[英]Is it possible to make an item in a Flex List control not selectable?
是否可以使List控件中的项目无法选择? 如果是这样,将如何实现?
到目前为止,我已经尝试过一件事。 我所做的是使用一个自定义项目渲染器,该渲染器在FlexEvent.DATA_CHANGE事件发生时检查data属性中的值。 如果未设置该值,则尝试将项目渲染器的selectable属性设置为false。 不幸的是,这似乎不起作用。
有任何想法吗?
所以我想到了自己的解决方案。 它与您的相似,并且似乎可以达到目的,并且涵盖了除破解上一页和下一页键之外的所有基础。 我说hack,是因为我不确定它是否可以像List控件一样处理caretIndex的增加或减少。 基本上,它只是手动将caretIndex设置为下一个可选项目之前的索引,并将键码更改为简单的上移或下移。
protected function disabledFilterFunction( data:Object ):Boolean
{
return ( data != null && data.data == null );
}
override protected function mouseEventToItemRenderer( event:MouseEvent ):IListItemRenderer
{
var item:IListItemRenderer = super.mouseEventToItemRenderer( event );
if( item && item.data && disabledFilterFunction( item.data ) )
return null;
return item;
}
override protected function moveSelectionVertically( code:uint, shiftKey:Boolean, ctrlKey:Boolean ):void
{
var i:int;
var newIndex:int;
switch( code )
{
case Keyboard.UP:
newIndex = getPreviousUnselectableIndex( caretIndex - 1 );
break;
case Keyboard.DOWN:
newIndex = getNextUnselectableIndex( caretIndex + 1 );
break;
case Keyboard.HOME:
newIndex = getFirstSelectableIndex();
code = Keyboard.UP;
break;
case Keyboard.END:
newIndex = getLastSelectableIndex();
code = Keyboard.DOWN;
break;
case Keyboard.PAGE_UP:
{
newIndex = Math.max( getFirstSelectableIndex(), getPreviousUnselectableIndex( caretIndex - ( rowCount - 2 ) ) );
code = Keyboard.UP;
break;
}
case Keyboard.PAGE_DOWN:
{
newIndex = Math.min( getLastSelectableIndex(), getNextUnselectableIndex( caretIndex + ( rowCount - 1 ) ) );
code = Keyboard.DOWN;
break;
}
}
if( newIndex > -1 && newIndex < collection.length )
{
caretIndex = newIndex;
super.moveSelectionVertically( code, shiftKey, ctrlKey );
}
}
private function getFirstSelectableIndex():int
{
var result:int = -1;
for( var i:int = 0; i < collection.length; i++ )
{
if( !disabledFilterFunction( collection[i] ) )
{
result = i + 1;
break;
}
}
return result;
}
private function getLastSelectableIndex():int
{
var result:int = -1;
for( var i:int = collection.length - 1; i > -1; i-- )
{
if( !disabledFilterFunction( collection[i] ) )
{
result = i - 1;
break;
}
}
return result;
}
private function getPreviousUnselectableIndex( startIndex:int ):int
{
var result:int = -1;
for( var i:int = startIndex; i > -1; i-- )
{
if( !disabledFilterFunction( collection[i] ) )
{
result = i + 1;
break;
}
}
return result;
}
private function getNextUnselectableIndex( startIndex:int ):int
{
var result:int = collection.length;
for( var i:int = startIndex; i < collection.length; i++ )
{
if( !disabledFilterFunction( collection[i] ) )
{
result = i - 1;
break;
}
}
return result;
}
通过分别在caretIndex ++和caretIndex之前分别执行verticalScrollPosition ++和verticalScrollPosition(在Michael上面链接的示例中),我能够解决第一个/最后一个项目不可选择的问题。 我简直不敢相信修复如此简单,但是确实如此!
