Disable change hour when dragging from day to day

when drag item 3.1 to date 01 => date 02 i want

but not

picture first

Hi @linhtv97
If I understand you correctly, you want to drag tasks from day-to-day without changing their hours-minutes settings, am i right?
In order to do this, you should change some config settings and add additional drag logic to the onBeforeTaskChanged event(for example).
In config, you need to disable round_dnd_dates to forbid rounding dates after drag. And set duration_unit to hours in order to avoid collapsing for tasks that are less than one-day duration.
In the onBeforeTaskChanged you should store start/end hours and minutes of the unmodified tasks and apply them to the modified ones.
Here is a workable example of how it could be implemented:
http://snippet.dhtmlx.com/3333bf4b4
API:
duration_unit
https://docs.dhtmlx.com/gantt/api__gantt_duration_unit_config.html
round_dnd_dates
https://docs.dhtmlx.com/gantt/api__gantt_round_dnd_dates_config.html
onBeforeTaskChanged
https://docs.dhtmlx.com/gantt/api__gantt_onbeforetaskchanged_event.html

If it is not the thing you need, could you please clarify your question?

btw, is it the same question:
Disable autosize when drag task ?

oki thanks, I did it