Actionscript 3 防止Flex树丢弃反馈
我希望允许用户在Flex树文件夹中重新排序项目，但不将这些项目移到文件夹外。我可以阻止外部掉电成功，但我想（在掉电之前）给用户反馈掉电不会成功。我已经找到了很多关于删除操作的例子，但是没有任何东西能够向用户显示正确的反馈 根据树文档，我应该能够在Actionscript 3 防止Flex树丢弃反馈,actionscript-3,apache-flex,drag-and-drop,Actionscript 3,Apache Flex,Drag And Drop,我希望允许用户在Flex树文件夹中重新排序项目，但不将这些项目移到文件夹外。我可以阻止外部掉电成功，但我想（在掉电之前）给用户反馈掉电不会成功。我已经找到了很多关于删除操作的例子，但是没有任何东西能够向用户显示正确的反馈 根据树文档，我应该能够在dragOver事件期间调用DragManager.showFeedback（DragManager.NONE），但这不起作用。下面是一个简短的示例项目。是否有任何方法可以在拖动事件期间向用户指示拖放不会成功 提前感谢您提供的任何解决方案 <?xm
dragOverDragManager.showFeedback（DragManager.NONE）<?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"
width="354"
height="480">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.core.IUIComponent;
import mx.core.mx_internal;
import mx.events.DragEvent;
import mx.events.FlexEvent;
import mx.managers.DragManager;
protected function tree_dragEnterHandler(event:DragEvent):void {
// only items can be dragged - not folders
if (tree.selectedItem.@type == "item") {
DragManager.acceptDragDrop(IUIComponent(event.currentTarget));
} else {
event.preventDefault();
DragManager.showFeedback(DragManager.NONE);
}
}
protected function tree_dragOverHandler(event:DragEvent):void {
var dropData:Object = tree.mx_internal::_dropData;
var dragItem:XML = event.dragSource.dataForFormat("treeItems")[0];
if (!dropData || !dropData.parent || !dragItem.parent() || dragItem.parent() != dropData.parent) {
trace("preventing drop");
DragManager.showFeedback(DragManager.NONE);
return;
}
trace("allowing drop");
DragManager.showFeedback(DragManager.MOVE);
}
protected function tree_dragDropHandler(event:DragEvent):void {
}
]]>
</fx:Script>
<fx:Declarations>
<fx:XML id="treeData">
<folder id="root"
label="root"
type="root">
<folder id="folder1"
label="Folder 1"
type="folder">
<folder id="folder2"
label="Folder 2"
type="folder">
<item id="item1"
label="Item 1"
type="item"/>
<item id="item2"
label="Item 2"
type="item"/>
<item id="item3"
label="Item 3"
type="item"/>
<item id="item4"
label="Item 4"
type="item"/>
<item id="item5"
label="Item 5"
type="item"/>
</folder>
</folder>
<folder id="folder3"
label="Folder 3"
type="folder"/>
<folder id="folder4"
label="Folder 4"
type="folder"/>
<folder id="folder5"
label="Folder 5"
type="folder"/>
</folder>
</fx:XML>
</fx:Declarations>
<mx:Tree id="tree"
left="29"
right="28"
top="28"
bottom="27"
dragEnabled="true"
dropEnabled="true"
dragMoveEnabled="true"
dataProvider="{treeData}"
labelField="@label"
dragEnter="tree_dragEnterHandler(event)"
dragOver="tree_dragOverHandler(event)"
dragDrop="tree_dragDropHandler(event)"
showRoot="false">
</mx:Tree>
</s:WindowedApplication>
令人沮丧的是，默认的拖放功能几乎提供了实现这一点所需的一切，但还不够。看起来IlyaZ的答案应该有效，但这可能是Flex的mx:Tree控件中的一个bug 正如SunilD所提到的，我最终通过滚动自己的拖放实现实现了这一点。下面为将来可能遇到相同问题的任何人提供了代码 请注意，当用户在
maxDropIndexmaxDropIndex+1
maxDropIndex）{
跟踪（“防止跌落”）；
DragManager.showFeedback（DragManager.NONE）；
this.tree.hideDropFeedback（事件）；
返回；
}
跟踪（“允许下降”）；
DragManager.showFeedback（DragManager.MOVE）；
this.tree.showDropFeedback（事件）；
}
受保护的函数树\u dragDropHandler（事件：DragEvent）：无效{
跟踪（“dragDropHandler”）；
}
受保护的函数树\u mouseMoveHandler（事件：MouseEvent）：无效{
//看看我们是否应该开始拖动操作
如果（event.buttonDown&&！拖动&tree.selectedItem&&tree.selectedItem.@type==“item”）{
//TODO:根据当前选定的索引计算最小和最大阻力索引
minDropIndex=2；
maxDropIndex=7；
//开始拖动
拖动=真；
