nsIClipboardDragDropHooks
Interfaces for overriding the built-in drag, drop, copy, and paste
implementations in the content area and editors. Use this to do things
such as prevent a drag from starting, adding or removing
data and flavors, or preventing the drop.
Embedders who want to have these hooks made available should implement
nsIClipboardDragDropHooks and use the command manager to send the
appropriate commands with these parameters/settings:
command: cmd_clipboardDragDropHook
params value type possible values
"addhook" isupports nsIClipboardDragDropHooks as nsISupports
"removehook" isupports nsIClipboardDragDropHooks as nsISupports
Notes:
* Overrides/hooks need to be added to each window (as appropriate).
Adding them to the first window does not enable them for every window.
* If more than one implementation is set for a window, the hooks will be
called in the order they are added.
* Adding the same hook to the same window will not add a second call.
Each hook can only be called once per user action/api.
* Not all hooks are guaranteed to be called. If there are multiple hooks
set for a window, any of them has an opportunity to cancel the action
so no further processing will occur.
* If any errors occur (without setting the boolean result) the default
action will occur.
* AllowDrop will be called MANY times during drag so ensure that it is
efficient.
Methods
allowStartDrag(event)
Prevents the drag from starting
Parameters
| event |
DOM event (drag gesture)
|
Returns
| FALSE drag is cancelled, does not go to OS
|
allowDrop(event, session)
Tells gecko whether a drop is allowed on this content area
Parameters
| event |
DOM event (drag over)
|
| session |
the drag session from which client can get
the flavors present or the actual data
|
Returns
| FALSE indicates to OS drop is not allowed. On win32, this
will change the cursor to "reject".
|
onCopyOrDrag(aEvent, trans)
Alter the flavors or data presented to the OS
Used for drag and copy actions
Because this can be called many times, it is highly recommended
that the implementation be very efficient so user feedback is
not negatively impacted.
Parameters
| event |
DOM event (drag drop); null if triggered by copy.
|
| trans |
the transferable holding the list of flavors
and the data for each flavor
|
Returns
| FALSE copy/drag is cancelled, does not go to OS
|
onPasteOrDrop(event, trans)
Provide an alternative action to the built-in behavior when
something is dropped on the browser or in an editor
Parameters
| event |
DOM event (drag drop); null if triggered by paste.
|
| trans |
the transferable holding the list of flavors
and the data for each flavor
|
Returns
| FALSE action was not overridden, do built-in behavior
|