Nested Scrollbase

Forum|Forum|1 year ago
May 22, 2025
5 replies
682 views

I am trying put a ScrollWheelWithStyle inside a ScrollContainer.
Currently I can't find a method to pass down dragEvents from the Container to the Wheel.

I tried disabling the scrolling for the Container.
This cause the areas to initiate the draggable to be within the Wheel but the event is still handled by the Container.

I also tried to change the code found in "...\touchgfx\framework\include\touchgfx\containers\ScrollableContainer.hpp", that cause the application to crash in both Simulators.

Does anyone have recommendation on how to have nested Scrollables?

This topic has been closed for replies.

GGODA

Associate II

Hello @Marc_LM ,

I see 2 ways to do that.

Create your elements as custom container
I have tested it.
Create your scrollableContainer and instead of adding your ScrollWheel, create a new custom container that is just your ScrollWheel, then add that custom container to your scrollableContainer
Loop through your children and check if you clicked on one
I have not tested this one, it will take mroe time to implement.
When you start a drag with your finger, TouchGFX will first get a click event of type click, then it we get the drag and finaly when you release your finger it will get a click event of type release.
So you can use the handleClickEvent, check whether it is a click or a release and if it is a click iterate through your children to see if you clicked on one of your children. If you do, change a value to true and set your scrollableContainer to not scrollable, also implement the handleDrageEvent to redirect the drag new X and new Y to your element.
Then, we you get a release, set your scrollableContainer scrollable again.

To see how to implement the second option, you can look at :

the slider custom container to see how to use handleClickEvent and handleDragEvent
this answer 's second code to see how to iterate through the children

I hope this helps you.
If it answers your question, I inivite you to select this post as "best answer".

Regards,

M

Marc_LMAuthor

Senior

Thank you for the suggestion.
I just tried to add a ScrollableContainer as a parent to the slide (example 1).
It too suffers from what I see were the ScrollableContainer starts to drag .
The ScrollableContainer is the culprit that does not propagate the click/drag to its children properly.
I'll take this into advice and remake a new ScrollableContainer.

Side note:
@GaetanGodart, I noticed a bug in the slider. I can just click at the right of it and it will trigger its completion. No sliding required. Not sure I will have time to send you a patched version to explain the bug.

M

Marc_LMAuthor

Senior

I could not change the ScrollableContainer itself but after cloning it and modding it, I nearly got something reasonable where click/drag propagate to children first.

If anyone know how to check if "handle*Event", is processed or not by their children.
I could use that check to enable dragging to children who do not handle them.
Looked into uninitialized vTable entries for object, but all reference discourages as being non-portable.
Any alternative would be welcome.

I am attaching the changed .hpp/.cpp for posterity.

ScrollableContainerModded.hpp

ScrollableContainerModded.cpp