我一直在寻找解决方案,这是我想出的解决方案。 请注意,我正在使用火花列表。 我希望有人觉得这有帮助。
示例:从我的实现中抄袭而来,在该实现中我构建自己的项目并使用Tile Layout
<s:List id="myListView"
itemRenderer="spark.skins.spark.DefaultComplexItemRenderer"
horizontalCenter="0"
verticalCenter="0"
borderVisible="false"
dataProvider="{myItems}"
change="changeHandler(event)" changing="changingHandler(event)"
requireSelection="false"
selectedIndex="-1" >
<s:layout>
<s:TileLayout verticalGap="0" />
</s:layout>
</s:List>
<fx:script>
<![CDATA[
import mx.collections.ArrayCollection;
import spark.events.IndexChangeEvent;
[Bindable]
public var myItems = new ArrayCollection;
protected function startup():void {
// Here's where you'd build up your items if they
// need to be built dynamically.
}
protected function changeHandler(event:IndexChangeEvent):void
{
var currentIndx:int = event.currentTarget.selectedIndex;
var selectedItem:UIComponent = event.currentTarget.selectedItem as UIComponent;
// Do whatever you need to do on selection here
}
protected function canMicrophoneChange(event:IndexChangeEvent):void
{
var currentIndx:int = event.currentTarget.selectedIndex;
var selectedItem:UIComponent = event.currentTarget.selectedItem as UIComponent;
// This will cancel the select if the item was not enabled.
if (selectedItem.enabled == false) event.preventDefault();
}
]]>
</fx:script>
我可以按照此ComboBox示例添加一个分隔器组件。 这是一个示例,其中剥离了渲染器逻辑,并保留了选择逻辑:
package com.example.ui {
import flash.events.MouseEvent;
import flash.ui.Keyboard;
import mx.controls.List;
import mx.controls.listClasses.IListItemRenderer;
public class MyList extends List
{
public function MyList()
{
super();
}
/** Override mouse navigation */
protected override function mouseEventToItemRenderer(event:MouseEvent):IListItemRenderer {
var row:IListItemRenderer = super.mouseEventToItemRenderer(event);
if (row != null && isSelectable(row.data)) {
return null;
}
return row;
}
/** Override keyboard navigation */
protected override function moveSelectionVertically(code:uint, shiftKey:Boolean, ctrlKey:Boolean):void {
super.moveSelectionVertically(code, shiftKey, ctrlKey);
if (code == Keyboard.DOWN && isSeparatorData(selectedItem)) {
caretIndex++;
}
if (code == Keyboard.UP && isSeparatorData(selectedItem)) {
caretIndex--;
}
finishKeySelection();
}
/**
* Define this mechanism in a way that makes sense for your project.
*/
protected function isSelectable(data:Object):Boolean {
return data != null && data.hasOwnProperty("type") && data.type == "separator";
}
}
}
替代方法(仍然不完善),可更好地处理可滚动列表和连续的分隔符:
protected override function moveSelectionVertically(code:uint, shiftKey:Boolean, ctrlKey:Boolean):void {
super.moveSelectionVertically(code, shiftKey, ctrlKey);
var newCode:uint = singleLineCode(code);
var item:Object = selectedItem;
var itemChanged:Boolean = true;
while (!isNaN(newCode) && itemChanged && isSeparatorData(item)) {
super.moveSelectionVertically(newCode, shiftKey, ctrlKey);
itemChanged = (item === selectedItem);
item = selectedItem;
}
}
private function singleLineCode(code:uint):uint {
switch (code) {
case Keyboard.UP:
case Keyboard.PAGE_UP:
return Keyboard.UP;
break;
case Keyboard.DOWN:
case Keyboard.PAGE_DOWN:
return Keyboard.DOWN;
break;
default:
return NaN;
break;
}
return code;
}
只是以为我会补充我的两种意思。 我在想同样的事情(如何将列表设置为不可选择),我意识到spark组件数据组可以做到这一点。 当然,您需要使用flex 4,但是如果您愿意,并且想知道我是否可以将列表设置为不可选择,那么建议您使用数据组。
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