onDown property Null safety
read / write
A pointer has contacted the screen with a primary button and might begin to move.
The position of the pointer is provided in the callback's details
argument, which is a DragDownDetails object.
See also:
- kPrimaryButton, the button this callback responds to.
- DragDownDetails, which is passed as an argument to this callback.
Implementation
GestureDragDownCallback? onDown;