "border"];
/* exclusions before Flex 4.5 for backwards-compatibility purposes */
static private const exclusions_4_0:Array = ["background", "titleDisplay", "contentGroup", "controlBarGroup"];
/**
* #private
*/
override public function get colorizeExclusions():Array
{
// Since border is styleable via borderColor, no need to allow chromeColor to affect
// the border. This is wrapped in a compatibility flag since this change was added
// in Flex 4.5
if (FlexVersion.compatibilityVersion < FlexVersion.VERSION_4_5)
{
return exclusions_4_0;
}
return exclusions;
}
/**
* #private
*/
override protected function initializationComplete():void
{
useChromeColor = true;
super.initializationComplete();
}
/**
* #private
*/
override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
{
if (getStyle("borderVisible") == true)
{
border.visible = true;
background.left = background.top = background.right = background.bottom = 1;
contents.left = contents.top = contents.right = contents.bottom = 1;
}
else
{
border.visible = false;
background.left = background.top = background.right = background.bottom = 0;
contents.left = contents.top = contents.right = contents.bottom = 0;
}
dropShadow.visible = getStyle("dropShadowVisible");
var cr:Number = getStyle("cornerRadius");
var withControls:Boolean =
(currentState == "disabledWithControlBar" ||
currentState == "normalWithControlBar");
if (cornerRadius != cr)
{
cornerRadius = cr;
dropShadow.tlRadius = cornerRadius;
dropShadow.trRadius = cornerRadius;
dropShadow.blRadius = withControls ? cornerRadius : 0;
dropShadow.brRadius = withControls ? cornerRadius : 0;
setPartCornerRadii(topMaskRect, withControls);
setPartCornerRadii(border, withControls);
setPartCornerRadii(background, withControls);
}
if (bottomMaskRect) setPartCornerRadii(bottomMaskRect, withControls);
borderStroke.color = getStyle("borderColor");
borderStroke.alpha = getStyle("borderAlpha");
backgroundFill.color = getStyle("backgroundColor");
backgroundFill.alpha = getStyle("backgroundAlpha");
super.updateDisplayList(unscaledWidth, unscaledHeight);
}
/**
* #private
*/
private function setPartCornerRadii(target:Rect, includeBottom:Boolean):void
{
target.topLeftRadiusX = cornerRadius;
target.topRightRadiusX = cornerRadius;
target.bottomLeftRadiusX = includeBottom ? cornerRadius : 0;
target.bottomRightRadiusX = includeBottom ? cornerRadius : 0;
}
private var cornerRadius:Number;
]]>
</fx:Script>
<s:states>
<s:State name="normal" />
<s:State name="disabled" />
<s:State name="normalWithControlBar" stateGroups="withControls" />
<s:State name="disabledWithControlBar" stateGroups="withControls" />
</s:states>
<!-- drop shadow can't be hittable so it stays sibling of other graphics -->
<!--- #private -->
<s:RectangularDropShadow id="dropShadow" blurX="20" blurY="20" alpha="0.32" distance="11"
angle="90" color="#000000" left="0" top="0" right="0" bottom="0"/>
<!-- drop shadow can't be hittable so all other graphics go in this group -->
<s:Group left="0" right="0" top="0" bottom="0">
<!-- top group mask -->
<!--- #private -->
<s:Group left="1" top="1" right="1" bottom="1" id="topGroupMask" >
<!--- #private -->
<s:Rect id="topMaskRect" left="0" top="0" right="0" bottom="0">
<s:fill>
<s:SolidColor alpha="0"/>
</s:fill>
</s:Rect>
</s:Group>
<!-- bottom group mask -->
<!--- #private -->
<s:Group left="1" top="1" right="1" bottom="1" id="bottomGroupMask"
includeIn="normalWithControlBar, disabledWithControlBar">
<!--- #private -->
<s:Rect id="bottomMaskRect" left="0" top="0" right="0" bottom="0">
<s:fill>
<s:SolidColor alpha="0"/>
</s:fill>
</s:Rect>
</s:Group>
<!-- layer 1: border -->
<!--- #private -->
<s:Rect id="border" left="0" right="0" top="0" bottom="0" >
<s:stroke>
<!--- #private -->
<s:SolidColorStroke id="borderStroke" weight="1" />
</s:stroke>
</s:Rect>
<!-- layer 2: background fill -->
<!--- Defines the appearance of the PanelSkin class's background. -->
<s:Rect id="background" left="1" top="1" right="1" bottom="1">
