我想在 AdvancedDataGrid 树结构上实现自定义拖动，它只允许在树枝（而不是叶子）上拖动。
我遇到了很多困难，尝试使用 MouseDown 事件，但没有运气！
好的，我想我已经让 mousedown 能够确定该项目是否是叶子的分支。有关如何使用高级数据网格执行自定义拖动的任何帮助？
var grid : AdvancedDataGrid = AdvancedDataGrid(event.currentTarget);
如果（grid.selectedItem.hasOwnProperty（“类别”）
&& grid.selectedItem.categories!=null) {
Alert.show("是");
}
否则 { Alert.show("no"); }
我尝试了许多不同的方法来做到这一点，这是我想出的最佳解决方案。AdvancedDataGrid 已经内置了处理 mouseMove/mouseOver/mouseDown 事件的逻辑，因此无需重新创建它。只需覆盖 DragEvent 处理程序。
我已经复制了我在几个需要类似功能的应用程序中使用的代码，包括确定是否可以拖动项目的逻辑，以及确定是否可以将其拖放到某个位置的一些逻辑。我还包括了广泛的评论，以帮助解释为什么要完成某些事情。我希望这有帮助！
CustomADG.as：
package
{
import mx.controls.AdvancedDataGrid;
import mx.controls.listClasses.IListItemRenderer;
import mx.core.DragSource;
import mx.events.DragEvent;
import mx.managers.DragManager;
import mx.utils.ObjectUtil;
public class DragDropADG extends AdvancedDataGrid
{
private var itemRendererUnderPoint:IListItemRenderer
public function DragDropADG()
{
super();
}
override protected function dragStartHandler(event:DragEvent):void
{
/* Create a new Array from the Array of selectedItems, filtering out items
that are not "branches". */
var selectedBranches:Array /* of Object */ =
selectedItems.filter(hasCategories);
function hasCategories(element:*, index:int, array:Array):Boolean
{
/* Returns true if the item is a Branch (has children in the categories
property). */
return (element.hasOwnProperty("categories") &&
element.categories != null);
}
/* Exit if no Branches are selected. This will stop the drag operation from
starting. */
if (selectedBranches.length == 0)
return;
/* Reset the selectedItems Array to include only selected Branches. This
will deselect any "non-Branch" items. */
selectedItems = selectedBranches;
/* Create a copy of the Array of selected indices to be sorted for
display in the drag proxy. */
var sortedSelectedIndices:Array /* of int */ =
ObjectUtil.copy(selectedIndices) as Array /* of int */;
// Sort the selected indices
sortedSelectedIndices.sort(Array.NUMERIC);
/* Create an new Array to store the selected Branch items sorted in the
order that they are displayed in the AdvancedDataGrid. */
var draggedBranches:Array = [];
var itemRendererAtIndex:IListItemRenderer;
for each (var index:int in sortedSelectedIndices)
{
itemRendererAtIndex = indexToItemRenderer(index);
var branchItem:Object = itemRendererAtIndex.data;
draggedBranches.push(branchItem);
}
// Create a new DragSource Object to store data about the Drag operation.
var dragSource:DragSource = new DragSource();
// Add the Array of Branches to be dragged to the DragSource Object.
dragSource.addData(draggedBranches, "draggedBranches");
// Create a new Container to serve as the Drag Proxy.
var dragProxy:DragProxyContainer = new DragProxyContainer();
/* Update the labels in the Drag Proxy using the "label" field of the items
being dragged. */
dragProxy.setLabelText(draggedBranches);
/* Create a point relative to this component from the mouse
cursor location (for the DragEvent). */
var eventPoint:Point = new Point(event.localX, event.localY);
// Initiate the Drag Event
DragManager.doDrag(this, dragSource, event, dragProxy,
-eventPoint.x, -eventPoint.y, 0.8);
}
/* This function runs when ANY item is dragged over any part of this
AdvancedDataGrid (even if the item is from another component). */
override protected function dragEnterHandler(event:DragEvent):void
{
/* If the item(s) being dragged does/do not contain dragged Branches,
it/they are being dragged from another component; exit the function to
prevent a drop from occurring. */
if (!event.dragSource.hasFormat("draggedBranches"))
return;
var dropIndex:int = calculateDropIndex(event);
/* Get the itemRenderer of the current drag target, to determine if the
drag target can accept a drop. */
var dropTargetItemRenderer:IListItemRenderer =
indexToItemRenderer(dropIndex);
/* If the item is being dragged where there is no itemRenderer, exit the
function, to prevent a drop from occurring. */
if (dropTargetItemRenderer == null)
return;
/* If the item is being dragged onto an itemRenderer with no data, exit the
function, to prevent a drop from occurring. */
if (dropTargetItemRenderer.data == null)
return;
/* Store the underlying item for the itemRenderer being dragged over, to
validate that it can be dropped there. */
var dragEnterItem:Object = dropTargetItemRenderer.data
if (!dragEnterItem.hasOwnProperty("categories")
return;
if (dragEnterItem.categories == null)
return;
var eventDragSource:DragSource = event.dragSource;
eventDragSource.addData(dragEnterItem, "dropTargetItem");
/* Add an dragDrop Event Listener to the itemRenderer so that the
necessary will run when it is dropped.*/
dropTargetItemRenderer.addEventListener(DragEvent.DRAG_DROP,
itemRenderer_dragDropHandler);
// Specify that the itemRenderer being dragged over can accept a drop.
DragManager.acceptDragDrop(dropTargetItemRenderer);
}
/* Perform any logic that you want to occur once the user drops the item. */
private function itemRenderer_dragDropHandler(event:DragEvent):void
{
var eventDragSource:DragSource = event.dragSource;
var dropTargetItem:Object =
eventDragSource.dataForFormat("dropTargetItem");
if (dropTargetItem == null)
return;
var draggedBranchesData:Object =
eventDragSource.dataForFormat("draggedBranches");
var draggedBranches:Array /* of Object */ =
draggedBranchesData as Array /* of Object */;
// Call any other functions to update your underlying data, etc.
}
}
}
DragProxyContainer.as：
package
{
import mx.containers.VBox;
import mx.core.UITextField;
[Bindable]
public class DragProxyContainer extends VBox
{
private var textField:UITextField = new UITextField();
public function DragProxyContainer()
{
super();
minWidth = 150;
addChild(textField);
}
public function setLabelText(items:Array, labelField:String = "label"):void
{
var labelText:String;
var numItems:int = items.length;
if (numItems > 1)
{
labelText = numItems.toString() + " items";
}
else
{
var firstItem:Object = items[0];
labelText = firstItem[labelField];
}
textField.text = labelText;
}
}
}
dragEnter()如果对象是叶子，您可以尝试处理事件以停止拖动。