Mattias Gaertner wrote:
On Wed, 04 Oct 2006 11:29:51 +0200
Marc Weustink <[EMAIL PROTECTED]> wrote:
Mattias Gaertner wrote:
On Wed, 4 Oct 2006 09:27:03 +0200
"Graeme Geldenhuys" <[EMAIL PROTECTED]> wrote:
Changing a property can change various others as well. For
example changing the Width can change child controls, siblings
and parent.
Yes, but applying this change to the child form should result in
exactly the same consequences, unless the affected components were
changed already... ?
Michael.
Mattias,
This is where my implementation of the Observer using BeginUpdate
and EndUpdate plays a roll. See the tiOPF code I sent you.
Normally the Subject (FormA) would fire off the Notify method for
every small change which could cause lots of screen redraws.
BeginUpdate and EndUpdate allows you to make all those small
changes and then fire off a single Notify call.
BeginUpdate can only be called for the IDE tools (OI, AE, ...). The
component editors will only call the Modified event.
But there is a solution:
We could call the update on Idle.
Not really a nice option and hard to work with if some who knows
future designer plugin needs the result of a modification (I'm just
making things up here).
Then the plugin can force an update.
But...
component editors call Modified. This Modified method can use
Begin/EndModification. If this is passed to the
"derived form" observer, it knows whan all modifications are done
(and can update itself)
Do you mean, all methods, that now call the Modified method should
be changed to call Begin/EndModification?
No,
Modified needs to be modified :)
procedure Modified;
begin
SendBeginModificationToAllBeginEndObeservers;
SendModifiedNotificationToAllModifiedObeservers;
SendEndModificationToAllBeginEndObeservers;
end;
Marc
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