Q: Form SELECT support: what to do in the DW code?
I'm working on supporting SELECT controls in forms. I've got a working first draft of the changes to the Dillo parser, but it's of no use yet because the Dillo menu widgets are incomplete; the menus report every item as selected and the items don't yet do anything when you select them (unless I've missed something). So I'm wondering how to fix this. We need a way to connect Items to callbacks. We need some abstraction because ListResources and OptionMenuResources will do things differently. The most straightforward thing to do is add a virtual function to SelectionResource that returns the callback to attach to the FLTK items we create. Is that OK, or do we need something more abstract? Assuming the Item will be passed to the callback, we really need a way to get back from the Item to the ListResource. The easiest way is to simply add a new data member to Itens that points to the ListResource. Again, is that OK, or should we be more abstract and not hardwire that implentation into the base class? I'm a fan of abstraction (I used to be a mathematician) but I'm inclined not to go too abstract unless there's good reason, so I think the suggestions above are good enough. Thoughts? If we do the above then fixing OptionMenuResource should be easy; add a data member to record the last selected Item, connect Items to a callback that updates that data member and implement isSelected() to compare the item being queried with the selected item. Is it worth submitting a patch along these lines, or should I do it differently? Regards, Jeremy Henty
On Tue, Dec 25, 2007 at 07:20:43PM +0000, Jeremy Henty wrote:
I'm working on supporting SELECT controls in forms. I've got a working first draft of the changes to the Dillo parser, but it's of no use yet because the Dillo menu widgets are incomplete; the menus report every item as selected and the items don't yet do anything when you select them (unless I've missed something). So I'm wondering how to fix this.
We need a way to connect Items to callbacks. We need some abstraction because ListResources and OptionMenuResources will do things differently. The most straightforward thing to do is add a virtual function to SelectionResource that returns the callback to attach to the FLTK items we create. Is that OK, or do we need something more abstract?
Sounds ok to me, if it is necessary. I'm only starting to understand the FltkSelectionResource stuff however :-) Or would it be possible to connect the callback in createNewMenu() which is virtual already? If you look at the test/menu.cxx from fltk-2, there they install one callback per menu and get the item using get_item(). Regards, Johannes
Assuming the Item will be passed to the callback, we really need a way to get back from the Item to the ListResource. The easiest way is to simply add a new data member to Itens that points to the ListResource. Again, is that OK, or should we be more abstract and not hardwire that implentation into the base class?
I'm a fan of abstraction (I used to be a mathematician) but I'm inclined not to go too abstract unless there's good reason, so I think the suggestions above are good enough. Thoughts?
If we do the above then fixing OptionMenuResource should be easy; add a data member to record the last selected Item, connect Items to a callback that updates that data member and implement isSelected() to compare the item being queried with the selected item.
Is it worth submitting a patch along these lines, or should I do it differently?
Regards,
Jeremy Henty
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The most straightforward thing to do is add a virtual function to SelectionResource that returns the callback to attach to the FLTK items we create. Is that OK, or do we need something more abstract?
Sounds ok to me, if it is necessary. I'm only starting to understand the FltkSelectionResource stuff however :-)
I've got something working that adds the callback as a virtual function in the FltkListResource::Item class. Unfortunately it requires adding some other virtual functions and some extremely verbose template code (+ use of the typename keyword to get it all through the parser) so I'm keen to simplify things.
Or would it be possible to connect the callback in createNewMenu() which is virtual already? If you look at the test/menu.cxx from fltk-2, there they install one callback per menu and get the item using get_item().
That might be much simpler than what I currently have. I'd much rather reuse the virtual functions we already have than add new ones. Thanks for the tip, I'll give it a go! Jeremy Henty
participants (2)
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Johannes.Hofmann＠gmx.de -
onepoint＠starurchin.org