Hi Jake,
(this is a cross post from gmane.comp.lib.litwindow.user that hopefully
is also of interest to the current GUI discussion on the boost list. The
question was how to write a generic implementation for the
add/modify/delete user interface pattern)
Jake Skinner wrote:
> I am having some difficulty getting my head around the RULE syntax and
> what can be achieved. I am trying to implement the add/modify/delete
> pattern which appears to have been catered for.
>
you are a bit ahead of the litwindow schedule here.
I've put up a new article on the website (a correction of the few layout
problems will appear later this day)
http://www.litwindow.com/Library/Articles/rapidui_article_3.htm
Here is what works:
You can already handle the 'modify' part of the add/modify/delete
pattern. Have a look at the RSS Reader tutorial, Step 3 and 4 in the
documentation.
Here is what does not yet work:
Action rules have yet to be defined. So you cannot fire an action using
the rules and that is the reason why the add/modify/delete rule has to
be written yet.
To implement Add you will have to intercept the event yourself.
What you can do is write a generic algorithm to add a new element and
show it. Here is the rough outline:
void AddElement(RapidUI &r, string listBoxName)
{
// first get the aggregate object for the list box
aggregate listbox=r.GetWindowAccessor(listBoxName).get_aggregate();
// next get a container object for the "Items" property
// of the list box
container items=listbox["Items"];
if (items.is_valid()==false) {
lw_log() << "Cannot add! List box is not attached to a container.";
return;
}
// now get an accessor to the currently selected element
accessor element=listbox["Current"];
// this accessor will contain valid *type* information
// even if no *current* element is selected
// the next line will create a new object on the heap with 'new'
// the new object will have the same type as 'Current'
accessor newObject=create_object(element.get_type());
// insert it (copying it) at the first position into the container
items.insert(items.begin(), newObject);
// delete the temporary object since a copy of it is now contained
// in the container
newObject.destroy();
// finally tell RapidUI to update the UI
// this will update the list box and the new element will
// be shown at position 1
r.ValueChanged(items.get_accessor(), false, false);
}
This is a generic function, meaning that it will work
- with any kind of container
- with any type of elements contained in the container
- with any list widget that knows "Items" and "Current"
provided the appropriate data adapters have been created.
Hope this helps and thank you for your interest.
BTW, I am cc-ing this to the boost mailing list
Regards
Hajo
Speed up GUI coding by a factor of 10x
http://www.litwindow.com/library
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