[DUG] ListView - Scroll Event

[Eric A]

Yes, could do that, with the understanding that it will result in some 
extra overhead due to fetching two lots of child records if I don't 
detect which is the last non-nil item notified.  That's what I meant by 
"messy".

From: robo555 at gmail.com
Date: Sun, 27 Jul 2014 20:57:40 +0200
To: delphi at listserver.123.net.nz
Subject: Re: [DUG] ListView - Scroll Event

So you just need to use the OnChange event, and check the item is not nil. From memory I don't think you need to check whether item is different to previous item.

Robo




On Sun, Jul 27, 2014 at 8:52 PM, Eric A <eaa603 at hotmail.com> wrote:





Yes, multiple OnChange events are generated on the ListView control, for
 both mouse clicks and navigation key depressions, as follows:

a) First mouse click or down arrow/PgDn key depression:
- Item = new selection

b) subsequent mouse clicks or down arrow/PgDn key depressions:


- Item - current selection
- Item= nil
- Item = new selection

Seems messy ...

From: robo555 at gmail.com
Date: Sun, 27 Jul 2014 12:28:33 +0200


To: delphi at listserver.123.net.nz
Subject: Re: [DUG] ListView - Scroll Event

>From memory, when a record changes, first an event gets fired where selected item is nil, then a second event gets fire where selected item is the new item.






On Sun, Jul 27, 2014 at 11:07 AM, Eric A <eaa603 at hotmail.com> wrote:







(Delphi 7)

I  wish to detect the user selecting a row (item) in a ListView component to display child records for  the item in another control.  

There is no "OnScroll" event for this control.  I can use the "OnClick" event OK for a selection cia the mouse, but how do I detect when a user scrolls on to a record by using the arrow keys (or PgUp, PgDn or moving the scrollbar ?





I have tried the using the OnChange event but it seems that there are two events generated for each movement by the arrow keys.

Does anyone have a code snippet to accomplish this?





Eric.
 		 	   		  

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