[jbosstools-issues] [JBoss JIRA] Commented: (JBIDE-3608) DND support in CNF-based Servers View

[Rob Stryker (JIRA)]

    [ https://jira.jboss.org/jira/browse/JBIDE-3608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12449143#action_12449143 ] 

Rob Stryker commented on JBIDE-3608:
------------------------------------

Background:  
   CNF-based drag and drop support is pretty solid, however the API has a restriction that 1) any drop target must be an approved target (listed in plugin.xml) , and 2) the dragged item must be an "acceptable child".  

The "acceptable child" paradigm in CNF is for efficiency purposes. If each extender declares what kind of children they'll have, the framework can more accurately figure out for search / reveal / etc purposes what it's top-most parent most likely is.   However, this is unneccessary and undesirable for a drag-and-drop scenerio as the dragged item might be unacceptable but the drop action may be able to convert it properly into something it *can* have as a child. 

Eclipse bugs:
   https://bugs.eclipse.org/bugs/show_bug.cgi?id=261506
   https://bugs.eclipse.org/bugs/show_bug.cgi?id=261606
   https://bugs.eclipse.org/bugs/show_bug.cgi?id=261865

The fix:
   The fix was to override the dnd portion of CNF.  In the current release that cannot be done by overriding the DND service (which would be the optimal way to do it) because of restrictive field access and subclassing requirements. So instead I had to override the initDragAndDrop of the CommonViewer and replace the DropAdapter with one of my own.   My custom DropAdapter acted just like the CommonDropAdapter, except I couldn't subclass CommonDropAdapter because the class was final.  This would have been ok, except the extension points where further contributers declare their drop assistants REQUIRES a CommonDropAdapter.

In this way, anyone extending the JBossServersView via CNF API's to add Drop extensions must be aware that though the API for CommonDropAdapterAssistant declares the following method:

	public abstract IStatus handleDrop(CommonDropAdapter aDropAdapter,
			DropTargetEvent aDropTargetEvent, Object aTarget);

In *MY* view the first parameter, CommonDropAdapter, will *always* be null.   There are other ways to get all of the information you'll most likely need, however, specifically source and destination, and an example of this is shown in the ServersViewDropAdapterAssistant class. 


HOW TO TEST:
   1) Create a server
   2) Create a plain java project with a text file  (file.txt)
   3) Try to drag the java project into the server 
        a) observe failure, dnd does not occur
   4) Try to drag file.txt into the server 
        a) observe failure, dnd does not occur
   5) right-click the text file, select "Make Deployable"
   6) drag file.txt into "Filesets"
       a) observe failure
    7) drag file.txt onto server
       a) observe server deploy and begin to startup   **

At no point should you observe any obscure UI bugs, weird error messages, or a frozen UI. 

** (NOTE: this functionality is how it is in the regular servers view. If you think this is bad functionality then open a new bug for it. Do not use this one) 

> DND support in CNF-based Servers View
> -------------------------------------
>
>                 Key: JBIDE-3608
>                 URL: https://jira.jboss.org/jira/browse/JBIDE-3608
>             Project: Tools (JBoss Tools)
>          Issue Type: Feature Request
>    Affects Versions: 3.0.0.cr1
>            Reporter: Rob Stryker
>             Fix For: 3.0.0.CR2
>
>
> DnD support doesn't exist. Fix it. 

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