Continuous scrolling list with acceleration

1. A method, comprising:

at a portable electronic device with a touch-sensitive display:

determining a movement of a point of contact by a user on the touch-sensitive display;

scrolling through a list of items on the touch-sensitive display in response to the movement; and

accelerating the scrolling in response to an accelerated movement of the point of contact,

wherein determining the movement of the point of contact includes determining the accelerated movement of the point of contact over a predefined number of time intervals and, when data for movement of the point of contact is missing for a respective time interval,

the accelerated movement of the point of contact in the respective time interval is determined by projecting accelerated movement of the point of contact in a time interval preceding the respective time interval.

2. The method of claim 1 , wherein the scrolling and accelerating are in accordance with a simulation of a physical device having friction.

3. The method of claim 1 , wherein the accelerated movement of the point of contact comprises a first sweeping motion of the point of contact along a predefined axis of the touch-sensitive display;

the method further comprising:

further accelerating the scrolling in response to a second sweeping motion of the point of contact along the predefined axis of the touch-sensitive display.

4. The method of claim 1 , wherein the accelerated movement of the point of contact comprises a first user gesture oriented along a predefined axis of the touch-sensitive display;

the method further comprising:

further accelerating the scrolling in response to a second user gesture oriented along the predefined axis of the touch-sensitive display.

5. The method of claim 1 , further comprising reversing a direction of scrolling in response to the scrolling intersecting a virtual boundary corresponding to a terminus of the list.

6. The method of claim 5 , wherein the reversing corresponds to a damped motion.

7. The method of claim 1 , wherein the accelerated movement of the point of contact includes an accelerated movement of the point of contact followed by a breaking of the point of contact.

8. The method of claim 1 , further comprising stopping the scrolling in accordance with the user breaking the point of contact and then establishing a substantially stationary point of contact with the touch-sensitive display for at least a pre-determined period of time.

9. The method of claim 1 , further comprising displaying respective index symbols adjacent corresponding subsets of the list of items while scrolling the list of items.

10. The method of claim 1 , further comprising:

displaying a set of index symbols in a first region of the touch-sensitive display while displaying the scrolling list of items in a second region of the touch-sensitive display; and

upon detecting that the point of contact is in the first region of the touch-sensitive display and corresponds to a respective index symbol of the set of index symbols, scrolling the list of items to a corresponding subset of the list of items.

11. The method of claim 1 , further comprising:

determining if the movement of the point of contact corresponds to a displacement greater than a pre-determined magnitude, wherein the scrolling occurs when the movement corresponds to the displacement greater than the pre-determined magnitude.

12. The method of claim 11 , further comprising:

including an offset in the point of contact when scrolling through the list of items, wherein the offset corresponds to the pre-determined magnitude of the displacement, and wherein the offset allows the scrolling to commence smoothly.

13. A portable electronic device, comprising:

a touch-sensitive display;

one or more processors;

a memory; and

one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including:

instructions for determining a movement of a point of contact by a user on the touch-sensitive display;

instructions for scrolling through a list of items on the touch-sensitive display in response to the movement; and

instructions for accelerating the scrolling in response to an accelerated movement of the point of contact,

wherein determining the movement of the point of contact includes determining the accelerated movement of the point of contact over a predefined number of time intervals and, when data for movement of the point of contact is missing for a respective time interval,

the accelerated movement of the point of contact in the respective time interval is determined by projecting accelerated movement of the point of contact in a time interval preceding the respective time interval.

14. A portable electronic device, comprising:

touch-sensitive display means;

processor means;

memory means; and

one or more programs mechanisms, wherein the one or more program mechanisms are stored in the memory means and configured to be executed by the processor means, the one or more program mechanisms including:

instructions for determining a movement of a point of contact by a user on the touch-sensitive means;

instructions for scrolling through a list of items on the touch-sensitive means in response to the movement; and

instructions for accelerating the scrolling in response to an accelerated movement of the point of contact,

wherein determining the movement of the point of contact includes determining the accelerated movement of the point of contact over a predefined number of time intervals and, when data for movement of the point of contact is missing for a respective time interval,

the accelerated movement of the point of contact in the respective time interval is determined by projecting accelerated movement of the point of contact in a time interval preceding the respective time interval.

15. A graphical user interface on a portable electronic device with a touch-sensitive display, a memory, and one or more processors to execute one or more programs stored in the memory, the graphical user interface comprising:

a list of items on the touch sensitive display that scrolls in response to determining a movement of a point of contact by a user on the display,

wherein determining the movement of the point of contact includes determining the accelerated movement of the point of contact over a predefined number of time intervals and, when data for movement of the point of contact is missing for a respective time interval,

the accelerated movement of the point of contact in the respective time interval is determined by projecting accelerated movement of the point of contact in a time interval preceding the respective time interval.

16. A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a portable electronic device with a touch-sensitive display, cause the portable electronic device to perform a method comprising:

determining a movement of a point of contact by a user on the touch-sensitive display;

scrolling through a list of items on the touch-sensitive display in response to the movement; and

accelerating the scrolling in response to an accelerated movement of the point of contact,

wherein determining the movement of the point of contact includes determining the accelerated movement of the point of contact over a predefined number of time intervals and, when data for movement of the point of contact is missing for a respective time interval, the accelerated movement of the point of contact in the respective time interval is determined by projecting accelerated movement of the point of contact in a time interval preceding the respective time interval.