Hi,
    I've been testing the new vertical smooth scrolling, and it seems to work fine (in 15.1.3) . Sometimes it makes an small jump in the opposite direction when you are scrolling pushing the up/down scrollbar button, but is not very important.

 

    The big problem comes with the performance. When you switch to vertical smooth scrolling mode, the performance is heavily decreased. I've been monitoring the control events and realized that the BeforeDrawRaw event is fired multiple times when you only scroll one line (one for every record multiplied for every column). For example, if I'm viewing only the item #1700 (which is taller than the control) with its preview area and I click on the scroll down button, the event is fired about 1700 * 8 columns times (~13,600 times). This causes the performance to decrease, because in every event handle, if you perform a minimal operation (for example, one search in a map, due to the virtual mode) the response time is not acceptable.

 

    I think there are two ways to solve this problem:

 

    1- Is there any way to know if a record is shown? I've tried the "visible" property of the record and the row one but both treat about the visibility not just if they are being shown/drawn. If there'd be any way, I can ignore the calls to BeforeDrawRaw handler.

 

    2- Perhaps you can avoid to fire this event with hidden rows. In my opinion, it has no sense to fire a BeforeDrawRaw event when you are not going to draw the row, hasn't it?

 

    Any recomendation?

 

    Kind regards,

 

F.José Sen

 

    Exactly. Perhaps you could fire only the MeasureRow and the MeasurePreviewItem events if you just need to calculate the heights of the rows.

 

    Meanwhile, is there any way to know (inside the BeforeDrawRow event handler) if the row is going to be drawn or if it is called just to perform the measurement of the row? I've been playing with "TopRowIndex" control property but it always returns 0 (inside BeforeDrawRow handler). This could help to determine if the row will be drawn or not (to avoid data searches, etc.).

 

 

    Can you say me anything about this? It would be enought for me now just to know if the row is going to be really drawn during the BeforeDrawRow event handler or not (just called to meaure it).

 

    Kind regards,

 

F.José Sen

 

    Also, I would like to know if someone from Codejock Support Team will answer to this topic any time.

 

    Kind regards,

 

F.José Sen

    Why not just fire the MeasureRow and the MeasurePreviewItem events if you only need to measure the rows? I cannot understand why you need to fire the BeforeDrawRaw event to measure the height of the rows if the user won't return any information about that (the height of the row).

 

    On the other hand, if you need to fire it also for measuring the rows, could you include any parameter (or another resource, like a property we can read) to inform us that the event is being fired just for measuring purposes? Think that this event (BeforeDrawRow) is often used to perform some heavy operations (searching data to draw text, etc.) that we can ignore if we could know that the row won't really be drawn after the event. This is the main reason, at least for me, why the performance is bad :-)

 

    Kind regards,

 

F.José Sen