Question

I wonder how to achieve this in Flex.

Basically, I have enabled Drag and Drop in some of my list controls.

<mx:DataGrid id="dg1" width="100%" height="100%" dataProvider="{xmllcData}"   
             dropEnabled="true" dragDrop="dg1_dragDropHandler(event)">
</mx:DataGrid>

In the function dg1_dragDropHandler event, I have the following codes:

private function dg1_dragDropHandler(evt:DragEvent):void
{
  // Perform some actions here...
  // .......

  // Show Message to Confirm.
Alert.show('Proceed?', 'Title', Alert.YES | Alert.NO, null, handleAlert, null, Alert.YES);
}

private function handleAlert(evt:CloseEvent):void 
{
  if (evt.detail == Alert.YES)
{
    // Perform the functions as necessary
}
else
{
    // Execute the script to prevent the dropping of the object.
    // How can I call the DragEvent.preventDefault(); function from here?
}

}

In the codes above, I want to call the preventDefault() on the alertHandler function since the other scripts after the call to the Alert.show in dg1_dragDropHandler event would be executed concurrently with the alert.show.

How would I be able to reference the DragEvent of the dg1_dragDropHandler event from the alertHandler event?

Answer 1

Instead of specifiying your listener function, handleAlert(), as a normal function, you can use an anonymous function. Write your code like this:

private function dg1_dragDropHandler(evt:DragEvent):void
   {
   // Perform some actions here...
   // .......

   // Show Message to Confirm.
   Alert.show('Proceed?', 'Title', 
               Alert.YES | Alert.NO, 
               null, 
               function(evt:CloseEvent) {
                     if (evt.detail == Alert.YES) {
                        // Perform the functions as necessary
                     }
                     else {
                      // Execute the script to prevent the dropping of the object.
                      // Now you have access to the evt:DragEvent!
                     }
                },
                null, Alert.YES);
             }
     }

When you use an anonymous function, you still have access to all the variables in your current scope. This means you can still access the evt:DragEvent variable. As Glenn said though, I don’t know if this will solve your default action problem.