Scrolling arrays

Question

I need to write a piece of code that loops through an array, selects the
current row in an ArrayField and puts up a dialog box. Something like the
following:
for x in 1 to set.Items do
arrayWidget.CurrentRow=x;
// put up question dialog, if yes do some stuff
end for;
The problem I'm having is with the scrolling of the ArrayField. Lets say my
ArrayField has 5 rows and my data set has 20 rows. When it gets to row 6 the
ArrayWidget generates some (focus) events to scroll the array and bring the 6th
row into view. The problem is these events are not processed until my code is
done and control returns back to the event loop. The user sees the first 5
dialog boxes along with their associated rows, but the remaining 15 dialog
boxes are all displayed while row 5 is highlighted. As soon as my code finishes
the system goes wild doing all the scrolling.
Is there some way of forcing the window to process the pending events (the
opposite of PurgeEvents)? I tried posting my own event to trigger the dialog
but it seemed to get processed before the scroll events. Are there multiple
queues for the window? Do the events have different priorites?
For Express users, you can do the same thing with the
ExpressClassWindow.ScrollToIndex() method. I also tried using
arrayWidget.RequestFocus as the documentation notes that CurrentRow is read
only but they appear to have work the same.
Any help would be appreciated.

Answer 1

The trick is to drive the process from the parent window's event loop
instead of from a FOR loop. That way all of the window events will be
handled promptly. You would need to define one or more custom events to
control this process. I envision the parent window event loop would look
something like this:
when <updateButton>.click do
<arrayWidget>.currentRow = 1;
post self.updateCurrentRow;
when self.updateCurrentRow do
// display dialog to update current row here
post self.updateNext;
when self.updateNext do
if <arrayWidget>.currentRow < set.items then
<arrayWidget>.currentRow = <arrayWidget>.currentRow + 1;
post self.updateCurrentRow;
end if;
Of course there are many variations of this scheme that will achieve the
same result.
Kevin Klein
Millennium Partners, Inc.
Milwaukee, Wisconsin, USA
-----Original Message-----
From: [email protected] <[email protected]>
To: [email protected] <[email protected]>
Date: Thursday, February 12, 1998 3:06 AM
Subject: Scrolling arrays
I need to write a piece of code that loops through an array, selects the
current row in an ArrayField and puts up a dialog box. Something like the
following:
for x in 1 to set.Items do
arrayWidget.CurrentRow=x;
// put up question dialog, if yes do some stuff
end for;
The problem I'm having is with the scrolling of the ArrayField. Lets say my
ArrayField has 5 rows and my data set has 20 rows. When it gets to row 6the
ArrayWidget generates some (focus) events to scroll the array and bring the6th
row into view. The problem is these events are not processed until my codeis
done and control returns back to the event loop. The user sees the first 5
dialog boxes along with their associated rows, but the remaining 15 dialog
boxes are all displayed while row 5 is highlighted. As soon as my codefinishes
the system goes wild doing all the scrolling.
Is there some way of forcing the window to process the pending events (the
opposite of PurgeEvents)? I tried posting my own event to trigger thedialog
but it seemed to get processed before the scroll events. Are there multiple
queues for the window? Do the events have different priorites?
For Express users, you can do the same thing with the
ExpressClassWindow.ScrollToIndex() method. I also tried using
arrayWidget.RequestFocus as the documentation notes that CurrentRow is read
only but they appear to have work the same.
Any help would be appreciated.