[英]Is it possible to make an item in a Flex List control not selectable?
是否可以使List控件中的項目無法選擇? 如果是這樣,將如何實現?
到目前為止,我已經嘗試過一件事。 我所做的是使用一個自定義項目渲染器,該渲染器在FlexEvent.DATA_CHANGE事件發生時檢查data屬性中的值。 如果未設置該值,則嘗試將項目渲染器的selectable屬性設置為false。 不幸的是,這似乎不起作用。
有任何想法嗎?
所以我想到了自己的解決方案。 它與您的相似,並且似乎可以達到目的,並且涵蓋了除破解上一頁和下一頁鍵之外的所有基礎。 我說hack,是因為我不確定它是否可以像List控件一樣處理caretIndex的增加或減少。 基本上,它只是手動將caretIndex設置為下一個可選項目之前的索引,並將鍵碼更改為簡單的上移或下移。
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;
}
通過分別在caretIndex ++和caretIndex之前分別執行verticalScrollPosition ++和verticalScrollPosition(在Michael上面鏈接的示例中),我能夠解決第一個/最后一個項目不可選擇的問題。 我簡直不敢相信修復如此簡單,但是確實如此!
我一直在尋找解決方案,這是我想出的解決方案。 請注意,我正在使用火花列表。 我希望有人覺得這有幫助。
示例:從我的實現中抄襲而來,在該實現中我構建自己的項目並使用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示例添加一個分隔器組件。 這是一個示例,其中剝離了渲染器邏輯,並保留了選擇邏輯:
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),可更好地處理可滾動列表和連續的分隔符:
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;
}
只是以為我會補充我的兩種意思。 我在想同樣的事情(如何將列表設置為不可選擇),我意識到spark組件數據組可以做到這一點。 當然,您需要使用flex 4,但是如果您願意,並且想知道我是否可以將列表設置為不可選擇,那么建議您使用數據組。
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