I am using the angular gantt view library. Demo
I don't know why, but i can't start all the tasks collapsed. Basicaly it is just simulate the "Collapse All" button click in Options menu, like $('#btnId').trigger('click'). But not!!
Someone know why?
If I understand your question correctly, you are probably wanting to use the api that is on the gantt's scope. I tested collapsing and expanding the demo you mentioned using the collapseAll and expandAll methods and it worked well. The api also contains methods in its core methods to test when the chart is ready so you can collapse it after the chart is ready.