<s:fill>
<!--- #private
Defines the PanelSkin class's background fill. The default color is 0xFFFFFF. -->
<s:SolidColor id="backgroundFill" color="#FFFFFF"/>
</s:fill>
</s:Rect>
<!-- layer 3: contents -->
<!--- Contains the vertical stack of titlebar content and controlbar. -->
<s:Group left="1" right="1" top="1" bottom="1" id="contents">
<s:layout>
<s:VerticalLayout gap="0" horizontalAlign="justify" />
</s:layout>
<!--- #private -->
<!-- <s:Group id="topGroup" mask="{topGroupMask}">
-->
<!-- layer 0: title bar fill -->
<!--- #private -->
<!-- <s:Rect id="tbFill" left="0" right="0" top="0" bottom="1">
<s:fill>
<s:LinearGradient rotation="90">
<s:GradientEntry color="0xE2E2E2" />
<s:GradientEntry color="0xD9D9D9" />
</s:LinearGradient>
</s:fill>
</s:Rect>
-->
<!-- layer 1: title bar highlight -->
<!--- #private -->
<!-- <s:Rect id="tbHilite" left="0" right="0" top="0" bottom="0">
<s:stroke>
<s:LinearGradientStroke rotation="90" weight="1">
<s:GradientEntry color="0xEAEAEA" />
<s:GradientEntry color="0xD9D9D9" />
</s:LinearGradientStroke>
</s:stroke>
</s:Rect>
-->
<!-- layer 2: title bar divider -->
<!--- #private -->
<!-- <s:Rect id="tbDiv" left="0" right="0" height="1" bottom="0">
<s:fill>
<s:SolidColor color="0xC0C0C0" />
</s:fill>
</s:Rect>
-->
<!-- layer 3: text -->
<!--- #copy spark.components.Panel#titleDisplay -->
<!-- <s:Label id="titleDisplay" maxDisplayedLines="1"
left="9" right="3" top="1" bottom="0" minHeight="30"
verticalAlign="middle" textAlign="start" fontWeight="bold">
</s:Label>
-->
<!-- </s:Group>
-->
<!--
Note: setting the minimum size to 0 here so that changes to the host component's
size will not be thwarted by this skin part's minimum size. This is a compromise,
more about it here: http://bugs.adobe.com/jira/browse/SDK-21143
-->
<!--- #copy spark.components.SkinnableContainer#contentGroup -->
<s:Group id="contentGroup" width="100%" height="100%" minWidth="0" minHeight="0">
</s:Group>
<!--- #private -->
<s:Group id="bottomGroup" minWidth="0" minHeight="0"
includeIn="normalWithControlBar, disabledWithControlBar" >
<s:Group left="0" right="0" top="0" bottom="0" mask="{bottomGroupMask}">
<!-- layer 0: control bar divider line -->
<s:Rect left="0" right="0" top="0" height="1" alpha="0.22">
<s:fill>
<s:SolidColor color="0x000000" />
</s:fill>
</s:Rect>
<!-- layer 1: control bar highlight -->
<s:Rect left="0" right="0" top="1" bottom="0">
<s:stroke>
<s:LinearGradientStroke rotation="90" weight="1">
<s:GradientEntry color="0xE5E5E5" />
<s:GradientEntry color="0xD8D8D8" />
</s:LinearGradientStroke>
</s:stroke>
</s:Rect>
<!-- layer 2: control bar fill -->
<s:Rect left="1" right="1" top="2" bottom="1">
<s:fill>
<s:LinearGradient rotation="90">
<s:GradientEntry color="0xDADADA" />
<s:GradientEntry color="0xC5C5C5" />
</s:LinearGradient>
</s:fill>
</s:Rect>
</s:Group>
<!-- layer 3: control bar -->
<!--- #copy spark.components.Panel#controlBarGroup -->
<s:Group id="controlBarGroup" left="0" right="0" top="1" bottom="1" minWidth="0" minHeight="0">
<s:layout>
<s:HorizontalLayout paddingLeft="10" paddingRight="10" paddingTop="7" paddingBottom="7" gap="10" />
</s:layout>
</s:Group>
</s:Group>
</s:Group>
</s:Group>
</s:SparkSkin>
And this is the app:
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx">
<fx:Declarations>
<!-- Place non-visual elements (e.g., services, value objects) here -->
</fx:Declarations>
<s:VGroup>
<s:Panel />
<s:Panel skinClass="PanelNoTitleBar"/>
</s:VGroup>
</s:WindowedApplication>
The first panel will display the original skin; the second panel displays the custom skin; with no title bar.

Answer 2

Skinning is the common advice, and apparently that is the intended design. The other answer does a fine job of showing this method.
However, there is also a nice subclassing solution on a related question: Flex 4 spark Panel has an ugly gray top part. That may be enough if you only want to remove the title bar.