How can you display a multi-line column header using the Flex Spark Data Grid?
How can you display a multi-line column header using the Flex Spark Data Grid for Flex 4.5?
Answer
To expand upon Constantiner's answer, you'll have to create a custom HeaderRenderer and set the Label's maxDisplayedLines to 2. Here's a sample renderer I found:
MyRenderer.mxml
<?xml version="1.0" encoding="utf-8"?>
<!--
ADOBE SYSTEMS INCORPORATED
Copyright 2010 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 DefaultGridHeaderRenderer class defines the default header renderer
for the columns of a Spark DataGrid control.
<p>Subclasses defined in MXML can redefine the values of the <code>labelDisplay</code>
and <code>sortIndicator</code> properties.</p>
@see spark.components.DataGrid
@see spark.components.GridColumnHeaderGroup
@see spark.components.gridClasses.GridItemRenderer
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 2.0
@productversion Flex 4.5
-->
<s:GridItemRenderer minWidth="21" minHeight="21"
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>
<!--- The default value of the <code>sortIndicator</code> property.
It must be an IFactory for an IVisualElement.
<p>This value is specified in a <code>fx:Declaration</code> block and can be overridden
by a declaration with <code>id="defaultSortIndicator"</code>
in an MXML subclass.</p>
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 2.0
@productversion Flex 4.5
-->
<fx:Component id="defaultSortIndicator">
<s:Path data="M 3.5 7.0 L 0.0 0.0 L 7.0 0.0 L 3.5 7.0" implements="spark.components.gridClasses.IGridVisualElement">
<fx:Script>
<![CDATA[
import spark.components.DataGrid;
import spark.components.Grid;
/**
* @private
*/
public function prepareGridVisualElement(grid:Grid, rowIndex:int, columnIndex:int):void
{
const dataGrid:DataGrid = grid.dataGrid;
if (!dataGrid)
return;
const color:uint = dataGrid.getStyle("symbolColor");
arrowFill1.color = color;
arrowFill2.color = color;
}
]]>
</fx:Script>
<s:fill>
<s:RadialGradient rotation="90" focalPointRatio="1">
<!--- @private -->
<s:GradientEntry id="arrowFill1" color="0" alpha="0.6" />
<!--- @private -->
<s:GradientEntry id="arrowFill2" color="0" alpha="0.8" />
</s:RadialGradient>
</s:fill>
</s:Path>
</fx:Component>
<!--- Displays the renderer's label property, which is set to the column's <code>headerText</code>.
It must be an instance of a <code>TextBase</code>, like <code>s:Label</code>.
<p>This visual element is added to the <code>labelDisplayGroup</code> by the renderer's
<code>prepare()</code> method. Any size/location constraints specified by the labelDisplay
define its location relative to the labelDisplayGroup.</p>
<p>This value is specified with a <code>fx:Declaration</code> and can be overridden
by a declaration with <code>id="labelDisplay"</code>
in an MXML subclass.</p>
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 2.0
@productversion Flex 4.5
-->
<s:Label id="labelDisplay"
verticalCenter="1" left="0" right="0" top="0" bottom="0"
textAlign="start"
fontWeight="bold"
verticalAlign="middle"
maxDisplayedLines="2"
showTruncationTip="true" />
</fx:Declarations>
<fx:Script>
<![CDATA[
import spark.components.gridClasses.IGridVisualElement;
import mx.core.IVisualElement;
import spark.components.DataGrid;
import spark.components.GridColumnHeaderGroup;
import spark.components.gridClasses.GridColumn;
/**
* @private
*/
private function dispatchChangeEvent(type:String):void
{
if (hasEventListener(type))
dispatchEvent(new Event(type));
}
//----------------------------------
// maxDisplayedLines
//----------------------------------
private var _maxDisplayedLines:int = 1;
[Bindable("maxDisplayedLinesChanged")]
[Inspectable(minValue="-1")]
/**
* The value of this property is used to initialize the
* <code>maxDisplayedLines</code> property of this renderer's
* <code>labelDisplay</code> element.
