Method for scroll bar control on a touchpad

1. A control process implemented in a touchpad to perform scroll bar control thereby, the process comprising:

detecting if a number of fingers touching on the touchpad is equal to or larger than a first threshold, for directly starting up a scroll bar control function which remains in operation independent of the movement of the fingers on the touchpad, until all fingers are removed from the touchpad;

selectively switching between alternative cursor control and scroll bar control functions for the touchpad responsive to the detection independent of a sliding movement of said number of fingers;

in the scroll bar control function, detecting the sliding movement of one or more fingers on the touchpad for scrolling on a window in accordance with the finger movement;

simultaneously evaluating a vertical distance and a horizontal distance of the movement of the finger or fingers for scrolling a vertical scroll bar and a horizontal scroll bar on the window responsive to displacement of the finger or fingers on the touchpad, respectively; and

continuing said scroll bar control function when at least one finger remains on said touchpad and said number of fingers remaining on said touchpad is larger than a second threshold;

wherein said first threshold is larger than one and said second threshold.

2. The control process implemented as recited in claim 1 , wherein the first threshold is two.

3. The control process implemented as recited in claim 1 , wherein the process further comprises terminating the scroll bar control function once said number of fingers touching on the touchpad are equal to or less than said second threshold.

4. The control process implemented as recited in claim 3 , wherein the second threshold is zero.

5. A control process implemented in a touchpad to perform scroll bar control thereby, the process comprising:

detecting if a number of fingers touching on the touchpad is equal to or larger than a first threshold, for directly starting up a scroll bar control function which remains in operation until all fingers are removed from the touchpad;

selectively switching between alternative cursor control and scroll bar control functions for the touchpad responsive to the detection independent of a sliding movement of said number of fingers;

in the scroll bar control function, detecting the sliding movement of one or more fingers on the touchpad for scrolling on a window in accordance with the finger movement;

evaluating a vertical distance and a horizontal distance of the movement for scrolling a vertical scroll bar on the window if the vertical distance is larger than the horizontal distance over a reference, or scrolling a horizontal scroll bar on the window if the horizontal distance is larger than the vertical distance over the reference; and

continuing said scroll bar control function when at least one finger remains on said touchpad and said number of fingers remaining on said touchpad is larger than a second threshold;

wherein said first threshold is larger than one and said second threshold.

6. The control process implemented as recited in claim 5 , wherein the process further comprises determining a scrolling amount for the vertical scroll bar in proportion to a difference between the vertical distance and the horizontal distance.

7. The control process implemented as recited in claim 5 , wherein the process further comprises determining a scrolling amount for the vertical scroll bar in proportion to the vertical distance.

8. The control process implemented as recited in claim 5 , wherein the process further comprises determining a scrolling amount for the horizontal scroll bar in proportion to a difference between the horizontal distance and the vertical distance.

9. The control process implemented as recited in claim 5 , wherein the process further comprises determining a scrolling amount for the horizontal scroll bar in proportion to the horizontal distance.

10. A control process implemented in a touchpad to perform a process for scrolling window thereby, the process comprising:

detecting a number of fingers touching on the touchpad for directly starting up a scrolling window function which remains in operation until all fingers are removed from the touchpad if the number of fingers is equal to or larger than a first threshold independent of a sliding movement of said number of fingers;

in the scrolling window function, evaluating a vertical distance of a movement of one or more fingers sliding on the touchpad; and

transmitting a vertical scrolling amount to a host system according to the vertical distance for scrolling a window in a vertical direction;

wherein said first threshold is at least one.

11. The control process implemented as recited in claim 10 , wherein the first threshold is two.

12. The control process implemented as recited in claim 10 , wherein the process further comprises continuing the scrolling window function during said number of fingers touching on the touchpad are not less than a second threshold;

wherein the second threshold is one.

13. The control process implemented as recited in claim 10 , wherein the process further comprises terminating the scrolling window function once said number of fingers touching on the touchpad are equal to or less than a second threshold;

wherein the second threshold is zero.

14. The control process implemented as recited in claim 10 , wherein the process further comprises the steps of:

evaluating a horizontal distance of the movement; and

transmitting a horizontal scrolling amount to the host system according to the horizontal distance for scrolling the window in a horizontal direction.

15. The control process implemented as recited in claim 14 , wherein the horizontal scrolling amount for scrolling the window in the horizontal direction is proportional to the horizontal distance.

16. The control process implemented as recited in claim 10 , wherein the vertical scrolling amount for scrolling the window in the vertical direction is proportional to the vertical distance.