Application programming interfaces for scrolling

An electronic device with a display, a touch-sensitive surface, and software code configured to interact with applications and provide the applications with an application programming interface (API) for performing gesture operations in response to a user input detected on the touch-sensitive surface, detects, via the software code, a drag input that includes movement of a contact on the touch-sensitive surface that corresponds to movement over a displayed scrollable region in an application. While detecting the drag input, the device scrolls on the display, via the software code, the scrollable region of the application in accordance with the drag input. After detecting an end of the drag input, the device continues to scroll on the display, via the software code, the scrollable region in accordance with the drag input including slowing the scroll to a stop over time in accordance with a deceleration factor set using the API.