*
* @copy spark.components.supportClasses.TextBase#maxDisplayedLines
*
* @default 1
*
* @langversion 3.0
* @playerversion Flash 10
* @playerversion AIR 1.5
* @productversion Flex 4.5
*/
public function get maxDisplayedLines():int
{
return _maxDisplayedLines;
}
/**
* @private
*/
public function set maxDisplayedLines(value:int):void
{
if (value == _maxDisplayedLines)
return;
_maxDisplayedLines = value;
if (labelDisplay)
labelDisplay.maxDisplayedLines = value;
invalidateSize();
invalidateDisplayList();
dispatchChangeEvent("maxDisplayedLinesChanged");
}
//----------------------------------
// sortIndicator
//----------------------------------
private var _sortIndicator:IFactory;
private var sortIndicatorInstance:IVisualElement;
[Bindable("sortIndicatorChanged")]
/**
* A visual element that's displayed when the column is sorted.
*
* <p>The sortIndicator visual element is added to the <code>sortIndicatorGroup</code>
* by this renderer's <code>prepare()</code> method. Any size/location constraints
* specified by the sortIndicator define its location relative to the sortIndicatorGroup.</p>
*
* @default null
*
* @langversion 3.0
* @playerversion Flash 10
* @playerversion AIR 1.5
* @productversion Flex 4.5
*/
public function get sortIndicator():IFactory
{
return (_sortIndicator) ? _sortIndicator : defaultSortIndicator;
}
/**
* @private
*/
public function set sortIndicator(value:IFactory):void
{
if (_sortIndicator == value)
return;
_sortIndicator = value;
if (sortIndicatorInstance)
{
sortIndicatorGroup.includeInLayout = false;
sortIndicatorGroup.removeElement(sortIndicatorInstance);
sortIndicatorInstance = null;
}
invalidateDisplayList();
dispatchChangeEvent("sortIndicatorChanged");
}
/**
* @private
* Create and add the sortIndicator to the sortIndicatorGroup and the
* labelDisplay into the labelDisplayGroup.
*/
override public function prepare(hasBeenRecycled:Boolean):void
{
super.prepare(hasBeenRecycled);
if (labelDisplay && labelDisplayGroup && (labelDisplay.parent != labelDisplayGroup))
{
labelDisplayGroup.removeAllElements();
labelDisplayGroup.addElement(labelDisplay);
}
const column:GridColumn = this.column;
if (sortIndicator && column && column.grid && column.grid.dataGrid && column.grid.dataGrid.columnHeaderGroup)
{
const dataGrid:DataGrid = column.grid.dataGrid;
const columnHeaderGroup:GridColumnHeaderGroup = dataGrid.columnHeaderGroup;
if (columnHeaderGroup.isSortIndicatorVisible(column.columnIndex))
{
if (!sortIndicatorInstance)
{
sortIndicatorInstance = sortIndicator.newInstance();
sortIndicatorGroup.addElement(sortIndicatorInstance);
}
// Initialize sortIndicator
sortIndicatorInstance.visible = true;
const gridVisualElement:IGridVisualElement = sortIndicatorInstance as IGridVisualElement;
if (gridVisualElement)
gridVisualElement.prepareGridVisualElement(column.grid, -1, column.columnIndex);
sortIndicatorGroup.includeInLayout = true;
sortIndicatorGroup.scaleY = (column.sortDescending) ? 1 : -1;
}
else
{
if (sortIndicatorInstance)
{
sortIndicatorGroup.removeElement(sortIndicatorInstance);
sortIndicatorGroup.includeInLayout = false;
sortIndicatorInstance = null;
}
}
}
}
]]>
</fx:Script>
<s:states>
<s:State name="normal" />
<s:State name="hovered" />
<s:State name="down" />
</s:states>
<!-- layer 1: shadow -->
<!--- @private -->
<s:Rect id="shadow" left="-1" right="-1" top="-1" bottom="-1" radiusX="2">
<s:fill>
<s:LinearGradient rotation="90">
<s:GradientEntry color="0x000000"
color.down="0xFFFFFF"
alpha="0.01"
alpha.down="0" />
<s:GradientEntry color="0x000000"
color.down="0xFFFFFF"
alpha="0.07"
alpha.down="0.5" />
</s:LinearGradient>
</s:fill>
</s:Rect>
<!-- layer 2: fill -->
<!--- @private -->
<s:Rect id="fill" left="0" right="0" top="0" bottom="0">
<s:fill>
<s:LinearGradient rotation="90">
<s:GradientEntry color="0xFFFFFF"
