TALVertscrollbox - Changing the Viewport (Moving list up and down) does not trigger OnViewportPositionaChange

[ETSPMeder]

Hi,

I was trying to implement some sort of "pull to refresh" by using the TALVerstScrollBox and using the OnViewportPositionChange event for that. But for me it looks like the ViewportChange event is not getting triggert by any movement of the List.

[Zeus64]

If you look TALDynamicListBox their is a pull to refresh implementation that you can get inspired from. normally ViewportChange must be triggered else their is a problem. i will check it

[ETSPMeder]

I had a look into the TALDynamicListBox. Is there any documentation on how to use it? I can see the JSON that is loaded into the component, but using that list view for an internal database feels somewhat counterintuitive.

Anyway, the ViewPortChanged event is not triggered when scrolling the VertBox. Did you have a chance to check this? I will need that event for other stuff as well, like saving the actual Position before Updating the view to get back to that point.

[ETSPMeder]

I check with a new Blank form and only VertScrollBox on it. The Event gets triggert. On my investigation on that I found another thing, maybe the behavior in the Scrollbox depands on that one.

Here is a Sample Project. This Combination of Pagecontrol, VertScrollBox, Rect and Text give a Range Error from inside the Alcinoe.FMX.BreakText.pas -> _BreakText. When used on Windows.

ALVertScrollPageControl.zip

[ETSPMeder]

Sorry, I found my bug in the Implementation. I Copyed your logik from the Demo, to automaticaly move ScrollBox, into my template Form. So the ScrollBoxViewportPositionChange gets overwritten everytime my Form is created.
Please completly forget what I said on this Topic. I should drink some more coffee today, maybe it helps 😂

The initial Problem is solved. The Range Error is still there.