Is there a standard method for manipulating an element on a touchscreen?

Question

I have a "Gantt-like" task management screen on desktop, where user can choose to extend the duration of a task by dragging on either edges to move either the start date or due date. Or drag at the center of the task to pick up up and move it along the timeline without adjusting the duration.

I now need to translate this onto a tablet. Can the same set of interactions be applied for touchscreen? I'm a bit concern with the following issues:

• fat finger syndrome: The drag actions will be right next to each other, especially if a task is of a very short duration.
• accidentally adjusting task dates when user is scrolling the view. The timeline may extend beyond screen real estate and require both horizontal and vertical scrolling to see all the data.
• drag and drop behaviour is tricky to begin with on a touchscreen

Question: Is there a standard method for this sort of manipulation on a touchscreen? Or am I better off saying no direct interactions on tablets and ask users to use indirect controls with date pickers in a popover?

Answer 1

Either tablet or desktop, this combination has been problematic forever. It's used a lot in video editing software. You have to zoom the timeline in, which in turn, enlarges the task. This enables you to grab the left or right edge and extend.

I like how Apple solves this, although it's a slightly different use case. When you select text, you'll get the two handles on either side of the text. In this case, it's implied that you drag to select. I'd use something similar. Maybe one tap and hold engages the drag and drop and a double tap and engages the handles.