color.hovered="0xBBBDBD"
color.down="0xAAAAAA"
alpha="0.85" />
<s:GradientEntry color="0xD8D8D8"
color.hovered="0x9FA0A1"
color.down="0x929496"
alpha="0.85" />
</s:LinearGradient>
</s:fill>
</s:Rect>
<!-- layer 3: fill lowlight -->
<!--- @private -->
<s:Rect id="lowlight" left="0" right="0" top="0" bottom="0">
<s:fill>
<s:LinearGradient rotation="270">
<s:GradientEntry color="0x000000" ratio="0.0" alpha="0.0627" />
<s:GradientEntry color="0x000000" ratio="0.48" alpha="0.0099" />
<s:GradientEntry color="0x000000" ratio="0.48001" alpha="0" />
</s:LinearGradient>
</s:fill>
</s:Rect>
<!-- layer 4: fill highlight -->
<!--- @private -->
<s:Rect id="highlight" left="0" right="0" top="0" bottom="0">
<s:fill>
<s:LinearGradient rotation="90">
<s:GradientEntry color="0xFFFFFF"
ratio="0.0"
alpha="0.33"
alpha.hovered="0.22"
alpha.down="0.12"/>
<s:GradientEntry color="0xFFFFFF"
ratio="0.48"
alpha="0.33"
alpha.hovered="0.22"
alpha.down="0.12" />
<s:GradientEntry color="0xFFFFFF"
ratio="0.48001"
alpha="0" />
</s:LinearGradient>
</s:fill>
</s:Rect>
<!-- layer 5: highlight stroke (all states except down) -->
<!--- @private -->
<s:Rect id="highlightStroke" left="0" right="0" top="0" bottom="0" excludeFrom="down">
<s:stroke>
<s:LinearGradientStroke rotation="90" weight="1">
<s:GradientEntry color="0xFFFFFF" alpha.hovered="0.22" />
<s:GradientEntry color="0xD8D8D8" alpha.hovered="0.22" />
</s:LinearGradientStroke>
</s:stroke>
</s:Rect>
<!-- layer 6: highlight stroke (down state only) -->
<!--- @private -->
<s:Rect id="hldownstroke1" left="0" right="0" top="0" bottom="0" includeIn="down">
<s:stroke>
<s:LinearGradientStroke rotation="90" weight="1">
<s:GradientEntry color="0x000000" alpha="0.25" ratio="0.0" />
<s:GradientEntry color="0x000000" alpha="0.25" ratio="0.001" />
<s:GradientEntry color="0x000000" alpha="0.07" ratio="0.0011" />
<s:GradientEntry color="0x000000" alpha="0.07" ratio="0.965" />
<s:GradientEntry color="0x000000" alpha="0.00" ratio="0.9651" />
</s:LinearGradientStroke>
</s:stroke>
</s:Rect>
<!--- @private -->
<s:Rect id="hldownstroke2" left="1" right="1" top="1" bottom="1" includeIn="down">
<s:stroke>
<s:LinearGradientStroke rotation="90" weight="1">
<s:GradientEntry color="0x000000" alpha="0.09" ratio="0.0" />
<s:GradientEntry color="0x000000" alpha="0.00" ratio="0.0001" />
</s:LinearGradientStroke>
</s:stroke>
</s:Rect>
<s:HGroup left="7" right="7" top="5" bottom="5" gap="8" verticalAlign="middle">
<s:BitmapImage source="54.gif" />
<!-- layer 7: Container for labelDisplay:TextBase -->
<!--- Defines the size and location of the labelDisplay visual element.
<p>The <code>labelDisplay</code> is added to this Group by the renderer's
<code>prepare()</code> method. Any size/location constraints
specified by the labelDisplay
define its layout relative to the labelDisplayGroup.</p>
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 2.0
@productversion Flex 4.5
-->
<s:Group id="labelDisplayGroup" width="100%" />
<!-- layer 8: Container for sortIndicator:IVisualElement -->
<!--- Defines the size and location of the sortIndicator visual element.
<p>The <code>sortIndicator</code> is added to this Group by the renderer's
<code>prepare()</code> method. Any size/location constraints specified
by the sortIndicator
define its layout relative to the sortIndicatorGroup. This Group is only
included in the layout when the sortIndicator is visible.</p>
@langversion 3.0
@playerversion Flash 10
@playerversion AIR 2.0
@productversion Flex 4.5
-->
<s:Group id="sortIndicatorGroup" includeInLayout="false" />
</s:HGroup>
</s:GridItemRenderer>
And then to use it in your DataGrid, just follow Constantiner's example:
<s:DataGrid>
<s:columns>
<s:ArrayList>
<s:GridColumn headerRenderer="MyRenderer" />
</s:ArrayList>
</s:columns>
</s:DataGrid>