Auto enable Cut, Copy, Paste menu items
ambassador at fourthworld.com
Thu Sep 14 20:03:57 EDT 2006
Bill Vlahos wrote:
> Oh now that is the most ridiculously, wonderfully, and embarrassingly
> easy thing to do.
> Here it is:
> on mouseDown -- Put in button "Edit" of menubar group of stack
> -- This example assumes text in fields not other clipboard types
> if the selectedText is empty then -- nothing selected
> disable menuItem 1 of me -- Cut
> disable menuItem 2 of me -- Copy
> else -- text is selected
> enable menuItem 1 of me -- Cut
> enable menuItem 2 of me -- Copy
> end if
> if the clipboard is "text" then -- Is there text in the clipboard?
> enable menuItem 3 of me -- Paste
> else -- Either no text in clipboard or data type of clipboard is not
> disable menuItem 3 of me -- Paste
> end if
> end mouseDown
There are two issues with the above:
1. On a Mac the individual menu buttons do not receive a mouseDown
message when they're in the current menu bar. But the menuGroup object
does get a mouseDown, so just put the handler there (modified of course
for the object change).
2. The strategy of updating menu items when they become visible to the
user (mouseDown) is how many frameworks, like the ol' Think Class
Library, work. But in Rev this is problematic once we consider keyboard
For example, if you disable the Paste item when the user mouses down on
the Edit menu and the clipboard is empty, and then later the user has
something on the clipboard and attempts to use Cmd-V to paste it, the
command key won't trigger the menu item because it's still disabled.
So while I used to use the update-prior-to-display method, these days I
tend to use an update-when-the-triggering-action-first-happens method.
In the same example above, I would modify the contents of the Edit menu
based on global handlers in a frontScript that monitor selectionChanged
and related actions, and in any handlers that can affect menu updates
such as enabling Paste after a Cut or Copy is performed, etc.
It might make things simpler if Rev had a way to interpret keyboard
shortcuts, recognize that they're part of the current menu set, and
trigger a mouseDown event in response so you could take the simple path
of using the update-prior-to-display method. Anyone know if such a
feature request has been submitted to Bugzilla? I couldn't find one....
Managing Editor, revJournal
Rev tips, tutorials and more: http://www.revJournal.com
More information about the Use-livecode