var dragSource:dragSource=new dragSource（）；
addData（tree.selectedItem，“tree\u item\u node”）；
doDrag（IUIComponent（event.currentTarget）、dragSource、event）；
}
}
受保护的函数树\u dragCompleteHandler（事件：DragEvent）：无效{
跟踪（“拖动完成：不再拖动”）；
this.tree.hideDropFeedback（事件）；
拖动=假；
}
]]>
<?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"
width="354"
height="480">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.core.DragSource;
import mx.core.IUIComponent;
import mx.core.mx_internal;
import mx.events.DragEvent;
import mx.events.FlexEvent;
import mx.managers.DragManager;
protected var dragging:Boolean = false;
protected var minDropIndex:int = 0;
protected var maxDropIndex:int = 0;
protected function tree_dragEnterHandler(event:DragEvent):void {
// only items can be dropped
if (event.dragSource.hasFormat("tree_item_node")) {
DragManager.acceptDragDrop(IUIComponent(event.currentTarget));
trace("accepting DragDrop");
} else {
event.preventDefault();
DragManager.showFeedback(DragManager.NONE);
trace("rejecting DragDrop");
}
}
protected function tree_dragOverHandler(event:DragEvent):void {
var index:int = tree.calculateDropIndex(event);
if (index < minDropIndex || index > maxDropIndex) {
trace("preventing drop");
DragManager.showFeedback(DragManager.NONE);
this.tree.hideDropFeedback(event);
return;
}
trace("allowing drop");
DragManager.showFeedback(DragManager.MOVE);
this.tree.showDropFeedback(event);
}
protected function tree_dragDropHandler(event:DragEvent):void {
trace("dragDropHandler");
}
protected function tree_mouseMoveHandler(event:MouseEvent):void {
// see if we should start a drag operation
if (event.buttonDown && !dragging && tree.selectedItem && tree.selectedItem.@type == "item") {
// TODO: calculate the min and max drag indices from currently-selected index
minDropIndex = 2;
maxDropIndex = 7;
// start the drag
dragging = true;
var dragSource:DragSource = new DragSource();
dragSource.addData(tree.selectedItem, "tree_item_node");
DragManager.doDrag(IUIComponent(event.currentTarget), dragSource, event);
}
}
protected function tree_dragCompleteHandler(event:DragEvent):void {
trace("dragComplete: no longer dragging");
this.tree.hideDropFeedback(event);
dragging = false;
}
]]>
</fx:Script>
<fx:Declarations>
<fx:XML id="treeData">
<folder id="root"
label="root"
type="root">
<folder id="folder1"
label="Folder 1"
type="folder">
<folder id="folder2"
label="Folder 2"
type="folder">
<item id="item1"
label="Item 1"
type="item"/>
<item id="item2"
label="Item 2"
type="item"/>
<item id="item3"
label="Item 3"
type="item"/>
<item id="item4"
label="Item 4"
type="item"/>
<item id="item5"
label="Item 5"
type="item"/>
</folder>
</folder>
<folder id="folder3"
label="Folder 3"
type="folder"/>
<folder id="folder4"
label="Folder 4"
type="folder"/>
<folder id="folder5"
label="Folder 5"
type="folder"/>
</folder>
</fx:XML>
</fx:Declarations>
<mx:Tree id="tree"
left="29"
right="28"
top="28"
bottom="27"
dragEnabled="false"
dropEnabled="false"
dataProvider="{treeData}"
labelField="@label"
dragEnter="tree_dragEnterHandler(event)"
dragOver="tree_dragOverHandler(event)"
dragDrop="tree_dragDropHandler(event)"
dragComplete="tree_dragCompleteHandler(event)"
mouseMove="tree_mouseMoveHandler(event)"
showRoot="false">
</mx:Tree>
</s:WindowedApplication>